Added: incubator/nifi/site/trunk/docs/nifi-docs/html/expression-language-guide.html URL: http://svn.apache.org/viewvc/incubator/nifi/site/trunk/docs/nifi-docs/html/expression-language-guide.html?rev=1682431&view=auto ============================================================================== --- incubator/nifi/site/trunk/docs/nifi-docs/html/expression-language-guide.html (added) +++ incubator/nifi/site/trunk/docs/nifi-docs/html/expression-language-guide.html Fri May 29 11:51:20 2015 @@ -0,0 +1,3039 @@ +<!-- + Licensed to the Apache Software Foundation (ASF) under one or more + contributor license agreements. See the NOTICE file distributed with + this work for additional information regarding copyright ownership. + The ASF licenses this file to You under the Apache License, Version 2.0 + (the "License"); you may not use this file except in compliance with + the License. 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#ddddd8!important;padding-bottom:0!important} +.sect1{padding-bottom:0!important} +.sect1+.sect1{border:0!important} +#header>h1:first-child{margin-top:1.25rem} +body.book #header{text-align:center} +body.book #header>h1:first-child{border:0!important;margin:2.5em 0 1em 0} +body.book #header .details{border:0!important;display:block;padding:0!important} +body.book #header .details span:first-child{margin-left:0!important} +body.book #header .details br{display:block} +body.book #header .details br+span:before{content:none!important} +body.book #toc{border:0!important;text-align:left!important;padding:0!important;margin:0!important} +body.book #toc,body.book #preamble,body.book h1.sect0,body.book .sect1>h2{page-break-before:always} +.listingblock code[data-lang]:before{display:block} +#footer{background:none!important;padding:0 .9375em} +#footer-text{color:rgba(0,0,0,.6)!important;font-size:.9em} +.hide-on-print{display:none!important} +.print-only{display:block!important} +.hide-for-print{display:none!important} +.show-for-print{display:inherit!important}} +</style> +<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.2.0/css/font-awesome.min.css";> +</head> +<body class="article"> +<div id="header"> +<h1>Apache NiFi Expression Language Guide</h1> +<div class="details"> +<span id="author" class="author">Apache NiFi Team</span><br> +<span id="email" class="email"><a href="mailto:[email protected]";>[email protected]</a></span><br> +</div> +<div id="toc" class="toc"> +<div id="toctitle">Table of Contents</div> +<ul class="sectlevel1"> +<li><a href="expression-language-guide.html#overview">Overview</a></li> +<li><a href="expression-language-guide.html#structure">Structure of a NiFi Expression</a></li> +<li><a href="expression-language-guide.html#usage">Expression Language in the Application</a> +<ul class="sectlevel2"> +<li><a href="expression-language-guide.html#editor">Expression Language Editor</a></li> +</ul> +</li> +<li><a href="expression-language-guide.html#functions">Functions</a> +<ul class="sectlevel2"> +<li><a href="expression-language-guide.html#types">Data Types</a></li> +</ul> +</li> +<li><a href="expression-language-guide.html#boolean">Boolean Logic</a> +<ul class="sectlevel2"> +<li><a href="expression-language-guide.html#isnull">isNull</a></li> +<li><a href="expression-language-guide.html#notnull">notNull</a></li> +<li><a href="expression-language-guide.html#isempty">isEmpty</a></li> +<li><a href="expression-language-guide.html#equals">equals</a></li> +<li><a href="expression-language-guide.html#equalsignorecase">equalsIgnoreCase</a></li> +<li><a href="expression-language-guide.html#gt">gt</a></li> +<li><a href="expression-language-guide.html#ge">ge</a></li> +<li><a href="expression-language-guide.html#lt">lt</a></li> +<li><a href="expression-language-guide.html#le">le</a></li> +<li><a href="expression-language-guide.html#and">and</a></li> +<li><a href="expression-language-guide.html#or">or</a></li> +<li><a href="expression-language-guide.html#not">not</a></li> +</ul> +</li> +<li><a href="expression-language-guide.html#strings">String Manipulation</a> +<ul class="sectlevel2"> +<li><a href="expression-language-guide.html#toupper">toUpper</a></li> +<li><a href="expression-language-guide.html#tolower">toLower</a></li> +<li><a href="expression-language-guide.html#trim">trim</a></li> +<li><a href="expression-language-guide.html#urlencode">urlEncode</a></li> +<li><a href="expression-language-guide.html#urldecode">urlDecode</a></li> +<li><a href="expression-language-guide.html#substring">substring</a></li> +<li><a href="expression-language-guide.html#substringbefore">substringBefore</a></li> +<li><a href="expression-language-guide.html#substringbeforelast">substringBeforeLast</a></li> +<li><a href="expression-language-guide.html#substringafter">substringAfter</a></li> +<li><a href="expression-language-guide.html#substringafterlast">substringAfterLast</a></li> +<li><a href="expression-language-guide.html#append">append</a></li> +<li><a href="expression-language-guide.html#prepend">prepend</a></li> +<li><a href="expression-language-guide.html#replace">replace</a></li> +<li><a href="expression-language-guide.html#replaceall">replaceAll</a></li> +<li><a href="expression-language-guide.html#replacenull">replaceNull</a></li> +<li><a href="expression-language-guide.html#replaceempty">replaceEmpty</a></li> +<li><a href="expression-language-guide.html#length">length</a></li> +</ul> +</li> +<li><a href="expression-language-guide.html#searching">Searching</a> +<ul class="sectlevel2"> +<li><a href="expression-language-guide.html#startswith">startsWith</a></li> +<li><a href="expression-language-guide.html#endswith">endsWith</a></li> +<li><a href="expression-language-guide.html#contains">contains</a></li> +<li><a href="expression-language-guide.html#find">find</a></li> +<li><a href="expression-language-guide.html#matches">matches</a></li> +<li><a href="expression-language-guide.html#indexof">indexOf</a></li> +<li><a href="expression-language-guide.html#lastindexof">lastIndexOf</a></li> +</ul> +</li> +<li><a href="expression-language-guide.html#numbers">Mathematical Operations and Numeric Manipulation</a> +<ul class="sectlevel2"> +<li><a href="expression-language-guide.html#plus">plus</a></li> +<li><a href="expression-language-guide.html#minus">minus</a></li> +<li><a href="expression-language-guide.html#multiply">multiply</a></li> +<li><a href="expression-language-guide.html#divide">divide</a></li> +<li><a href="expression-language-guide.html#mod">mod</a></li> +<li><a href="expression-language-guide.html#toradix">toRadix</a></li> +</ul> +</li> +<li><a href="expression-language-guide.html#dates">Date Manipulation</a> +<ul class="sectlevel2"> +<li><a href="expression-language-guide.html#format">format</a></li> +<li><a href="expression-language-guide.html#todate">toDate</a></li> +<li><a href="expression-language-guide.html#now">now</a></li> +</ul> +</li> +<li><a href="expression-language-guide.html#type_cast">Type Coercion</a> +<ul class="sectlevel2"> +<li><a href="expression-language-guide.html#tostring">toString</a></li> +<li><a href="expression-language-guide.html#tonumber">toNumber</a></li> +</ul> +</li> +<li><a href="expression-language-guide.html#subjectless">Subjectless Functions</a> +<ul class="sectlevel2"> +<li><a href="expression-language-guide.html#ip">ip</a></li> +<li><a href="expression-language-guide.html#hostname">hostname</a></li> +<li><a href="expression-language-guide.html#uuid">UUID</a></li> +<li><a href="expression-language-guide.html#nextint">nextInt</a></li> +</ul> +</li> +<li><a href="expression-language-guide.html#multi">Evaluating Multiple Attributes</a> +<ul class="sectlevel2"> +<li><a href="expression-language-guide.html#anyattribute">anyAttribute</a></li> +<li><a href="expression-language-guide.html#allattributes">allAttributes</a></li> +<li><a href="expression-language-guide.html#anymatchingattribute">anyMatchingAttribute</a></li> +<li><a href="expression-language-guide.html#allmatchingattributes">allMatchingAttributes</a></li> +<li><a href="expression-language-guide.html#anydelineatedvalue">anyDelineatedValue</a></li> +<li><a href="expression-language-guide.html#alldelineatedvalues">allDelineatedValues</a></li> +<li><a href="expression-language-guide.html#join">join</a></li> +<li><a href="expression-language-guide.html#count">count</a></li> +</ul> +</li> +</ul> +</div> +</div> +<div id="content"> +<div class="sect1"> +<h2 id="overview"><a class="anchor" href="expression-language-guide.html#overview"></a>Overview</h2> +<div class="sectionbody"> +<div class="paragraph"> +<p>All data in Apache NiFi is represented by an abstraction called a FlowFile. +A FlowFile is comprised of two major pieces: content and attributes. +The content portion of the FlowFile represents the data on which to operate. +For instance, if a file is picked up from a local file system using the +GetFile Processor, the contents of the file will become the contents of the +FlowFile.</p> +</div> +<div class="paragraph"> +<p>The attributes portion of the FlowFile represents information about the data +itself, or metadata. Attributes are key-value pairs that represent what is +known about the data as well as information that is useful for routing and +processing the data appropriately. +Keeping with the example of a file that is picked up from +a local file system, the FlowFile would have an attribute called <code>filename</code> that +reflected the name of the file on the file system. Additionally, the FlowFile will +have a <code>path</code> attribute that reflects the directory on the file system that this +file lived in. The FlowFile will also have an attribute named <code>uuid</code>, which is a +unique identifier for this FlowFile.</p> +</div> +<div class="paragraph"> +<p>However, placing these attributes on a FlowFile do not provide much benefit +if the user is unable to make use of them. The NiFi Expression Language provides +the ability to reference these attributes, compare them to other values, +and manipulate their values.</p> +</div> +</div> +</div> +<div class="sect1"> +<h2 id="structure"><a class="anchor" href="expression-language-guide.html#structure"></a>Structure of a NiFi Expression</h2> +<div class="sectionbody"> +<div class="paragraph"> +<p>The NiFi Expression Language always begins with the start delimiter <code>${</code> and ends +with the end delimiter <code>}</code>. Between the start and end delimiters is the text of the +Expression itself. In its most basic form, the Expression can consist of just an +attribute name. For example, <code>${filename}</code> will return the value of the “filename” +attribute.</p> +</div> +<div class="paragraph"> +<p>In a slightly more complex example, we can instead return a manipulation of this value. +We can, for example, return an all upper-case version of the filename by calling the +<code>toUpper</code> function: <code>${filename:toUpper()}</code>. In this case, we reference the “filename” +attribute and then manipulate this value by using the <code>toUpper</code> function. A function call +consists of 5 elements. First, there is a function call delimiter <code>:</code>. Second is the name +of the function - in this case, “toUpper”. Next is an open parenthesis (<code>(</code>), followed +by the function arguments. The arguments necessary are dependent upon which function +is being called. In this example, we are using the <code>toUpper</code> function, which does not +have any arguments, so this element is omitted. Finally, the closing parenthesis (<code>)</code>) +indicates the end of the function call. There are many different functions that are supported +by the Expression Language to achieve many different goals. Some functions provide String (text) +manipulation, such as the <code>toUpper</code> function. Others, such as the <code>equals</code> and <code>matches</code> functions, +provide comparison functionality. Functions also exist for manipulating dates and times and +for performing mathematical operations. Each of these functions is described below, in the +<<functions> section, with an explanation of what the function does, the arguments that it +requires, and the type of information that it returns.</p> +</div> +<div class="paragraph"> +<p>When we perform a function call on an attribute, as above, we refer to the attribute as the +<em>subject</em> of the function, as the attribute is the entity on which the function is operating. +We can then chain together multiple function calls, where the return value of the first function +becomes the subject of the second function and its return value becomes the subject of the third +function and so on. Continuing with our example, we can chain together multiple functions by using +the expression <code>${filename:toUpper():equals('HELLO.TXT')}</code>. There is no limit to the number of +functions that can be chained together.</p> +</div> +<div class="paragraph"> +<p>Any FlowFile attribute can be referenced using the Expression Language. However, if the attribute +name contains a “special character,” the attribute name must be escaped by quoting it. The following +characters are each considered “special characters”:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p>$ (dollar sign)</p> +</li> +<li> +<p>| (pipe)</p> +</li> +<li> +<p>{ (open brace)</p> +</li> +<li> +<p>} (close brace)</p> +</li> +<li> +<p>( (open parenthesis)</p> +</li> +<li> +<p>) (close parenthesis)</p> +</li> +<li> +<p>[ (open bracket)</p> +</li> +<li> +<p>] (close bracket)</p> +</li> +<li> +<p>, (comma)</p> +</li> +<li> +<p>: (colon)</p> +</li> +<li> +<p>; (semicolon)</p> +</li> +<li> +<p>/ (forward slash)</p> +</li> +<li> +<p>* (asterisk)</p> +</li> +<li> +<p>' (single quote)</p> +</li> +<li> +<p>(space)</p> +</li> +<li> +<p>\t (tab)</p> +</li> +<li> +<p>\r (carriage return)</p> +</li> +<li> +<p>\n (new-line)</p> +</li> +</ul> +</div> +<div class="paragraph"> +<p>Additionally, a number is considered a “special character” if it is the first character of the attribute name. +If any of these special characters is present in an attribute is quoted by using either single or double quotes. +The Expression Language allows single quotes and double quotes to be used interchangeably. For example, the following +can be used to escape an attribute named “my attribute”: <code>${"my attribute"}</code> or <code>${'my attribute'}</code>.</p> +</div> +<div class="paragraph"> +<p>In this example, the value to be returned is the value of the "my attribute" value, if it exists. If that attribute +does not exist, the Expression Language will then look for a System Environment Variable named "my attribute." If +unable to find this, it will look for a JVM System Property named "my attribute." Finally, if none of these exists, +the Expression Language will return a <code>null</code> value.</p> +</div> +<div class="paragraph"> +<p>There also exist some functions that expect to have no subject. These functions are invoked simply +by calling the function at the beginning of the Expression, such as <code>${hostname()}</code>. These functions +can then be changed together, as well. For example, <code>${hostname():toUpper()}</code>. Attempting to +evaluate the function with subject will result in an error. In the <a href="expression-language-guide.html#functions">Functions</a> +section below, these functions will clearly indicate in their descriptions that they do not +require a subject.</p> +</div> +<div class="paragraph"> +<p>Often times, we will need to compare the values of two different attributes to each other. +We are able to accomplish this by using embedded Expressions. We can, for example, check if +the “filename” attribute is the same as the “uuid” attribute: <code>${filename:equals( ${uuid} )}</code>. +Notice here, also, that we have a space between the opening parenthesis for the <code>equals</code> method and +the embedded Expression. This is not necessary and does not affect how the Expression is evaluated +in any way. Rather, it is intended to make the Expression easier to read. White space is ignored by +the Expression Language between delimiters. Therefore, we can use the Expression +<code>${ filename : equals(${ uuid}) }</code> or <code>${filename:equals(${uuid})}</code> and both Expressions +mean the same thing. We cannot, however, use <code>${file name:equals(${uuid})}</code>, because this results +in <code>file</code> and <code>name</code> being interpreted as different tokens, rather than a single token, <code>filename</code>.</p> +</div> +</div> +</div> +<div class="sect1"> +<h2 id="usage"><a class="anchor" href="expression-language-guide.html#usage"></a>Expression Language in the Application</h2> +<div class="sectionbody"> +<div class="paragraph"> +<p>The Expression Language is used heavily throughout the NiFi application for configuring Processor +properties. Not all Processor properties support the Expression Language, however. Whether or not +a Property supports the Expression Language is determined by the developer of the Processor when +the Processor is written. However, the application strives to clearly illustrate for each Property +whether or not the Expression Language is supported.</p> +</div> +<div class="paragraph"> +<p>In the application, when configuring a Processor property, the User Interface provides an Information +icon ( +<span class="image"><img src="images/iconInfo.png" alt="Info"></span> +) next to the name of the Property. Hovering over this icon with the mouse will provide a tooltip that +provides helpful information about the Property. This information includes a description of the Property, +the default value (if any), historically configured values (if any), and whether or not this Property +supports the expression language.</p> +</div> +<div class="sect2"> +<h3 id="editor"><a class="anchor" href="expression-language-guide.html#editor"></a>Expression Language Editor</h3> +<div class="paragraph"> +<p>When configuring the value of a Processor property, the NiFi User Interface provides help with the +Expression Language using the Expression Language editor. Once an Expression is begin by typing <code>${</code>, +the editor begins to highlight parentheses and braces so that the user is easily able to tell which +opening parenthesis or brace matches which closing parenthesis or brace.</p> +</div> +<div class="paragraph"> +<p>The editor also supplies context-sensitive help by providing a list of all functions that can be used +at the current cursor position. To activate this feature, press Ctrl+Space on the keyboard. The user +is also able to type part of a function name and then press Ctrl+Space to see all functions that can +be used that start with the same prefix. For example, if we type into the editor <code>${filename:to</code> +and then press Ctrl+Space, we are provided a pop-up that lists six different functions: <code>toDate</code>, +<code>toLower</code>, <code>toNumber</code>, <code>toRadix</code>, <code>toString</code>, and <code>toUpper</code>. We can then continue typing to narrow +which functions are shown, or we can select one of the functions from the list by double-clicking +it with the mouse or using the arrow keys to highlight the desired function and pressing Enter.</p> +</div> +</div> +</div> +</div> +<div class="sect1"> +<h2 id="functions"><a class="anchor" href="expression-language-guide.html#functions"></a>Functions</h2> +<div class="sectionbody"> +<div class="paragraph"> +<p>Functions provide a convenient way to manipulate and compare values of attributes. The Expression Language +provides many different functions to meet the needs of a automated dataflow. Each function takes +zero or more arguments and returns a single value. These functions can then be chained together to create +powerful Expressions to evaluate conditions and manipulate values. See <a href="expression-language-guide.html#structure">Structure of a NiFi Expression</a> for more information +on how to call and chain functions together.</p> +</div> +<div class="sect2"> +<h3 id="types"><a class="anchor" href="expression-language-guide.html#types"></a>Data Types</h3> +<div class="paragraph"> +<p>Each argument to a function and each value returned from a function has a specific data type. The Expression +Language supports four different data types:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><strong>String</strong>: A String is a sequence of characters that can consist of numbers, letters, white space, and +special characters.</p> +</li> +<li> +<p><strong>Number</strong>: A Number is an integer comprised of one or more digits (<code>0</code> through <code>9</code>). The Expression Language +does not provide support for fractional numbers. Dates and times are represented in the +Expression Language as Numbers, representing the number of milliseconds since midnight GMT on January 1, 1970.</p> +</li> +<li> +<p><strong>Boolean</strong>: A Boolean is one of either <code>true</code> or <code>false</code>.</p> +</li> +</ul> +</div> +<div class="paragraph"> +<p>All attributes are considered to be of type String.</p> +</div> +<div class="paragraph"> +<p>The Expression Language is generally able to automatically coerce a value of one data type to the appropriate +data type for a function. However, functions do exist to manually coerce a value into a specific data type. +See the <a href="expression-language-guide.html#type_cast">Type Coercion</a> section for more information.</p> +</div> +</div> +</div> +</div> +<div class="sect1"> +<h2 id="boolean"><a class="anchor" href="expression-language-guide.html#boolean"></a>Boolean Logic</h2> +<div class="sectionbody"> +<div class="paragraph"> +<p>One of the most powerful features of the Expression Language is the ability to compare an attribute value against +some other value. This is used often, for example, to configure how a Processor should route data. The following +functions are used for performing boolean logic, such as comparing two values. +Each of these functions returns a value of type Boolean.</p> +</div> +<div class="sect2 function"> +<h3 id="isnull"><a class="anchor" href="expression-language-guide.html#isnull"></a>isNull</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">The <code>isNull</code> function returns <code>true</code> if the subject is null, <code>false</code> otherwise. This is typically used to determine +if an attribute exists.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">Any</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>: No arguments</p> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">Boolean</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: <code>${filename:isNull()}</code> returns <code>true</code> if the "filename" attribute does not exist. + It returns <code>true</code> if the attribute exists.</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="notnull"><a class="anchor" href="expression-language-guide.html#notnull"></a>notNull</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">The <code>notNull</code> function returns the opposite value of the <code>isNull</code> function. That is, it will return <code>true</code> if the +subject exists and <code>false</code> otherwise.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">Any</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>: No arguments</p> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">Boolean</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: <code>${filename:notNull()}</code> returns <code>true</code> if the "filename" attribute exists. It returns "false" if the attribute + does not exist.</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="isempty"><a class="anchor" href="expression-language-guide.html#isempty"></a>isEmpty</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">The <code>isEmpty</code> function returns <code>true</code> if the Subject is null or contains only white-space + (new line, carriage return, space, tab), <code>false</code> otherwise.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>: No arguments</p> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">Boolean</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: <code>${filename:isEmpty()}</code> returns <code>true</code> if the "filename" attribute does not exist or contains only + white space.</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="equals"><a class="anchor" href="expression-language-guide.html#equals"></a>equals</h3> +<div class="paragraph description"> +<p><strong>Description</strong>: <span class="description">The <code>equals</code> function is very widely used and determines if its subject is equal to another String value. + Note that the <code>equals</code> function performs a direct comparison of two String values. Take care not to confuse this + function with the <a href="expression-language-guide.html#matches">matches</a> function, which evaluates its subject against a Regular Expression.</span></p> +</div> +<div class="paragraph subject"> +<p><strong>Subject Type</strong>: <span class="subject">Any</span></p> +</div> +<div class="paragraph arguments"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>value</em></span> : <span class="argDesc">The value to compare the Subject to. Must be same type as the Subject.</span></p> +</li> +</ul> +</div> +<div class="paragraph returnType"> +<p><strong>Return Type</strong>: <span class="returnType">Boolean</span></p> +</div> +<div class="paragraph examples"> +<p><strong>Examples</strong>: +We can check if the filename of a FlowFile is "hello.txt" by using the expression <code>${filename:equals('hello.txt')}</code>, +or we could check if the value of the attribute <code>hello</code> is equal to the value of the <code>filename</code> attribute: +<code>${hello:equals( ${filename} )}</code>.</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="equalsignorecase"><a class="anchor" href="expression-language-guide.html#equalsignorecase"></a>equalsIgnoreCase</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">Similar to the <code>equals</code> function, the <code>equalsIgnoreCase</code> function compares its subject against a String value but returns +<code>true</code> if the two values differ only by case (upper case vs. lower case).</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>value</em></span> : <span class="argDesc">The value to compare the Subject to.</span></p> +</li> +</ul> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">Boolean</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: <code>${filename:equalsIgnoreCase('hello.txt')}</code> will evaluate to <code>true</code> if filename is equal to "hello.txt" + or "HELLO.TXT" or "HeLLo.TxT".</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="gt"><a class="anchor" href="expression-language-guide.html#gt"></a>gt</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">The <code>gt</code> function is used for numeric comparison and returns <code>true</code> if the subject is Greater Than + its argument. If either the subject or the argument cannot be coerced into a Number, + this function returns <code>false</code>.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">Number</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>value</em></span> : <span class="argDesc">The number to compare the Subject to.</span></p> +</li> +</ul> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">Boolean</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: <code>${fileSize:gt( 1024 )}</code> will return <code>true</code> if the size of the FlowFile’s content is more than 1 kilobyte + (1024 bytes). Otherwise, it will return <code>false</code>.</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="ge"><a class="anchor" href="expression-language-guide.html#ge"></a>ge</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">The <code>ge</code> function is used for numeric comparison and returns <code>true</code> if the subject is Greater Than + Or Equal To its argument. If either the subject or the argument cannot be coerced into a Number, + this function returns <code>false</code>.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">Number</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>value</em></span> : <span class="argDesc">The number to compare the Subject to.</span></p> +</li> +</ul> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">Boolean</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: <code>${fileSize:ge( 1024 )}</code> will return <code>true</code> if the size of the FlowFile’s content is at least ( + is greater than or equal to) 1 kilobyte (1024 bytes). Otherwise, it will return <code>false</code>.</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="lt"><a class="anchor" href="expression-language-guide.html#lt"></a>lt</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">The <code>lt</code> function is used for numeric comparison and returns <code>true</code> if the subject is Less Than + its argument. If either the subject or the argument cannot be coerced into a Number, + this function returns <code>false</code>.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">Number</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>value</em></span> : <span class="argDesc">The number to compare the Subject to.</span></p> +</li> +</ul> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">Boolean</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: <code>${fileSize:lt( 1048576 )}</code> will return <code>true</code> if the size of the FlowFile’s content is less than + 1 megabyte (1048576 bytes). Otherwise, it will return <code>false</code>.</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="le"><a class="anchor" href="expression-language-guide.html#le"></a>le</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">The <code>le</code> function is used for numeric comparison and returns <code>true</code> if the subject is Less Than + Or Equal To its argument. If either the subject or the argument cannot be coerced into a Number, + this function returns <code>false</code>.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">Number</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>value</em></span> : <span class="argDesc">The number to compare the Subject to.</span></p> +</li> +</ul> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">Boolean</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: <code>${fileSize:le( 1048576 )}</code> will return <code>true</code> if the size of the FlowFile’s content is at most + (less than or equal to) 1 megabyte (1048576 bytes). Otherwise, it will return <code>false</code>.</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="and"><a class="anchor" href="expression-language-guide.html#and"></a>and</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">The <code>and</code> function takes as a single argument a Boolean value and returns <code>true</code> if both the Subject + and the argument are <code>true</code>. If either the subject or the argument is <code>false</code> or cannot be coerced into a Boolean, + the function returns <code>false</code>. Typically, this is used with an embedded Expression as the argument.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">Boolean</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>condition</em></span> : <span class="argDesc">The right-hand-side of the <em>and</em> Expression</span></p> +</li> +</ul> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">Boolean</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: We can check if the filename is both all lower-case and has at least 5 characters by using the Expression</p> +</div> +<div class="listingblock"> +<div class="content"> +<pre>${filename:toLower():equals( ${filename} ):and( + ${filename:length():ge(5)} +)}</pre> +</div> +</div> +</div> +<div class="sect2 function"> +<h3 id="or"><a class="anchor" href="expression-language-guide.html#or"></a>or</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">The <code>or</code> function takes as a single argument a Boolean value and returns <code>true</code> if either the Subject + or the argument is <code>true</code>. If both the subject and the argument are <code>false</code>, the function returns <code>false</code>. If + either the Subject or the argument cannot be coerced into a Boolean value, this function will return <code>false</code>.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">Boolean</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>condition</em></span> : <span class="argDesc">The right-hand-side of the <em>and</em> Expression</span></p> +</li> +</ul> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">Boolean</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: The following example will return <code>true</code> if either the filename has exactly 5 characters or if + the filename is all lower-case.</p> +</div> +<div class="listingblock"> +<div class="content"> +<pre>${filename:toLower():equals( ${filename} ):or( + ${filename:length():equals(5)} +)}</pre> +</div> +</div> +</div> +<div class="sect2 function"> +<h3 id="not"><a class="anchor" href="expression-language-guide.html#not"></a>not</h3> +<div class="paragraph description"> +<p><strong>Description</strong>: <span class="description">The <code>not</code> function returns the negation of the Boolean value of the subject.</span></p> +</div> +<div class="paragraph subject"> +<p><strong>Subject Type</strong>: <span class="subject">Boolean</span></p> +</div> +<div class="paragraph arguments"> +<p><strong>Arguments</strong>: No arguments</p> +</div> +<div class="paragraph returnType"> +<p><strong>Return Type</strong>: <span class="returnType">Boolean</span></p> +</div> +<div class="paragraph examples"> +<p><strong>Examples</strong>: We can invert the value of another function by using the <code>not</code> function, as + <code>${filename:equals('hello.txt'):not()}</code>. This will return <code>true</code> if the filename is NOT equal to + "hello.txt" and will return <code>false</code> if the filename is "hello.txt."</p> +</div> +</div> +</div> +</div> +<div class="sect1"> +<h2 id="strings"><a class="anchor" href="expression-language-guide.html#strings"></a>String Manipulation</h2> +<div class="sectionbody"> +<div class="paragraph"> +<p>Each of the following functions manipulates a String in some way.</p> +</div> +<div class="sect2 function"> +<h3 id="toupper"><a class="anchor" href="expression-language-guide.html#toupper"></a>toUpper</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">This function converts the Subject into an all upper-case String. Said another way, it + replaces any lowercase letter with the uppercase equivalent.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>: No arguments</p> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: If the "filename" attribute is "abc123.txt", then the Expression <code>${filename:toUpper()}</code> + will return "ABC123.TXT"</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="tolower"><a class="anchor" href="expression-language-guide.html#tolower"></a>toLower</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">This function converts the Subject into an all lower-case String. Said another way, + it replaces any uppercase letter with the lowercase equivalent.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>: No arguments</p> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: If the "filename" attribute is "ABC123.TXT", then the Expression <code>${filename:toLower()}</code> + will return "abc123.txt"</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="trim"><a class="anchor" href="expression-language-guide.html#trim"></a>trim</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">The <code>trim</code> function will remove any leading or trailing white space from its subject.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>: No arguments</p> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: If the attribute <code>attr</code> has the value " 1 2 3 ", then the Expression <code>${attr:trim()}</code> will + return the value "1 2 3".</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="urlencode"><a class="anchor" href="expression-language-guide.html#urlencode"></a>urlEncode</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">Returns a URL-friendly version of the Subject. This is useful, for instance, when using an + attribute value to indicate the URL of a website.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>: No arguments</p> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: We can URL-Encode an attribute named "url" by using the Expression <code>${url:urlEncode()}</code>. If + the value of the "url" attribute is "https://nifi.incubator.apache.org/some value with spaces", this + Expression will then return "https://nifi.incubator.apache.org/some%20value%20with%20spaces";.</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="urldecode"><a class="anchor" href="expression-language-guide.html#urldecode"></a>urlDecode</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">Converts a URL-friendly version of the Subject into a human-readable form.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>: No arguments</p> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: If we have a URL-Encoded attribute named "url" with the value + "https://nifi.incubator.apache.org/some%20value%20with%20spaces";, then the Expression + <code>${url:urlDecode()}</code> will return "https://nifi.incubator.apache.org/some value with spaces".</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="substring"><a class="anchor" href="expression-language-guide.html#substring"></a>substring</h3> +<div class="paragraph"> +<p><strong>Description</strong>: +<span class="description">Returns a portion of the Subject, given a <em>starting index</em> and an optional <em>ending index</em>. + If the <em>ending index</em> is not supplied, it will return the portion of the Subject starting at the given + <em>start index</em> and ending at the end of the Subject value.</span></p> +</div> +<div class="paragraph"> +<p><span class="description">The <em>starting index</em> and <em>ending index</em> are zero-based. That is, the first character is referenced by using + the value <code>0</code>, not <code>1</code>.</span></p> +</div> +<div class="paragraph"> +<p><span class="description">If either the <em>starting index</em> is or the <em>ending index</em> is not a number, this function call will result + in an error.</span></p> +</div> +<div class="paragraph"> +<p><span class="description">If the <em>starting index</em> is larger than the <em>ending index</em>, this function call will result in an error.</span></p> +</div> +<div class="paragraph"> +<p><span class="description">If the <em>starting index</em> or the <em>ending index</em> is greater than the length of the Subject or has a value + less than 0, this function call will result in an error.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>starting index</em></span> : <span class="argDesc">The 0-based index of the first character to capture (inclusive)</span></p> +</li> +<li> +<p><span class="argName"><em>ending index</em></span> : <span class="argDesc">The 0-based index of the last character to capture (exclusive)</span></p> +</li> +</ul> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>:</p> +</div> +<div class="paragraph"> +<p>If we have an attribute named "filename" with the value "a brand new filename.txt", +then the following Expressions will result in the following values:</p> +</div> +<table class="tableblock frame-all grid-all spread"> +<caption class="title">Table 1. Substring Examples</caption> +<colgroup> +<col style="width: 50%;"> +<col style="width: 50%;"> +</colgroup> +<tbody> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock">Expression</p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock">Value</p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substring(0,1)}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>a</code></p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substring(2)}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>brand new filename.txt</code></p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substring(12)}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>filename.txt</code></p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substring( ${filename:length():minus(2)} )}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>xt</code></p></td> +</tr> +</tbody> +</table> +</div> +<div class="sect2 function"> +<h3 id="substringbefore"><a class="anchor" href="expression-language-guide.html#substringbefore"></a>substringBefore</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">Returns a portion of the Subject, starting with the first character of the Subject + and ending with the character immediately before the first occurrence of the argument. If + the argument is not present in the Subject, the entire Subject will be returned.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>value</em></span> : <span class="argDesc">The String to search for in the Subject</span></p> +</li> +</ul> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: If the "filename" attribute has the value "a brand new filename.txt", + then the following Expressions will result in the following values:</p> +</div> +<table class="tableblock frame-all grid-all spread"> +<caption class="title">Table 2. SubstringBefore Examples</caption> +<colgroup> +<col style="width: 50%;"> +<col style="width: 50%;"> +</colgroup> +<tbody> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock">Expression</p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock">Value</p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substringBefore('.')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>a brand new filename</code></p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substringBefore(' ')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>a</code></p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substringBefore(' n')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>a brand</code></p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:sbustringBefore('missing')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>a brand new filename.txt</code></p></td> +</tr> +</tbody> +</table> +</div> +<div class="sect2 function"> +<h3 id="substringbeforelast"><a class="anchor" href="expression-language-guide.html#substringbeforelast"></a>substringBeforeLast</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">Returns a portion of the Subject, starting with the first character of the Subject + and ending with the character immediately before the last occurrence of the argument. If + the argument is not present in the Subject, the entire Subject will be returned.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>value</em></span> : <span class="argDesc">The String to search for in the Subject</span></p> +</li> +</ul> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: [.returnType]#String3</p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: If the "filename" attribute has the value "a brand new filename.txt", + then the following Expressions will result in the following values:</p> +</div> +<table class="tableblock frame-all grid-all spread"> +<caption class="title">Table 3. SubstringBeforeLast Examples</caption> +<colgroup> +<col style="width: 50%;"> +<col style="width: 50%;"> +</colgroup> +<tbody> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock">Expression</p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock">Value</p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substringBeforeLast('.')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>a brand new filename</code></p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substringBeforeLast(' ')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>a brand new</code></p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substringBeforeLast(' n')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>a brand</code></p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substringBeforeLast('missing')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>a brand new filename.txt</code></p></td> +</tr> +</tbody> +</table> +</div> +<div class="sect2 function"> +<h3 id="substringafter"><a class="anchor" href="expression-language-guide.html#substringafter"></a>substringAfter</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">Returns a portion of the Subject, starting with the character immediately after + the first occurrence of the argument and extending to the end of the Subject. If + the argument is not present in the Subject, the entire Subject will be returned.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>value</em></span> : <span class="argDesc">The String to search for in the Subject</span></p> +</li> +</ul> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: If the "filename" attribute has the value "a brand new filename.txt", + then the following Expressions will result in the following values:</p> +</div> +<table class="tableblock frame-all grid-all spread"> +<caption class="title">Table 4. SubstringAfter Examples</caption> +<colgroup> +<col style="width: 50%;"> +<col style="width: 50%;"> +</colgroup> +<tbody> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock">Expression</p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock">Value</p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substringAfter('.')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>txt</code></p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substringAfter(' ')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>brand new filename.txt</code></p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substringAfter(' n')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>ew filename.txt</code></p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substringAfter('missing')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>a brand new filename.txt</code></p></td> +</tr> +</tbody> +</table> +</div> +<div class="sect2 function"> +<h3 id="substringafterlast"><a class="anchor" href="expression-language-guide.html#substringafterlast"></a>substringAfterLast</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">Returns a portion of the Subject, starting with the character immediately after + the last occurrence of the argument and extending to the end of the Subject. If + the argument is not present in the Subject, the entire Subject will be returned.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>value</em></span> : <span class="argDesc">The String to search for in the Subject</span></p> +</li> +</ul> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: If the "filename" attribute has the value "a brand new filename.txt", + then the following Expressions will result in the following values:</p> +</div> +<table class="tableblock frame-all grid-all spread"> +<caption class="title">Table 5. SubstringAfterLast Examples</caption> +<colgroup> +<col style="width: 50%;"> +<col style="width: 50%;"> +</colgroup> +<tbody> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock">Expression</p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock">Value</p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substringAfterLast('.')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>txt</code></p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substringAfterLast(' ')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>filename.txt</code></p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substringAfterLast(' n')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>ew filename.txt</code></p></td> +</tr> +<tr> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${filename:substringAfterLast('missing')}</code></p></td> +<td class="tableblock halign-left valign-top"><p class="tableblock"><code>a brand new filename.txt</code></p></td> +</tr> +</tbody> +</table> +</div> +<div class="sect2 function"> +<h3 id="append"><a class="anchor" href="expression-language-guide.html#append"></a>append</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">The <code>append</code> function returns the result of appending the argument to the value of + the Subject. If the Subject is null, returns the argument itself.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>value</em></span> : <span class="argDesc">The String to append to the end of the Subject</span></p> +</li> +</ul> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: If the "filename" attribute has the value "a brand new filename.txt", then the Expression + <code>${filename:append('.gz')}</code> will return "a brand new filename.txt.gz".</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="prepend"><a class="anchor" href="expression-language-guide.html#prepend"></a>prepend</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">The <code>prepend</code> function returns the result of prepending the argument to the value of + the Subject. If the subject is null, returns the argument itself.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>value</em></span> : <span class="argDesc">The String to prepend to the beginning of the Subject</span></p> +</li> +</ul> +</div> +<div class="paragraph"> +<p><strong>Return Type</strong>: <span class="returnType">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Examples</strong>: If the "filename" attribute has the value "filename.txt", then the Expression + <code>${filename:prepend('a brand new ')}</code> will return "a brand new filename.txt".</p> +</div> +</div> +<div class="sect2 function"> +<h3 id="replace"><a class="anchor" href="expression-language-guide.html#replace"></a>replace</h3> +<div class="paragraph"> +<p><strong>Description</strong>: <span class="description">Replaces occurrences of one String within the Subject with another String.</span></p> +</div> +<div class="paragraph"> +<p><strong>Subject Type</strong>: <span class="subject">String</span></p> +</div> +<div class="paragraph"> +<p><strong>Arguments</strong>:</p> +</div> +<div class="ulist"> +<ul> +<li> +<p><span class="argName"><em>Search String</em></span> : <span class="argDesc">The String to find within the Subject</span></p> +</li> +<li> +<p><span class="argName"><em>Replacement</em></span> : <span class="argDesc">The value to replace <em>Search String</em> with</span></p>
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