Well, now I'm confused.
The below was always my understanding. Then, the last time that Team ND
got together, back in February, I mentioned this to Brendan, who thought
otherwise. He whipped up a little test project that seemed to prove this
wrong. At that point, I figured that my reliance on so-called sessioning
was where I was setting criteria in a DO in a button or href event method,
and then executing it after loading another page, but in the same web
event. Stuff in the same web event doesn't really use sessioning, even if
your use put/get(Any)UserSessionObject (as discussed in another thread, or
is it this one, can't keep track).
OK, I will have to do my own test project, and report the results.
-- Curt Springer, Team ND
At 03:09 PM 5/21/99 -0500, Shamdasani Nimmi-ANS004 wrote:
>Aby,
>
>Is this what you are looking for?
>
>-Nimmi
>
> ===============================================================>
>Class spider.database.$Package_Description$
>
>
>The WHERE Clause
>
>
>SELECT, UPDATE, and DELETE queries allow (and often require) that you
>specify
>criteria. The criteria define the subset of the database records to be
>retrieved
>or affected. The criteria are specified in the WHERE clause of the query. A
>common base class named CSpCriteriaSQLObject provides common functions for
>constructing queries and defines constant values.
>
>
>In order to support the 4GL functionality NetDynamics provides, the final
>WHERE
>clause (when automatically created) is constructed from 5 sub-elements:
>
>
>� Static Join - The joins you specify in the Studio for this data object
>using
>the Joins tab of the data object editor
>
>� Static Filter - The where criteria you specify in the Studio for this
>data
>object using the Where tab of the data object editor
>
>� QBE Dynamic Criteria - The criteria automatically added by the doQBE()
>method
>(or manually added by you)
>
>� DrillDown Dynamic Criteria - The criteria automatically added in some
>cases by
>the doAction() method (or manually added by you)
>
>� Join Dynamic Criteria - All criteria automatically added by the doJoin()
>and
>methods like executeAllUpdatingDataObjects() (or manually added by you)
>
>
>The first two parts (Static Join and Static Filter) are typically provided
>by
>the developer, and they tend to be fixed for all executions of this data
>object
>by all end users. In contrast, the three Dynamic Criteria types tend to
>change
>from one end user to another, and they may even change during the same end
>user's session. For example, if the end user searches for all customers
>living
>in England, the doQBE() method would add a QBE Dynamic Criterion:
>
>
>(Customers.Country = 'England')
>
>
>
>If the results of the query contain more than the requested number of rows
>in
>the output HTML, the end user may return after an unknown time period and
>press
>the <Next> button. Naturally, he/she would expect to see the next page of
>all
>customers that live in England. Between these two web events, another end
>user
>might "intrude" and search for customers whose first name begins with "Jo".
>In
>short, the dynamic parts of the the WHERE clause are automatically saved by
>each
>criteria data object as normal session objects. This is the mechanism
>NetDynamics uses so that it does not get confused in such cases.
>
>There is a predefined hierarchy between the three parts of a dynamic
>criteria:
>
>
>� QBE
>
>� Drill Down
>
>� Join
>
>
>Consequently, high level Java CP methods that need to clear one level
>automatically clear all levels below it.
>
>
>� doQBE() clears all dynamic criteria (QBE, Drill Down, and Join).
>
>� doAction() may clear the Drill Down (and Join) criteria.
>
>� doJoin() clears the Join part only.
>
>
>In some cases you may add dynamic criteria yourself, check the criteria
>automatically added by the system, clear some parts, and so on. The database
>package provides methods such as addDynamicCriterion(), getDynamicCriteria
>and
>clearDynamicCriteria() to perform such tasks.
>
>
>Warning: Changes that you make to the dynamic criteria affect only the
>current
>end user (since criteria are automatically stored as user session objects).
>Changes made to the other two parts of the WHERE clause (Static Join and
>Static
>Filter) affect all end users. They are member variables of data objects
>shared
>by all end users.
>
>-----Original Message-----
>From: Mathew, Aby [mailto:[EMAIL PROTECTED]]
>Sent: Friday, May 21, 1999 2:36 PM
>To: 'Curt Springer';
>[EMAIL PROTECTED]
>Subject: Re: [ND] Why do I have to execute the dataobject before calling
>i ts getValue()?
>
>
>Curt,
>
>I too spent a lot of my ND life thinking Dynamic Criteria are as trustworthy
>as instance variables, until I was corrected recently.
>
>From what I learned, even though dataObject.addDynamicCriterion() sounds
>like adding something to the DataObject instance, ND goes and keeps the
>stuff in a userSessionObject, so it stays for the same user for later use.
>This functionality seems to be crucial for the built-in handling of Next,
>Prev etc.
>
>I had read a detailed note on this, but not able to locate it. It was fairly
>recently, otherwise I would doubt myself.
>
>Regards,
>
>Aby
>
>> -----Original Message-----
>> From: Curt Springer [SMTP:[EMAIL PROTECTED]]
>> Sent: Friday, May 21, 1999 2:38 PM
>> To: [EMAIL PROTECTED]
>> Subject: Re: [ND] Why do I have to execute the dataobject before
>> calling its getValue()?
>>
>> see below
>>
>> At 11:02 AM 5/21/99 -0800, [EMAIL PROTECTED] wrote:
>> >Hi,
>> >
>> >If some one could clarify the following that will be great-
>> >
>> >My Case:
>> >I have a DO that is not bound to the page, I am calling it on
>> >the onBeforeDisplay event of the page and adding dynamic
>> >criterion to it to personalize the contents of the page
>> >(actually a listbox on the page) for the user. Now I want to use
>> >the same DO in onWebEvent of a button the page, regarding that I
>> >have following questions-
>> >1. Why do I have to call execute() method of the DO before
>> >calling its getValue()?
>>
>> execute() causes the SQL 'select' statement to be sent to the dbms and
>> results to be retrieved back. When the DO is bound to the page, the page
>> calls execute() automatically. When the DO is not bound, you have to do
>> it
>> yourself.
>>
>> >2. Can I be sure that the DO's dynamic criteria is still the same
>> >assuming multiple user sessions are active and provided I did
>> >not change the criteria any where else in the code? My understanding is
>> that- instances DOs are not shared between sessions.
>>
>> I must admit I took a long time to get this straight (pre-emptive
>> statement).
>>
>> Dynamic criteria in a DO are like member variables in a page object. They
>> hold for the life of a web event, i.e., from a page load or beginning of
>> button/href method, until a page is sent back to the browser (including
>> the
>> situation where you set criteria on a DO in a button event, then load
>> another page and execute the DO in that page's onBeforeLoad or
>> onBeforeDisplay event). And, at the outset of a web event, they must be
>> assumed to reflect work done in a previous web event using the same
>> object.
>>
>> At the beginning of a web event, the DO might have criteria set by another
>> page session. So before you add any dynamic criteria for the current page
>> session, you must execute clearDynamicCriteria on the DO. Then you can
>> add
>> your current criteria.
>>
>> Also, in case it was not clear above, in one web event, if you are in a
>> button event of PageA, and you call CSpider.getDataObject("DO"),
>> and then you load PageB, and in its onBeforeLoadEvent, you call the same
>> CSpider.getDataObject("DO"), you will get the same object.
>>
>> -- Curt Springer, Team ND
>>
>>
>> >
>> >Thanks in advance to all the noble souls who are gonna reply...
>> >
>> >Vishal
>> >_________________________________________________________________________
>> >
>> >For help in using, subscribing, and unsubscribing to the discussion
>> >forums, please go to: http://www.netdynamics.com/support/visitdevfor.html
>> >
>> >For dire need help, email: [EMAIL PROTECTED]
>> >
>> _________________________________________________________________________
>>
>> For help in using, subscribing, and unsubscribing to the discussion
>> forums, please go to: http://www.netdynamics.com/support/visitdevfor.html
>>
>> For dire need help, email: [EMAIL PROTECTED]
>_________________________________________________________________________
>
>For help in using, subscribing, and unsubscribing to the discussion
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>
>For dire need help, email: [EMAIL PROTECTED]
>_________________________________________________________________________
>
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>
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