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https://issues.apache.org/struts/browse/STR-2330?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Paul Benedict updated STR-2330:
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Fix Version/s: Future
Assignee: (was: Struts Developers)
> [taglib] Struts tags must check attribute values using isEmpty(), not against
> nulls
> -----------------------------------------------------------------------------------
>
> Key: STR-2330
> URL: https://issues.apache.org/struts/browse/STR-2330
> Project: Struts 1
> Issue Type: Improvement
> Components: Taglibs
> Affects Versions: 1.2.6 Beta
> Environment: Operating System: All
> Platform: PC
> Reporter: Firepica
> Priority: Minor
> Fix For: Future
>
> Attachments: normalize-in-setter.patch.txt
>
>
> There is an architectural problem with Struts tags used in tag files.
> As you know, in every Struts tag decision on whether attribute has a value set
> is based on comparison to null. Example:
> if (accesskey != null) {
> results.append(" accesskey=\"");
> results.append(accesskey);
> results.append("\"");
> }
> Where "accesskey" is an attribute of html:select tag.
> The following example shows why usage of Struts tags is substantially
> restricted
> in tag files because of that feature.
> The following "icon" tag renders a hyperlink based on "type" attribute (say,
> "remove" or "add"), displaying corresponding icon. It has 2 mutually exclusive
> attributes: "action" and "href" and one optional attribute "onclick".
> === icon.tagx begins ===
> <?xml version="1.0" encoding="UTF-8"?>
> <jsp:root xmlns:jsp="http://java.sun.com/JSP/Page";
> xmlns:html="http://struts.apache.org/tags-html"; version="2.0" >
> <jsp:directive.tag body-content="empty"/>
> <jsp:directive.attribute name="type" required="true" rtexprvalue="true" />
> <jsp:directive.attribute name="action" required="false" rtexprvalue="true"
> />
> <jsp:directive.attribute name="href" required="false" rtexprvalue="true" />
> <jsp:directive.attribute name="onclick" required="false" rtexprvalue="true"
> />
> <html:link action="${action}">
> <html:img page="images/${type}.gif" border="0"/>
> </html:link>
> </jsp:root>
> === icon.tagx ends ===
> Question here is how should we invoke html:link tag based on value of the
> attributes? Ok, we could use <c:choose> like:
> <c:choose>
> <c:if test="${not empty action}">
> <!-- use value of action atribute -->
> <html:link action="${action}">
> <html:img page="images/${type}.gif" border="0"/>
> </html:link>
> </c:if>
> <c:otherwise>
> <!-- use value of href atribute -->
> <html:link href="${href}">
> <html:img page="images/${type}.gif" border="0"/>
> </html:link>
> </c:otherwise>
> </c:choose>
> this would be correct if we had only "action" and "href", but we also have
> "onclick". That means, that in every if/otherwise section we need to add same
> check for presence of "onclick" attribute. If we had not 3 but 10 attributes,
> then total number of <if> statements would be 2^9 which is far beyond
> reasonable
> limits.
> The most obvious and conscious solution would be to use the following
> construction instead:
> <html:link action="${action}" href="${href}" onclick="${onclick}">
> <html:img page="images/${type}.gif" border="0"/>
> </html:link>
> So if icon tag is invoked via <my:icon action="/Action" type="add"/> then
> "href"
> and "onclick" attributes would be nulls and, say, href="${href}" will not
> change
> the default value (null) of the html:link "href" property (call setHref(null);
> on tag handler). But this is not true because EL evaluates nulls into empty
> strings, so what happens is that html:link tag receives empty (not null)
> "href"
> and "onclick" properties which produces an error message (setHref(""); on tag
> handler).
> The solution would be to make Struts to check attributes for emptiness (like
> StringUtils.isEmpty(), i.e. == null or ""), not just for nulls. Then it would
> work.
> Example:
> if (StringUtils.isNotEmpty(accesskey)) {
> results.append(" accesskey=\"");
> results.append(accesskey);
> results.append("\"");
> }
> Where StringUtils is from jakarta commons lang package.
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