[WW-4036] With javatemplate, dynamic attribute value evaluates to expression text if null

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.3.12
• Fix Version/s: 2.3.15
• Component/s: Plugin - Java Templates
• Assignee: Lukasz Lenart
• Reporter: Walid Ghafir
• Created: 04/Apr/13 00:02
• Updated: 24/Jun/13 09:24
• Resolved: 24/May/13 14:40

Description

When using javatemplate plugin, if a dynamic attribute has an expression value that evaluates to null, the full expression text is displayed instead of just an empty string.

Example:

<s:textfield placeholder="%{null}" name="%{null}"/> 

will output

<input type="text" placeholder="%{null}" name=""/> 

in the HTML.

By debugging, I found it comes from AbstractUITag.setDynamicAttribute():

dynamicAttributes.put(localName, String.valueOf(ObjectUtils.defaultIfNull(findValue(value.toString()), value)));

That problem does not occur with FTL themes as dynamic-attributes.ftl uses TextParseUtil.translateVariables() which does what the doc says ("If an item cannot be found on the stack (null is returned), then the entire variable %{...} is not displayed, just as if the item was on the stack but returned an empty string.").

Suggested fix #1

Change org.apache.struts2.views.java.simple.DynamicAttributesHandler.start() so that it does the same than dynamic-attributes.ftl:

DynamicAttributesHandler.java

    @Override
    public void start(String name, Attributes a) throws IOException {
	Map<String, String> dynamicAttributes = (Map<String, String>) context.getParameters().get("dynamicAttributes");
	for (String key : dynamicAttributes.keySet())
		a.put(key, TextParseUtil.translateVariables(dynamicAttributes.get(key), context.getStack()));
        super.start(name, a);
    }

Suggested fix #2

Or change org.apache.struts2.views.jsp.ui.AbstractUITag.setDynamicAttribute() so that it returns an empty string if the expression evaluates to null:

AbstractUITag.java

    public void setDynamicAttribute(String uri, String localName, Object value) throws JspException {
        if (ComponentUtils.altSyntax(getStack()) && ComponentUtils.isExpression(value)) {
            dynamicAttributes.put(localName, String.valueOf(ObjectUtils.defaultIfNull(findValue(value.toString()), "")));
        } else {
            dynamicAttributes.put(localName, value);
        }
    }

(but I have no idea on the possible side effects it could produce).