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jspstruts2iteratorognlstruts-tags

Using <s:set /> to dynamically build element's name

I want to reuse a set of HTML field elements and have struts build 'name' attributes from a variable. I saw this How To Generate unique HTML id attributes within Struts 2 iterator tag and figured I could use something similar but can't get it to work. It seems I can build a name attribute from a struts variable only in an iterator loop. How can I do this with a simple variable instead?

Here is my code, first trying to use a variable, the second using an iterator :

<s:set var="type" value="Main" />
<s:textfield name="prefix%{#type}.Name"/>

<s:set var="AList" value="{'Main'}" />
<s:iterator value="AList" var="Ltype">
    <s:textfield name="prefix%{#Ltype}.Name"/>
</s:iterator>

This generates 2 elements :

<input type="text" name="prefix.Name"     value="">
<input type="text" name="prefixMain.Name" value="">

with the first not substituting the variable, and the iterator loop working.

Why doesn't it work and how can I do this?

Solution

  • You are assigning a value to the first variable, not a String literal, and since there isn't an object called Main in your ValueStack, you are assigning an empty String to the type variable:

    <s:set var="type" value="Main" />

    while you are doing it (almost) great in the second example:

    <s:set var="AList" value="{'Main'}" />

    Just use 

    <s:set var="AList" value="%{'Main'}" />

    or 

    <s:set var="AList" value="'Main'" />

    everywhere and it will work.

    {} alone is useless and dangerous, because it has a special meaning in OGNL (list projection, list selection, etc.)