问题
I'm struggling to implement a fairly trivial functionality with JSF which involves dynamically displaying the content of a nested map on a page and editing capabilities for its values. But it has turned out that the MappedValueExpression$Entry that you get when iterating over a map with c:forEach is not writable!
<c:forEach items='#{inflectionBean.word.inflectionalForms}' var="number" >
<p:fieldset legend="#{number.key}">
<c:forEach items="#{number.value}" var="case" >
<p:panel header="#{case.key}">
<h:inputText value="#{case.value}" />
</p:panel>
</c:forEach>
</p:fieldset>
</c:forEach>
When I am trying to submit the above form I'm getting:
javax.el.PropertyNotWritableException: /inflection.xhtml @39,56 value="#{case.value}": The class 'com.sun.faces.facelets.tag.jstl.core.MappedValueExpression$Entry' does not have a writable property 'value'.
I wonder if there are reasonable workarounds or if I am approaching the problem in a wrong way. Thanks!
回答1:
Basically, what your code is attempting is invoking Map.Entry#setValue(value). This is indeed not possible in EL. Instead, you should be referencing the map value directly on the map itself by key, so that EL can do Map#put(key, value).
<c:forEach items="#{number.value}" var="case">
...
<h:inputText value="#{number.value[case.key]}" />
来源：https://stackoverflow.com/questions/17977578/how-to-set-a-map-value-in-hinputtext