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Using id = "# {...}" raises java.lang.IllegalArgumentException: empty id attribute is not allowed

I need to solve my problem with generating a dynamic identifier for some components in JSF.

Take a look at this example:

<h:outputText id="#{bean.id}" value="#{bean.value}" />

My problem is that I get this error:

 java.lang.IllegalArgumentException: Empty id attribute is not allowed

The component id is empty when I look at the generated HTML output. How is this caused and how can I solve it?

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1 answer

You're right. I use it inside datatable.

Then this can happen if #{bean} represents the current iterated object declared in the var attribute as follows:

 <h:dataTable value="#{someBean.beans}" var="bean"> <h:column> <h:outputText id="#{bean.id}" value="#{bean.value}" />

The id (and binding ) attribute of the JSF component is evaluated during build time, at the moment the JSF component tree is to be compiled. However, #{bean} is available only during time rendering, at a time when <h:dataTable> needs to <h:dataTable> over all objects and generate HTML table rows for each of them. Thus, #{bean} unavailable during build time and evaluates to null , which ultimately gets the forced EL value to an empty string. And therefore the java.lang.IllegalArgumentException: Empty id attribute is not allowed exception java.lang.IllegalArgumentException: Empty id attribute is not allowed .

You have basically 3 options:

  • Instead, use the view build time tag to iterate over the collection. You just need to write the whole HTML template:

     <table> <c:forEach items="#{someBean.beans}" var="bean"> <tr> <td> <h:outputText id="#{bean.id}" value="#{bean.value}" />

  • Use a simple HTML element:

     <h:dataTable value="#{someBean.beans}" var="bean"> <h:column> <span id="#{bean.id}">#{bean.value}</span>

  • Do not set a dynamic identifier, but a fixed identifier. JSF will ensure the uniqueness of HTML output by adding it with the table row index:

     <h:dataTable value="#{someBean.beans}" var="bean"> <h:column> <h:outputText id="id" value="#{bean.value}" />

See also:

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Source: https://habr.com/ru/post/893946/

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