JSF field highlighting with ajax posts?

Question

I'm building on BalusC's solution to highlight and focus fields in JSF. My plan is to output a JSON array with ids and then have a method be called which will process this array. This works fine when I don't use <f:ajax/>

Here is my phase listener solution:

public void beforePhase(PhaseEvent event) {
    FacesContext facesContext = event.getFacesContext();
    List<String> highlightFields = new ArrayList<String>();

    Iterator<String> highlightFieldsItr = facesContext
            .getClientIdsWithMessages();
    while (highlightFieldsItr.hasNext()) {
        StringBuilder sb = new StringBuilder();
        sb.append("#");
        sb.append(highlightFieldsItr.next().replaceAll(":", "\\\\:"));
        highlightFields.add(sb.toString());
    }
    JSONArray jsonHighlightFields = new JSONArray(highlightFields);

    facesContext.getExternalContext().getRequestMap()
            .put("errorFields", jsonHighlightFields.toString());
}

Basically this would produce errorFields value with something like ["#some\:id1", "#some\id2"]. Then I can do something like this in my root layout file:

   <script>
     var errorFields = ${errorFields}; // This will xlate to ["#some\\:id1", "#some\\:id2"

     $(document).ready(function(){
         processInputErrors(errorFields);
     });
   </script>

With a processInputErrors function like this:

function processInputErrors(ids) {
    for (id in ids) {
        if (focus == false) {
            jQuery(ids[id]).focus();
            focus = true;
        }
        jQuery(ids[id]).addClass('input-error');
    }
}

However, I need to somehow obtain this list in the function which gets called on success of an ajax post.

Now f:ajax does have the onevent attribute and this function does get called, but I'm not sure exactly what it gets passed. How would I be able somehow pass the invalid Ids from the phase listener to this function? It seems to be passed an object which represents the HTMLInputElement?

  <f:ajax event="change" onevent="test" render="test test_msg" immediate="true" />

Happy to hear about alternative suggestions or ideas. The goal is basically to focus and highlight the field(s) which are invalid not only on a full post-back but also when using f:ajax.

Thanks!

score 3 · Accepted Answer · edited May 23 '17 at 12:12

That article was more targeted on JSF 1.x. JSF 2.x offers now a lot of advantages of which the following are beneficial for your particular requirement:

You can refer the current component in EL by #{component}. In case of input components this is the UIInput which in turn has an isValid() method. This could be used in styleClass attribute.
You can use <f:ajax> to re-render parts of the view, also <script> elements.

1+1 is...

<h:inputText id="input1" value="#{bean.input1}" required="true" styleClass="#{component.valid ? '' : 'error'}">
    <f:ajax render="@this input1message focus" />
</h:inputText> 
<h:message id="input1message" for="input1" />
...
<h:inputText id="input2" value="#{bean.input2}" required="true" styleClass="#{component.valid ? '' : 'error'}">
    <f:ajax render="@this input2message focus" />
</h:inputText> 
<h:message id="input2message" for="input2" />
...
<h:panelGroup id="focus"><script>jQuery(":input.error:first").focus();</script></h:panelGroup>

No need for a PhaseListener anymore. You could if necessary wrap the input markup boilerplate in a composite component or a tag file.

Back to your concrete question about the onevent attribute, check this answer: JSF 2: How show different ajax status in same input?

I see the the XML response from the ajax post has an tag which would be just executed. How would I be able to insert some javascript into the response back? Seems that the spec supports it but don't know how I would accomplish it. — jr., Sep 03 '11 at 23:18
When using a composite component, if the `panelGroup` exists outside of the `cc:implementation` of the component then the `focus` id attribute cannot be found. If there's a way to have the composite components reference the id attribute, an example to support this answer would be most helpful. — Dave Jarvis, Aug 15 '17 at 18:14

JSF field highlighting with ajax posts?

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