如何使用f：ajax在jsf结构的不同部分中呈现事物

Question

The concise version of the question I have is this: How do I in response of a blur event on a

<h:inputText> 

get the same value to show in a

<h:outputText> 

located outside the scope of the inputText field.

The inputtext field has the following xpath:

//*[@id="form:j_idt40:src_table:0:j_idt137"]

The outputtext is located here:

//*[@id="form:j_idt40:target_table:0:target_id"]

I am using primefaces datatable and the two paths are located in two separate datatables

The jsf code for the input field is the following:

<p:dataTable id="src_table">
    <p:column id="src_id" headerText="srcHeader">
        <h:inputText value="#{bean.myAttribute}">
            <f:ajax event="blur" render="src_id WHAT_SHOULD_GO_HERE?" ></f:ajax>
        </h:inputText>
    </p:column>
</p:datatable>

and the code for the output is the following

<p:dataTable id="target_table">
    <p:column headerText="TargetHeader">
        <h:outputText id="target_id" value="#{bean.myAttribute}" />
    </p:column>
</p:datatable>

i have tried several paths on the WHAT_SHOULD_GO_HERE? placeholder but I can't seem to get it right. They have all ended up throwing faces exceptions like the following:

javax.faces.FacesException: <f:ajax> contains an unknown id ':target_id' - cannot locate it in the context of the component j_idt137

this was of course when I replaced WHAT_SHOULD_GO_HERE? with :target_id

I have also tried:

form:j_idt40:target_table:0:target_id, 

:form:j_idt40:target_table:0:target_id 

but no luck.

Can anyone help with my understanding of xpath or maybe even f:ajax and rendering specific parts of a view?

Answer 1

Can anyone help with my understanding of xpath

JSF doesn't use Xpath in <f:ajax> at all. It just expects a relative or absolute client ID. This is in detail explained in How to find out client ID of component for ajax update/render? Cannot find component with expression "foo" referenced from "bar" .

You should only change the component represented by the autogenerated ID j_idt40 to have a fixed ID set, otherwise it would break again when you add or remove a component in the view later.