How to let validation depend on the pressed button?

问题

I have created form and I want to show previous existing items on a table while a new one is creating. I'd like to show matching items as form is filling up. But when I try to filter the list without having the form completed, the validation messages appear and the table doesn't get updated.

Don't know if it's possible, but what I want to do something like this:

<h:form id="form">

    <h:outputText value="Name: "/>
    <p:inputText value="#{itemsBean.name}" id="name" required="true"/>
    <br/>
    <h:outputText value="Description: "/>
    <p:inputText value="#{itemsBean.description}" id="description" required="true"/>

    <p:commandButton value="Save" update="form" actionListener="#{itemsBean.save}"/> //validate and save
    <p:commandButton value="Filter" update="form" actionListener="#{itemsBean.updateItemsList}"/> //don't validate, and update the table.

    <p:dataTable id="list" value="#{itemsBean.itemsList}" var="item">     
        <p:column>
            <h:outputText value="#{item.name}"/>
        </p:column>
        <p:column>
            <h:outputText value="#{item.description}"/>
        </p:column>
    </p:dataTable>

</h:form>

I'm very new to JSF.

回答1:

I understand that you want to filter based on the name input field. The <p:commandButton> sends by default an ajax request and has a process attribute wherein you can specify which components you'd like to process during the submit. In your particular case, you should then process only the name input field and the current button (so that its action will be invoked).

<p:commandButton process="@this name" ... />

The process attribute can take a space separated collection of (relative) client IDs of the components, wherein @this refers to the current component. It defaults in case of <p:commandButton> to @form (which covers all input fields of the current form and the pressed button), that's why they were all been validated in your initial attempt. In the above example, all other input fields won't be processed (and thus also not validated).

If you however intend to skip the required validation for all fields whenever the button in question is been pressed, so that you can eventually process multiple fields which doesn't necessarily need to be all filled in, then you need to make the required="true" a conditional instead which checks if the button is been pressed or not. For example, let it evaluate true only when the save button has been pressed:

<p:inputText ... required="#{not empty param[save.clientId]}" />
...
<p:inputText ... required="#{not empty param[save.clientId]}" />
...
<p:commandButton binding="#{save}" value="Save" ... />

This way it won't be validated as required="true" when a different button is pressed. The trick in the above example is that the name of the pressed button (which is essentially the client ID) is been sent as request parameter and that you could just check its presence in the request parameter map.

See also:

• Understanding PrimeFaces process/update and JSF f:ajax execute/render attributes

回答2:

I Have tested this with non-ajax submits:

<p:inputText ... required="#{not empty param.includeInSave1}" />
...
<p:inputText ... required="true" />
...
<p:commandButton value="Save1" ajax="false">
  <f:param name="includeInSave1" value="true" />
</p:commandButton>

<p:commandButton value="Save2" ajax="false" />

The first input is required validated only on Save1 button submit.

回答3:

Additionally to the BalusC answer (very useful and complete) I want to add that when you use a <h:commandButton /> it will validate (required, custom validations) all the fields in the <h:form /> where the command button is located, therefore when you need to use more than one command button you could consider that it is a good practice to use different <h:form /> to different responsibilities to avoid unexpected behavior in submit actions of the command buttons. It is well explained in a BalusC answer: Multiple h:form in a JSF Page

If your form has validations and you do not update the <h:form /> or you do not show messages, you could get a headache thinking that the <h:commandButton /> is not firing your action, but likely is a validation problem that has not been shown.

回答4:

Change your filter commandbutton like this to ignore validation:

<p:commandButton value="Filter" update="list" actionListener="#{itemsBean.updateItemsList}" process="@this"/>

EDIT:

The related post on SO, I think this will solve your issue too

JSF 2.0: How to skip JSR-303 bean validation?

来源：https://stackoverflow.com/questions/8370675/how-to-let-validation-depend-on-the-pressed-button