Trigger JSF validation using ajax after focus lost

How do you trigger validation on an input component when the component loses f开发者_如何学JAVAocus using ajax instead of waiting for the form to be manually submitted?

Put a <f:ajax event="blur"> in the UIInput component which re-renders a <h:message> associated with the component in question.

<h:inputText id="foo" value="#{bean.foo}" required="true">
    <f:ajax event="blur" render="fooMessage" />
</h:inputText>
<h:message id="fooMessage" />

See also JSF 2.0 tutorial with Eclipse and Tomcat - the view and finetuning validation

Try this code:

<h:inputText value="#{bean.value}" valueChangeListener="#{bean.validateValue}">
    <f:ajax event="blur" render="valueError"/>
</h:inputText>

<h:outputText id="valueError" value="#{bean.valueErrorMessage}" style="color: red;" />

If the user changes the value in your input component you can validate it with your valueChangeListener. If the user then moves to another input component the ouputText component will be rendered. There you can display a message if the validation failed.