How to validate values instantly, but check for re

问题:

I am currently adding validation to a form. There are two things to check: The correctness of the value itself (e.g. if it is a positive integer or valid email) and whether all required fields were filled in.

However, if by some means (f:ajax or IceFaces partialSubmit attribute) I make the validation for type correctness happen at once (e.g. when the field loses focus), it will also check the required attribute in this same step. In most cases this is no problem, as the user already entered a value and is likely to correct it rather than go back to a blank field.

However, in the case where he actually wants to clear the field again, he can no longer do so without getting an error. In consequence, I only want to check the required-ness of fields on finally submitting the page.

At the moment, my only idea to separate the two validation types is by performing all required-checks in the backing beans action method, thus tying it to directly to the final submit via button.

Is there another way?

(For background: The reason why one might want to clear the field again is that requirements can change depending on other selections in the form. So one might decide to not provide this field after all and only after that correct the option that actually makes this field optional.)

回答1:

Just let the required attribute evaluate true when the submit button has really been pressed.

The answer however depends on the way how your submit button executes its logic (standard, f:ajax, ICEfaces, etc). But it basically boils down to that you could check the request parameter map for a request parameter which indicates that the desired submit button has been pressed.

E.g., if it's a standard command button:

<h:form id="form">
    ...
    <h:commandButton id="submit" value="Submit" action="#{bean.submit}" />
</h:form>

Then you could check for it by checking if the button's client ID is present in the request parameter map:

<c:set var="submitButtonPressed" value="#{not empty param['form:submit']}" />
...
<h:inputText ... required="#{submitButtonPressed}" />
<h:inputText ... required="#{submitButtonPressed}" />
<h:inputText ... required="#{submitButtonPressed}" />

Or, if it's a <f:ajax> button:

<h:form id="form">
    ...
    <h:commandButton id="submit" value="Submit" action="#{bean.submit}">
        <f:ajax execute="@form" ... />
    </h:commandButton>
</h:form>

Then you could check it by checking if javax.faces.source parameter equals the button's client ID:

<c:set var="submitButtonPressed" value="#{param['javax.faces.source'] == 'form:submit'}" />
...
<h:inputText ... required="#{submitButtonPressed}" />
<h:inputText ... required="#{submitButtonPressed}" />
<h:inputText ... required="#{submitButtonPressed}" />

You could even combine both:

<c:set var="submitButtonPressed" value="#{not empty param['form:submit'] or param['javax.faces.source'] == 'form:submit'}" />
...
<h:inputText ... required="#{submitButtonPressed}" />
<h:inputText ... required="#{submitButtonPressed}" />
<h:inputText ... required="#{submitButtonPressed}" />