Server Side Validation - computing the required parameter to a viewScope - xpages

Question

I'm having an issue with some server side validation and I can't tell if this is the expected behavior in XPages or if I'm missing something simple here.
I have a field that has a computed validation formula - basically, it becomes required when a viewScope variable gets set.
My submit button sets the viewScope and does a full refresh.
I would expect the form to be submitted, the validation formula gets evaluated, and if it fails the validation failure would be displayed. But when I click my submit button the form is submitted without error. If I click it again, validation fails as expected.
To illustrate my issue I created a simple example:
<xp:inputText id="inputText1" required="#{javascript:viewScope.validate}">
<xp:this.validators>
<xp:validateRequired message="This field is required."></xp:validateRequired>
</xp:this.validators>
</xp:inputText>
 
<xp:button value="Submit" id="button1">
<xp:eventHandler event="onclick" submit="true"
refreshMode="complete" immediate="false" save="true">
<xp:this.action><![CDATA[#{javascript:viewScope.validate=true;}]]></xp:this.action>
<xp:this.script><![CDATA[dojo.attr(dojo.byId("#{id:inputText1}"),"aria-required","true")]]></xp:this.script>
</xp:eventHandler>
</xp:button>
<xp:br></xp:br>
<xp:message id="message1" for="inputText1"></xp:message>
As you can see, I also tried adding the aria-required attribute with csjs within the button in the hopes it would initiate validation.
If validation is working as expected are there any suggestions for getting dynamic validation like this to function properly? I know I can do something with querySave on the data source (I excluded a data source from the example for simplicity) but was hoping there is a simpler solution than that.

Answer 1

It looks like the problem is misunderstanding the lifecycle. You're specifying whether the field is required in a viewScope variable. When the page is first loaded, the viewScope is false, so the field is not required. After you submit, the viewScope variable is set, the page rendered again. Only now does the field become required, but it is only required the next time the form is submitted.
If you want the field to be required, you'll need the required property to be evaluated to true and passed to the browser before the form is submitted.
There are a number of alternatives for the functionality you're trying to manage, running SSJS and failing if certain criteria are met.
One is to use the validator property rather than calculating the required property. The validator allows you to run code but you will need to use this.getSubmittedValue() to check the field's value - the validator runs earlier in the lifecycle before the submittedValue is passed to the value property.
The second option is to put the validation in the Submit button. You can use facesContext.addMessage(). If you google xpages facesContext addMessage there are plenty of examples of how to do it. Then do "return false" to abort.

Answer 2

It looks like you might want conditional validation. I wrote a blogpost about this a while back:
Making validation behave properly