Question

I’m designing dynamic forms for grails and I was wondering if it was at possible to set the widget constraint dynamically?

Answer 1

Setting the widget constraint is not the way to attack this. I suppose the simplest method would be to choose the tag you’d like to display based upon some condition using an “if” tag in your view or template. For instance:

Say you have a Book

class Book {

    String name

}

If you use Grails generate-view for this class, Grails will produce a template called _form that looks like the following:

<div class="fieldcontain ${hasErrors(bean: bookInstance, field: 'name', 'error')} ">
    <label for="name">
        <g:message code="book.name.label" default="Name" />

    </label>
    <g:textField name="name" value="${bookInstance?.name}"/>
</div>

You can test your condition in this form and change the view:

<div class="fieldcontain ${hasErrors(bean: bookInstance, field: 'name', 'error')} ">
        <label for="name">
            <g:message code="book.name.label" default="Name" />

        </label>

            <g:if test="$yourCondition">
                <g:textField name="name" value="${bookInstance?.name}"/>
            </g:if>
            <g:else>
                <g:textArea name="name"  value="${bookInstance?.name}"/>
            </g:else>
    </div>

Now the view will display a textField or textArea field based upon $yourCondition.