Question

I want a field to become required only when a specific option is selected or a specific radio button is selected or when a specific string is entered in a text input field (All of the required( dependency-expression ) examples I can find assume that the dependency is whether an input is checked / unchecked or filled/unfilled in the case of text fields)

Here is an example of what I need, based on a radio section:

Marital Status (the required field):

<input name="status" id='status'type="radio" value="couple" checked="checked" />
<input name="status" id='status'type="radio" value="single male"  />
<input name="status" id='status'type="radio" value="single female" />

Partners Name (the dependent field – required only when ‘Couple’ is selected from above)

<input name="partner" type="text"  id="partner">

Example 2: Required field = Venue

<select name="venue" id="venue">
<option value="">Please select venue</option>
<option>London EC1</option>
<option>London E9</option>
<option>Birmingham</option>

etc.
Dependent field = user (only required for one of the above selections, say ‘Birmingham’)

<input name="user" type="text" id="user">

How do I adapt the example shown athttp://docs.jquery.com/Plugins/Validation/Methods/required#dependency-expression for the above situations?

$("#myform").validate({
  rules: {
    details: {
      required: "#other:checked"
    }
  }, debug:true
});
$("#other").click(function() {
  $("#details").valid();
});

I have tried:

user: {
      required: "#venue:('birmingham')"
    }

and

partner: {
      required: "#status:('couple')"
    }

but these have the effect of making user and partner required regardless of results in venue and status

Answer 1

For the first one, your radio inputs should have different id’s:

<input name="status" id='statusCouple' type="radio" value="couple" checked="checked" />
<input name="status" id='statusSingleMale' type="radio" value="single male"  />
<input name="status" id='statusSignleFemale' type="radio" value="single female" /> 

Then your rule can look like this:

partner: {
  required: "#statusCouple:checked"
}

For the second one, just make your rule like this:

user: {
  required: function(element) { return $("#venue").val() == 'Birmingham'; }
}       

Should do the trick.