How can I conditionally require form inputs with AngularJS?

Question

Suppose we're building an address book application (contrived example) with AngularJS.

We have a form for contacts that has inputs for email and phone number, and we want to require one or the other, but not both: We only want the email input to be required if the phone input is empty or invalid, and vice versa.

Angular has a required directive, but it's not clear from the documentation how to use it in this case. So how can we conditionally require a form field? Write a custom directive?

Answer 1

For conditionally require form inputs with AngularJS, you no need to write a custom directive. Angular's documentation is good but not complete. In fact, there is a directive and ngRequired, 

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that takes an Angular expression. See the code below:-

<input type='email' 

name='email' 

ng-model='contact.email' 

placeholder='[email protected]' 

ng-required='!contact.phone' /> 

<input type='text' 

ng-model='contact.phone' 

placeholder='(xxx) xxx-xxxx' 

ng-required='!contact.email' />