========
required
========

.. js:attribute:: required

**domain**: client 

**language**: javascript

**class** :doc:`Field class </refs/client/field_api>`


Description
===========

Specifies whether a not empty value for a field is required.

Use **required** to find out if a field requires a value or if the field can be 
blank. When **required** property is set to true, trying to post a null value 
will cause an exception to be raised.


See also
========

:doc:`Fields </programming/data/fields>`

:doc:`read_only <at_read_only>`