Description
This filter fires on the Form Editor page when a field button is clicked or dragged on to the form, it can be used to prevent a field being added to the form if the conditions you define are not met.
Usage
gform.addFilter( 'gform_form_editor_can_field_be_added', function ( canFieldBeAdded, type) {
// return false to prevent a field being added.
return canFieldBeAdded;
} );
Example
gform.addFilter('gform_form_editor_can_field_be_added', function (canFieldBeAdded, type) {
if (type !== 'your_custom_type') {
return canFieldBeAdded;
}
if (GetFieldsByType(['product']).length <= 0) {
alert('You must add a Product field to the form first');
return false;
} else if (GetFieldsByType(['your_custom_type']).length) {
alert('Only one [your field type here] field can be added to the form');
return false;
}
return canFieldBeAdded;
});
Source Code
This filter is located in js.php
Placement
Reference the article Adding JavaScript Code to the Admin Side of Your Site.