What are Form Controllers? 

• Form controllers in Zoho SalesIQ are used to modify the fields in a form and to process the data filled in the form.
  
• When a user adds or updates an input value in a form field or clicks the submit or cancel button in the form, the form function associated with this function is triggered to execute the intended action. 

Benefits of Form Controllers:

• Forms can be used as a part of a widget's action response to collect data from your operator and push the data to any application. 
  
• Forms in SalesIQ support dynamic input fields updating when the operator is interacting with the form, support searching through a list from database and dynamically show then in the field's dropdown based on the search keyword.
  

Handlers in Form Controllers:

• Whenever a form is submitted, the default action is considered for the Submit button. If the Cancel button action is not handled in the function code, all the input values will be cancelled by default and the form will not return any response. It can have three different outputs:
  
• banner
  
• section_edit
  
• form_error
  
• The parameters available in this handler are operator, environment and form.
  

• The change handler is invoked for an update made in any form field containing the boolean trigger_on_change as true. 
  
• The change handler can be used to either add, remove or update fields in the form depending on the input made for a certain field. 
  
• The parameters available in this handler are operator, environment, form, and target.
  

• The dynamic field handler is associated with the dynamic-select field type. 
  
• This handler is invoked to populate the drop-down menu items for the field based on the user input. The list of menu items to be populated in the drop-down is configured in this handler as a comma separated value list and the search trigger works based on the following criteria:
  
• starts-with 
  
• contains
  
• The parameters available in this handler are operator, environment, form, and target.