Overview
Using the Field Rules, you can choose to 
show or hide certain form fields to your respondents or 
set certain fields as mandatory to fill in based on their previous responses on the form. This way, you can let your respondents see only the fields that are relevant to them by minimizing the questions that are irrelevant to them, or get input for the mandatory fields, and personalize and streamline the form filling experience for each respondent.
For example, if a user answers "Yes" to a question about whether they are a vegetarian, the form may display a series of questions about their dietary preferences and if the user chooses "No," the form may skip those irrelevant questions and move on to the next.
Field Rules in Zoho Forms can be configured for both basic and 
advanced scenarios.
Before we understand how Field Rules work, let us first understand what AND, OR connectors mean in Rules.
AND: If you require all the conditions in a rule to be satisfied at the same time to perform the intended action, use the AND operator.  
OR: If you require at least one of the conditions in a rule to be satisfied to perform the action, use the OR operator. 
Field Rules can be used in scenarios where actions are taken when all or any of the defined conditions are met. 
Assume you have three requirements (Condition 1, Condition 2, and Condition 3) to execute Action 1 and Action 2.
You can setup Field Rules to perform the actions when: 
                - All the 3 conditions are satisfied:  
 
              If Condition 1 AND Condition 2 AND Condition 3 are true -> then perform Action 1 and Action 2. 
                - Any of the 3 conditions are satisfied: 
 
              If Condition 1 OR Condition 2 OR Condition 3 are true -> then perform Action 1 and Action 2.
Show/Hide fields with conditional rules
To show or hide certain fields based on a defined set of conditions, you can use Field Rules. 
For example, assume you have a Room Reservation Form where you want to display the 
Additional Charges Applied only when your customers require additional services like, a room with a riverview, extra bedding, or a chauffeur for pick up. 
 
        
To configure Field Rules to Show/Hide fields, 
- After building your form, navigate to the Rules tab.     
 
- Under Field Rules, click Configure Now. 
  
 
- Define your conditions in the If section by choosing your form fields and the criterion they must satisfy. To add more than one condition, click the icon. icon.
- A rule can be executed if at least one of the defined conditions is satisfied or if all of the conditions are satisfied. To define this, choose AND/OR connectors between your conditions. Click the connector to switch between AND / OR. 
 
- In the  Then- section, choose the action  Show- or  Hide- fields and select the required fields in the  Search Fields- box to show up or hide fields in your form when the defined set of conditions are satisfied. Click the  -  icon to define more than one action.  
 
 
-   - If your use-case requires the use of AND and OR operators within the conditions of the same rule, you can  switch to Advanced Rules- . Note that once you switch, all the Field Rules you will configure for your form moving forward will be in the Advanced Rule format.  
- Once you have configured the rule(s), click Add to save and view the rule summary. 
  
 
- To add more rules, click  in the top right corner. in the top right corner.
 
- To filter rules, click the filter icon in the top-right corner.  
 
Using Grouped Choices with conditional rules
You can configure field rules to work with 
grouped choices of a dropdown field. 
To do so,  
- Go to Rules > Field Rules and click Configure Now.     
 
- Define your conditions in the If section by choosing your form fields and the criterion they must satisfy. To add more than one condition, click the icon. icon.
- A rule can be executed if at least one of the defined conditions is satisfied or if all of the conditions are satisfied. To define this, choose AND/OR connectors between your conditions. Click the connector to switch between AND / OR.
- Under Then section, you can choose between Show Grouped Choices or Hide Grouped Choices. 
 
 
- Click Add to view the rule summary.
 
- To add more rules, click  in the top right corner. in the top right corner.
 
- To filter rules, click the filter icon in the top-right corner. 
 
Set Fields as Mandatory with conditional rules
Although you can choose certain fields to be mandatory in the Properties pane of the respective fields on your form builder, you can make certain fields as mandatory if the set conditions are satisfied.
For example, assume you have an Event Registration form, and if your respondent chooses to bring guests, you can make the number of guests field mandatory in order to get a head count.
To configure Field Rules to set fields as mandatory,
- After building your form, navigate to the Rules tab.
 
 
- Under Field Rules, click Configure Now.
  
 
- Define your conditions in the If section by choosing your form fields and the criterion they must satisfy. To add more than one condition, click the icon. icon.
- A rule can be executed if at least one of the defined conditions is satisfied or if all of the conditions are satisfied. To define this, choose AND/OR connectors between your conditions. Click the connector to switch between AND / OR.
 
- 
                    
                        In the  Thensection, choose the action  Set Fields as Mandatoryand select the required fields when the defined set of conditions are satisfied. Click the   icon to define more than one action.   
 
- Once you have configured the rule(s), click Add to save and view the rule summary.
 
- To add more rules, click  in the top right corner. in the top right corner.
 
- To filter rules, click the filter icon in the top-right corner. 
Note:
- The fields involved with the Set Fields as Mandatory action cannot be marked as mandatory in the field properties of the form builder.
 
- Fields that have been marked as mandatory in the form builder properties will not available to use with the Set Fields as Mandatory action in the Field Rules.
 
- The Set Fields As Mandatory action is supported only if you have switched to Advanced Rules.
Restrictions while configuring Field Rules
- A Condition field should come prior to the Action field in the form builder for the rule to work.
 
 - For example, if you have configured a Field Rule to show the  Email- field only when the user chooses the mode of communication to be  Email- :  
- In the above rule,
 
 - Condition field -> Mode of communication
 
 - Action field -> Email
 For this rule to work, the Condition field ( Mode of communication ) should come prior to the Action field ( Email ) in your form.
 - If you try to change the position of these fields in the form such that Email field comes prior to the Mode of Communication field, you will encounter an error.
 
 
 
 
- Except for the Set Fields as Mandatory action of the Field Rules, subform fields cannot be used to configure the conditions or actions.
 
  Note : To set Field Rules by comparing the values of two fields within a form, use Field-to-Field Comparison in Advanced Rules. Learn more Note : To set Field Rules by comparing the values of two fields within a form, use Field-to-Field Comparison in Advanced Rules. Learn more
 
 
 
Supported Operators
- Is: Checks if the selected field is equal to the set value
- Is Not: Checks if the selected field is not equal to the set value
- Is Empty: Checks if the selected field is empty
- Is Not Empty: Checks if the selected field is not empty
- Contains: Checks if the selected field contains a value in the condition
- Not Contains: Checks if the selected field does not contain a value in the condition 
 
- Contains Any Of: Checks if a field contains any of the selected choices
- Contains All Of: Checks if a field contains all of the selected choices
- Contains None Of: Checks if a field contains none of the selected choices
- Starts With: Checks if the selected field starts with the given value
- Ends With: Checks if the selected field ends with the given value 
 
- Other Choice Is Not Empty: Checks if a value is entered in the Other choice
- Is Any Of: Checks if any of the choices chosen in the condition match
- 
                    Is None Of: Checks if none of the choices chosen in the condition match  
 
 
- 
                    Less Than: Checks if a number is less than a given value 
- 
                    Greater Than: Checks if a number is greater than a given value 
- 
                    Less Than or Equal To: Checks if a number is less than or equal to a given value 
- 
                    Greater Than or Equal To: Checks if a number is greater than or equal to a given value 
- 
                    Between: Checks if a number/date is between 2 given values  
 
 
- 
                    True:  Checks if logical TRUE value is returned 
- 
                    False: Checks if logical FALSE value is returned 
The following table lists the operators that can be used with the corresponding field types to form a rule criteria in the If section: 
                
                    
                        |    Field Types |    Supported Operators | 
                    
                        | Name |    Contains Not Contains
 Is Empty
 Is Not Empty
 | 
                    
                        | Single Line Multi Line
 Phone
 
 |    Is Is Not
 Is Empty
 Is Not Empty
 Contains
 Not Contains
    Starts With 
    Ends With  
 | 
                    
                        | Number Decimal
 Currency
 Rating
 Formula
 
 |    Is Is Not
 Is Empty
 Is Not Empty
    Less Than 
    Greater Than 
    Less Than or Equal To 
    Greater Than or Equal To 
    Between  
 | 
                    
                        | Address |    Contains Not Contains
    Is Empty 
    Is Not Empty | 
                    
                        | Email Website
 |    Is  
    Is Not  
    Is Empty  
    Is Not Empty  
    Starts With 
    Ends With  
 | 
                    
                        | Date Date-Time
 |    Is  Is Not
 Is Empty
 Is Not Empty
    Less Than 
    Greater Than  
    Between  
 | 
                    
                        | Time |    Is  Is Not
 Is Empty
 Is Not Empty
    Less Than 
    Greater Than | 
                    
                        | Decision Box Terms and Conditions
 |    True 
    False  
 | 
                    |
                    
                        | Radio Dropdown
 |    Is Is Not
 Is Empty
 Is Not Empty
    Starts With 
    Ends With 
    Other Choice Is Not Empty 
    Is Any Of 
    Is None Of  
 | 
 | 
                    
                        | Multiple Choice Checkbox
 Image Choices
 |    Contains Not Contains
 
    Is Empty Is Not Empty
 Contains Any Of
 Contains All Of
 Contains None Of
 | 
 | 
                    
                        | Matrix     Choice | Is Is Not
 Is Empty
 Is Not Empty
 | 
                    
                        | Slider |    Is 
    Is Not    Less Than 
    Greater Than 
    Less Than or Equal To 
    Greater Than or Equal To 
    Between  
 | 
                    
                        | Signature | Is Empty Is Not Empty
 | 
 |