Multiple Required Field Validator

With this workflow post-function, you can ensure that a given field as a certain value

To add 'Required Field Validator' to a transition: 

1. Click Edit for the workflow that has the transition you wish to add the validator on.
2. In the Workflow Designer, select the transition.
3. Click on Validator in the properties panel.
4. Click on Add validator.
5. Select Required Field Validator from the list of validators.
6. Click on Add to add the validator on the transition.
7. Fill the form shown below and press 'Add' button.

Fields

Required Field – Set here the source field which you want to force a certain value

Required Value – The value for the source field in order to validate against

Error Message – Set here the message you want to display o users when this validation fails.