add reference numbers - smbc-digital/form-builder GitHub Wiki
Generating Reference Numbers
Form builder can provide reference numbers if required. This is provided by a basic reference number provider implementation, in order for a form to generate numbers the GenerateReferenceNumber, GeneratedReferenceNumberMapping and ReferencePrefix values must be provided.
For example:
 {
       "FormName": "",
       "BaseURL": "",
       "StartPageUrl": "",
       "FirstPageSlug": "",
       "GenerateReferenceNumber": true,
       "GeneratedReferenceNumberMapping": "CaseReference",
       "ReferencePrefix": "TEST-",
   }
Reference number will be generated and added to form and pre-submit, this will use the GeneratedReferenceNumberMapping in the submitted answers, the generated portion of the reference number will be prefixed with the ReferencePrefix, in the example above a submission could look like;
{
  "CaseReference": "TEST-A1b2C3",
  ...
}
PLEASE NOTE - There is the possibility of generating duplicate reference numbers, it's wise to check the generated number hasn't been used previously.