User Story (Required on creation):

I can use an expression to reference a form handler bean on a start event or a user task. Currently, it is only possible to reference a FormHandler by providing the class name with the help of the property formHandlerClass.

Functional Requirements (Required before implementation):

A bean of type FormHandler can be referenced via JUEL Expression.

Technical Requirements (Required before implementation):

Solution ideas:

• The formHandlerClass property supports a JUEL expression to resolve a bean
  • Pros
    • Might be relatively simple to implement; see PR [1]
      • The code changes in the codebase are relatively straight-forward
    • Documentation effort is low
  • Cons
    • Might be confusing since the name suggests to reference a Java class
• A new property formHandlerDelegateExpression is added which allows resolving a bean via JUEL expression
  • Pros
    • Would be consistent with other properties (e.g., expression vs. delegateExpression, variableMappingClass vs. variableMappingDelegateExpression)
    • It is immediately clear what the property does just by looking at its name
  • Cons
    • Higher effort due to more code changes that need to be tested and more to document

Limitations of Scope (Optional):

Hints (Optional):

See PR of prototypical implementation [1]

Original Ticket submitted by reporter

Summary

User Task Form Submission Validation Delegate Support

Description

Currently you can set a From Key on a User Task.  This field supports expressions/delegation.

But there is no support for Validation of the Form Submission.

It would be great if a additional config was added to user task called something like "Form Submission Delegate", which would route the form submission to the delegate for validation.

The internals of the api and code flow would be near identical to the internals/private apis of the Form Field Validation capabilities, but would move it to the public api level as a delegate.

Benefit: People could configure form validation and thus control submission of data. 

[1] https://github.com/camunda/camunda-bpm-platform/pull/1401