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pythondjangoworkflowdjango-viewflow

viewflow.io: What is the recommended pattern to go a step back in a flow?

With the ViewFlow library (see http://viewflow.io/), I'm looking at the following use case:

While stepping through a Flow, what is the recommended pattern to step back? Right now I only found out how to step forward (which is the default behaviour). But what about the usecase were I want to update/change the input gathered during a previous step?

Solution

  • If updating data is not the part of the process, it could be implemented as usual django view. Nothing special required here.

    If it is the part of process, it's always moving forward, and all process decisions recorded and could be used in flow gateways. In this case you should have two explicit tasks, one for data input, another one for data validation, and IF gateway to check validation status.

    I could recommend for you to became familiar with BPMN notation and practice. Viewflow resembles them directly.

    enter image description here

    If you would like to have a next task undo and cancel functionality, you can implement custom view action.

    # cancel current task
activation = current_task.activate()
if activation.undo.can_proceed():
   activation.undo()
   activation.cancel()

# allow to re-execute previous task
activation = previous_task.activate()
if activation.undo.can_proceed():
   activation.undo()