How to throw an exception in Azure Logic Apps?

Question

Is it possible to throw an exception in a Logic App?

Specifically, I'm trying to throw an exception inside of a scope. Then in the run after of the scope I'd check if it failed and inspect it for errors. I tried using a terminate inside of a scope, but that terminates the entire logic app run.

Answer 1

Quick Answer (TL;DR)

• Problem: MSFT Azure logic app throwing exceptions
• Workaround: Use logic app Scope element to simulate throwing exceptions
  • Create a scope element to use as your "try-catch" block
  • Force the scope element to fail with an invalid command to simulate an exception
  • Allow the scope element to fail naturally and that will count as an exception too

Detailed Answer

Context

• MSFT Azure logic app workflows
• live version as of 2020-06-14

Problem

• Scenario: Developer wishes to throw an exception or use try-catch semantics in a logic app

Solution

• As of this writing, the live version of the product does not support this feature. There is a workaround.

Workaround

• Use logic app scope element
• add a conditional statement inside the scope element
• If the conditional statement meets the failure condition, force an exception with a deliberately invalid command
  • for example create a variable assignment with the value int('__ERROR__')
• If the conditional statement does not meet the failure condition, do nothing
• The rest of the logic app consists of two paths
  • The first path runs on the success of the scope element
  • The second path runs on the failure of the scope element (failed, skipped, timed out)

Example

• Create a scope element as a "try-catch" block

• Create a variable compose element with an invalid command

    
    int('__ERROR__')  ## this will cause the enclosing scope to fail
                      ## the string __ERROR__ cannot be cast to integer

• Respond to exit status of the Scope element enclosing your exception

See also

• related SO answer about forcing exceptions https://stackoverflow.com/a/61101945/42223