Field injection with Execution Listener

Camunda 7 Topics Discussion & Questions
1

I am trying to implement a Listener with a field injection.

I call a ExecutionListener via Delegate Expression, which is found correctly. I set a Field Injection field with a name, as Type String, with a value.

In my code the injection is referenced to as Type Expression. I try to call the String value with getValue(execution).toString();in the Listeners notify-method, but i always get a NullPointerException, because the injected Object is always null.

Any Ideas of why this fails? I´ve done field injections often with service or send tasks but never with listeners. Is there any difference i should be aware of?

Thx in advance!

2

I did a workaround by using an expression instead. But it seems ugly.

3

Hi @BenF,

Have you followed the documentation here: https://docs.camunda.org/manual/latest/user-guide/process-engine/delegation-code/#field-injection when configuring the field injection?

If yes, can you provide the code and bpmn process, or at least the part that relates to the problem?

Best,
Nikola

4

Hi all, it’s an older post but I needed the same functionality for ExecutionListener and ended up with NPEs. @nikola.koevski 's note to follow the documentation was the key to solve the issue:
You have to use the type Expression for the injected field even if you inject just a String. Then you can call:

fieldName.getValue(execution).toString();

One should still check against NPs if the same Listener is used in the BPMN without field injection or injection result depends on other variables etc.

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