List of Apex-Defined wrapper output from Flow is not iterable in Apex class

Question

I have a flow that returns the List to the Apex class. The apex class is the REST API that try to convert the output as JSON it returns null, so I have tried to iterate the list to assign the another wrapper to convert that as string.

 List<CustomWrapper> lstWrapper = ( List<CustomWrapper> )contFlow.varOutput;

It throws following error:

System.QueryException: Dynamic query yields incompatible SObject type java:interaction.engine.interview.FlowApexObject for loop variable of type CustomWrapper

It works fine when I pass the output as List of sObjects.

Answer 1

There is a workaround that you can apply easily.

Since we can get String value as output from flows, you can serialize your Apex-defined variable and set it as output. Later grab that output (String) and deserialize to your original object which Apex-defined type class.

Just create and add a new Apex class (input Apex-defined type and output List) to your flow for serialization before setting output.

Answer 2

The only potential answer I can provide is from the documentation here : https://help.salesforce.com/articleView?id=flow_considerations_apex_data_type.htm&type=0

It specifies that "An Apex-defined variable value can't be set or stored outside the flow." This suggests that you can't store the flow variable to an apex representation. Even if they are supposed to be of the same class.