Get submitted form value for a task when the task is multi instance

My task is reference to a form, and this task is multi instance. I know that submit a form will auto store in to process variables, so multi instance task’s form data will conflicted? and this task will appear in flow multi times. my question is how to get submitted form data for a specific task by taskId?


check the image above, review1 and review2 reference to same form, and they boths multi instance.

You can use variable aggregation for this, see here Multi Instance Variable Aggregation (even though this is the enterprise version, the same applies to the open source engine).

Variable aggregation can’t find source value from task localScope. I complete a task with variables in local scope, aggregation’s target value is empty.

Variable aggregation also can’t map a serializable value

I get another question, what is variable type of aggregation, I get json and bpmnAggregation in database table ACT_RU_VARIABLE, what are the differences between these two types.