'Execute Pipeline' activity fails to pass a parameter of array type to child pipeline

Question

Hello,

I have designed a pipeline which executes a ForEach activity on items defined in the same pipeline's parameter 'source_tables' of type Array.
The default value for this parameter is defined as follows:

[{"source":{"table":"tableA"},"destination":{"fileName":"tableA.parquet","datasetName":"tableA"}},  
 {"source":{"table":"tableB"},"destination":{"fileName":"tableB.parquet","datasetName":"tableB"}},  
  *other items...*   
]  

The pipeline works well when run by itself.
What I'm trying to do is to reuse this pipeline in another pipeline with an Execute Pipeline activity.
When I drag and drop the existing pipeline (child) into the new pipeline (parent), I can see that the default value for the 'source_tables' parameter of the child pipeline is well reflected and visible from the parent pipeline when I click on the Execute Pipeline activity.
However, when I execute the parent pipeline, it fails with a message:

Operation on target ForEach_xxx failed: The execution of template action 'MainForEach_xxx' failed: the result of the evaluation of 'foreach' expression '@pipeline().parameters.source_tables' is of type 'String'. The result must be a valid array.  

'@pipeline().parameters.source_tables' is the dynamic expression I use in the ForEach activity of the child pipeline to retrieve the value of the parameter of the child pipeline.
Again, the child pipeline works well on its own, but when it is called from another pipeline the Array somehow becomes a string...

Answer 1

Hi @ThierryL-3166 ,
Thankyou for using Microsoft Q&A platform and posting your query.
Let me summarize your issue , you are using execute pipeline activity to run the child pipeline having pipeline parameters with some default values. When you are executing the master pipeline, you are expecting the child pipeline should run with the default values provided. Please let me know if my understanding is not correct.

You need to pass the parameter value from the master pipeline. As the default value is set for child pipeline , however , as you are calling it from master pipeline you need to provide the values from master pipeline itself. Kindly try creating the parameter in master pipeline with the same value and call that pipeline parameter inside the source_tables value using dynamic content.

Here is the video for your reference:

Please refer to following video for more details : https://www.youtube.com/watch?v=nc4IFKkkfXM&t=35s

Hope this will help. Please let us know if any further queries.

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Answer 2

I faced the same problem but the above accepted solution didn't work for me.

I edited the JSON code and put the array in the way it's mentioned in the below link

Answer 3

I faced the same problem but the above accepted solution didn't work for me.

I edited the Json code and put the array in the way it's mentioned in the below link .

Answer 4

I, too, am using a nested loop setup. My outer pipeline has a ForEach loop that iterates over the first array. Inside, it calls the inner pipeline and passes it a second array as a parameter. The inner pipeline has a second ForEach task that iterates over the second array. In both the outer and inner pipelines, the parameter is defined as an array. And the inner pipeline fails. My solution was to change the parameter type on the outer pipeline from array to string. I guess an array type parameter cannot accept an array as input, go figure. But it CAN accept a string input.