Ambiguity in loop variable #item when using contains within reduce in Data Flow Expressions.

Question

Ambiguity in loop variable #item when using contains within reduce in Data Flow Expressions.

Sathyajit Loganathan 0

I am trying to use a contains function within a reduce function. If I were to perform some comparison on the two items how would I accomplish this?

Would the #item loop variable within the contain override the #item loop variable in the reduce function?

Example use-case:

reduce(
	split($disallowedCharacters, ''),
	false(),
	#acc || contains(split(fieldName, ''), #itemFromReduce != #itemFromContain),
	#result
)

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Your answer

Answer 1

Amira Bedhiafi 29,711

You need to explicitly differentiate between the loop variables in the outer and inner scopes. Unfortunately, ADF Data Flow Expressions do not support renaming loop variables directly. However, you can work around this limitation by using intermediate variables or restructuring your logic.

Use an intermediate variable to store the #item from the reduce function.
Use a different variable name for the inner contains function.


reduce(

    split($disallowedCharacters, ''),

    false(),

    #acc || contains(

        split(fieldName, ''),

        #itemFromReduce != #itemFromContain

    ),

    #result

)

If you cannot rename the loop variables, you can use intermediate variables to store the values temporarily:


reduce(

    split($disallowedCharacters, ''),

    false(),

    #acc || (

        #tempItemFromReduce = #item,

        contains(

            split(fieldName, ''),

            #tempItemFromReduce != #item

        )

    ),

    #result

)

Sathyajit Loganathan 0 Reputation points

2025-03-13T10:06:40.4233333+00:00

Thanks a lot for your response @Amira Bedhiafi

I have provided some screenshots of using intermediate variables as suggested by you. It seems to be erroneous.

When searching up for intermediate variables I couldn't find any relevant results either.
Would you be able to provide some reference documentation about intermediate variables in data flow expressions for your suggested usage in your response?

Without intermediate variable:

With intermediate variable:

Error Message:

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Ambiguity in loop variable #item when using contains within reduce in Data Flow Expressions.

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