ADF ForEach Activity

This occasional series of posts I'm calling Notes from the field is primarily for my benefit as I don't work with Azure Data Factory with any regularity and have no muscle memory in it. And the amount of sharp edges and non-intuitive baked in the product is quite frustrating for me. If you derive value from it, all the better.

The Azure Data Factory ForEach Activity shreds some enumerable thing but here I want to reference a Lookup to ForEach.

When I click on the ForEach Activity, in the "Items" section. I click "Add dynamic content" and am presented with these wonderful choices (given that my canvas consists of a Lookup Activity named "LKP_ReferenceTables" and the ForEach wired as a successor:

My options are

LKP_ReferenceTables

LKP_ReferenceTables activity output

LKP_ReferenceTables

LKP_ReferenceTables pipeline return value

LKP_ReferenceTables count

Count of the rows

LKP_ReferenceTables value array

Array of row data

and if I pick "activity output" the dyanmic expression is @activity('LKP_ReferenceTables').output WILLIAM! DO NOT CLICK OK, yet. If you accept the default code, you're going to get a lovely error in the form of Operation on target FE_ReferenceTables failed: The function 'length' expects its parameter to be an array or a string. The provided value is of type 'Object' You need to add the ".value" property to the expression to get the actual stuff you want @activity('LKP_ReferenceTables').output.value

Orrrr, I pick Array of row data and that generates the expected @activity('LKP_ReferenceTables').output.value Le sigh