topic Re: Using Helper Functions in User Data Functions in Data Engineering

Using Helper Functions in User Data Functions

cgroleau — Thu, 29 May 2025 20:54:32 GMT

According to the Fabric documentation, in data functions, a published function with the

@udf.function()

decorator, should be able to call a function that does not have the decorator as a helper function. In practice, I have not been able to get this to work in any shape or form and I get the same error.

Sample code:

import fabric.functions as fn udf = fn.UserDataFunctions() def helper_function() -> str: return "Text from helper function" @udf.function() def call_another_function() -> str: return helper_function()

Error:

{ "functionName": "call_another_function", "invocationId": "00000000-0000-0000-0000-000000000000", "status": "Failed", "errors": [ { "errorCode": "WorkloadException", "subErrorCode": "NotFound", "message": "User data function: 'call_another_function' invocation failed." } ] }

Re: Using Helper Functions in User Data Functions

v-prasare — Fri, 30 May 2025 12:27:25 GMT

Hi @cgroleau,

we are looking into it

Thanks,

Prashanth Are

MS Fabric community support

Re: Using Helper Functions in User Data Functions

cgroleau — Fri, 30 May 2025 13:43:00 GMT

Found the issue, and it was my error. In my other testing I had declared another function and made an error in the decorator. I forgot to add the open and close brackets on `udf.function`. This had the odd behavior of still allowing all functions to publish, but none of them could be found when trying to run them.

Re: Using Helper Functions in User Data Functions

v-prasare — Mon, 02 Jun 2025 07:32:39 GMT

Hi @cgroleau,

Thanks for actively participating in MS Fabric community support.

Great to hear you found the root cause of the issue! Thank you for sharing the details.

If this resolves your issue, please consider marking your post as accept as solution. Doing so helps other community members who run into similar problems find the solution more easily.

Thanks,

Prashanth Are