UDF User Data Function - error when user has not access to function

[SnoekLaurens]

I have created some UDF functions for writeback to Fabric warehouse from a Power BI report. This is working as expected.

Only thing that I'm not able to manage is an error message of some kind when someone presses the button that triggers the data function but isn't authorized for that function (new object in Fabric). Nothing happens but the user isn't made aware that nothing has happend and that he is not authorized to run use the function. It would be helpfull if that could be added somehow.

I initially tried to add the error message to the python of the UDF itself but that doesn't help as the UDF is never started in this case.

Has anyone a solution for this?

[Nasif_Azam]

Hey @SnoekLaurens ,

To handle the situation where a user is not authorized to run the UDF (User Data Function) in your Power BI report, and ensure they receive a proper error message. Solution you can try:

1. Check User Permissions Before Triggering the UDF: Before executing the UDF, you can check whether the user has the necessary permissions to access or trigger the function. This can be done in Power BI or within the Power Query/Power Automate flow.

2. Use Power Automate for Authorization Check:Create a flow to check user permissions before calling the UDF. If the user lacks access, the flow can send a notification or show an error message.

   Example:

   • Create a Power Automate flow that gets triggered by the button click.

   • Before calling the UDF, add a step that checks the user's permissions.

   • If the permissions check fails, the flow can terminate and send an email, show a notification, or trigger a message in the Power BI report.

3. Error Handling in Power BI: Since you can't add error handling directly to the UDF if the function is never triggered, consider using DAX or Power Query to check if the user is authorized before showing any writeback options. You can show a custom message or disable the button depending on the user’s role or access level.

   For instance, in DAX:

   IF(HasUserPermission() = FALSE(), "You do not have permission to perform this action", "Writeback to Fabric Warehouse")

   This approach provides visual feedback within the report before the user presses the button.

4. Feedback in the User Interface (UI): If the UDF is being triggered via Power BI's custom visuals or buttons, make sure that the UI is providing proper feedback to users about their access rights. You can design the button to display an error message (or disable the button) when the user doesn’t have access, using a combination of DAX and Power Automate.

For Detailed Information:

Power BI Error Handling

Using Power Automate to Check User Permissions

Power BI Button Action with Error Message

Azure Role-Based Access Control (RBAC) for Power BI

Power BI DAX Functions for Error Handling

If you found this solution helpful, please consider accepting it and giving it a kudos (Like) it’s greatly appreciated and helps others find the solution more easily.

Best Regards,
Nasif Azam

[SnoekLaurens]

I'm using the new native writeback capability with the new UDF function in Microsoft Fabric so I'm not using Power Automate and also Power Query is not directly used for this purpose.

So option 3 seems suitable but I have no idea how to do that in Power BI. I have a button with the data function connected. How can I add this to that button?

[Nasif_Azam]

Hey @SnoekLaurens ,

Since you're using the new native writeback functionality in Microsoft Fabric with UDF and not using Power Automate or Power Query, the solution should focus on enhancing the button’s behavior directly in Power BI. Steps to Add Error Handling to the Button:

1. Create a DAX Measure for User Permissions: First, create a DAX measure that checks whether the current user has the necessary permissions. This could be based on roles or a user table that tracks access levels.

   UserHasPermission = 
   IF(
       CONTAINS(
           UserPermissions[UserID], 
           UserPermissions[UserID], USERNAME()
       ), 
       TRUE, 
       FALSE
   )

2. Set the Button Action Based on the Permission Check:

   • You can use the UserHasPermission measure in the button’s Action property to control whether the UDF is triggered.

   • If the user does not have permission, you can set the button action to None or show a message indicating lack of access.

3. Use a Dynamic Tooltip/Message: You can also configure the button’s tooltip or dynamic text to inform the user about their permission status.

   ButtonMessage = 
   IF(
       [UserHasPermission] = TRUE(),
       "Click to writeback to Fabric Warehouse",
       "You do not have permission to perform this action"
   )

4. Provide Feedback on the Button: Set the Visible property of the button based on the permission measure:

   ButtonVisible = 
   IF([UserHasPermission] = TRUE(), TRUE(), FALSE())

   This way, the button can either be visible or hidden depending on the user's access level.

Implement these DAX measures in your Power BI report and link them to the button properties like Action, Visible, and Tooltip to manage user interactions based on their permissions.

If you found this solution helpful, please consider accepting it and giving it a kudos (Like) it’s greatly appreciated and helps others find the solution more easily.

Best Regards,
Nasif Azam