Daily DAX : DAy 373 CUSTOMDATA

Power BI DAX CUSTOMDATA Function

Description

The CUSTOMDATA function in Power BI DAX retrieves the value of the CustomData property from the connection string used to connect to the data source. It is primarily used in scenarios where dynamic data access or user-specific filtering is required based on connection metadata.

Syntax

CUSTOMDATA()

• No parameters: The function does not accept any arguments.
• Return value: Returns a string containing the value of the CustomData property from the connection string, or an empty string if not defined.

Use Case

The CUSTOMDATA function is commonly used in role-based security or dynamic data filtering. For example, it can be used to filter data based on user-specific information passed through the connection string, such as a user ID, department, or region.

Example

Suppose a Power BI report is connected to a data source with a connection string that includes a CustomData property like UserID=12345. You can use CUSTOMDATA to filter data for that specific user.

FilteredTable = 
    FILTER(
        Sales,
        Sales[UserID] = CUSTOMDATA()
    )

In this example, the FilteredTable measure returns only the rows from the Sales table where the UserID matches the CustomData value (e.g., "12345").

Common Scenarios

• Row-Level Security (RLS): Use CUSTOMDATA to apply security filters dynamically based on user-specific data in the connection string.
• Multi-Tenant Applications: Filter data for different clients or tenants based on tenant-specific identifiers in the CustomData property.
• Dynamic Reporting: Customize report data based on metadata passed through the connection string, such as region or department.

Limitations

• Only works if the CustomData property is explicitly defined in the connection string.
• Not supported in all data sources; primarily used with Analysis Services or Power BI Embedded.
• Returns an empty string if no CustomData property is set.

Notes

CUSTOMDATA is particularly useful in Power BI Embedded or Azure Analysis Services scenarios where the connection string can be dynamically modified to include user-specific metadata. Ensure the data source supports CustomData and that the property is correctly configured.