CUSTOMDATA DAX Function (Information) Volatile

Returns the value of the CustomData connection string property if defined; otherwise, BLANK().



This expression has no parameters.

Return values

Scalar A single string value.

The content of the CustomData property in the connection string.
Blank, if CustomData property was not defined at connection time.


This function is commonly used in implementing expressions for role-based security when an application uses custom authentication.

This function is not supported in calculated tables/columns.

IMPORTANT: there are reported performance issues if CUSTOMDATA is used in DAX expressions of the model, including RLS filters and measures, in case the connection string does not include CustomData argument. When this happens, simply passing a value to CustomData in the connection string eliminates the performance issue.


--  CUSTOMDATA returns the CUSTOMDATA argument provided in the 
--  connection string.
--  It is mainly useful in custom security systems where the
--  caller uses CUSTOMDATA to communicate security parameters
--  to the AS DAX system

Last update: Jul 19, 2024   » Contribute   » Show contributors

Contributors: Alberto Ferrari, Marco Russo, Kenneth Barber

Microsoft documentation:

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Context Transition

This function performs a Context Transition if called in a Row Context. Click to read more.

Row Context

This expression is executed in a Row Context. Click to read more.


Not recommended

The use of this function is not recommended. See Remarks and Related functions for alternatives.

Not recommended

The use of this parameter is not recommended.


This function is deprecated. Jump to the Alternatives section to see the function to use.


A volatile function may return a different result every time you call it, even if you provide the same arguments. Click to read more.


This parameter is deprecated and its use is not recommended.

DirectQuery compatibility

Limitations are placed on DAX expressions allowed in measures and calculated columns.
The state below shows the DirectQuery compatibility of the DAX function.


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