Function.IsDataSource

Function

Returns whether or not a function is considered a data source.

Syntax

Function.IsDataSource(function as function) as logical

Parameters

Name	Type	Required	Description
`function`	`function`	Yes	The function to check for data source status.

Return Value

logical — True if the function is considered a data source, false otherwise.

Remarks

Function.IsDataSource returns true if the provided function is considered a data source function by the Power Query engine, and false otherwise. Data source functions are functions that connect to external data — such as Sql.Database, Web.Contents, Excel.Workbook, OData.Feed, etc.

The Power Query engine treats data source functions specially for:

Credential management — data source functions trigger credential prompts and have their credentials managed by the engine.
Privacy levels — data source functions are subject to data privacy firewall rules.
Query folding — the engine knows to attempt query folding against data source functions.
Refresh behavior — data source functions determine when and how data is refreshed.

This function is useful in advanced scenarios such as:

Custom connector development to verify that a function has been properly registered as a data source.
Diagnostic or introspection utilities that analyze the functions used in a query.

User-defined functions created with let or (x) => ... syntax will return false.

Examples

Example 1: Check built-in functions for data source status

let
    IsDS_SqlDb = Function.IsDataSource(Sql.Database),
    IsDS_TextUpper = Function.IsDataSource(Text.Upper)
in
    #table(
        {"Function", "IsDataSource"},
        {
            {"Sql.Database", IsDS_SqlDb},
            {"Text.Upper", IsDS_TextUpper}
        }
    )

Output

	Function	IsDataSource
1	Sql.Database	TRUE
2	Text.Upper	FALSE

Compatibility

✓ Power BI Desktop✓ Power BI Service✓ Excel Desktop✓ Excel Online✓ Dataflows✓ Fabric Notebooks