Value.As

Value

Asserts that a value is compatible with a specified type, raising an error if not.

Syntax

Value.As(value as any, type as type) as any

Parameters

Name	Type	Required	Description
`value`	`any`	Yes	The value to assert and cast.
`type`	`type`	Yes	The type to assert compatibility with.

Return Value

any — The original value if it is compatible with the specified type. Raises an error otherwise.

Remarks

Value.As returns the value unchanged if it is compatible with the specified type. If the value is not compatible, an error is raised. This is useful as a runtime assertion to ensure data quality and catch type mismatches early in a query pipeline.

Unlike Value.Is which returns a boolean, Value.As either passes through the value or throws an error. Use Value.Is for conditional logic and Value.As for strict enforcement.

Examples

Example 1: Assert Sales UnitPrice values are numbers

let
    Prices = Table.Column(Table.FirstN(Sales, 4), "UnitPrice"),
    Asserted = List.Transform(Prices, each Value.As(_, type number))
in
    #table({"UnitPrice"}, List.Transform(Asserted, each {_}))

Result

	UnitPrice
1	25
2	50
3	15
4	75

Compatibility

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