Type.IsNullable is a Power Query M function that determines if a given type is nullable. The function returns true if the type is nullable and false otherwise.
Compatible with: Power BI Service Power BI Desktop Excel Microsoft 365
Syntax
Type.IsNullable( type as type ) as logical
Description
The Type.IsNullable
function is designed to determine whether a specified data type is nullable, meaning it can accept null values.
It takes a single input: the data type to be assessed, which can range from primitive types like text
or number
to more complex types. The function evaluates whether the provided type inherently allows for null values or has been explicitly declared as nullable using the nullable
keyword. It returns a boolean value, true
if the type is nullable and false
if not.
Examples
Let’s look at a few examples to illustrate how this function works with various data types.
Determining Nullable Status of Text Type
You can use the following expression to test whether the type text
is nullable.
// Output: false
Type.IsNullable( type text )
This demonstrates that the standard text type
cannot accommodate null values, but only supports text.
Transforming Primitive Types to Support Null Values
Any primitive type can, however, transform into a form that supports null values by using the ‘nullable’ keyword. Here’s how:
// Output: true
Type.IsNullable( type nullable text )
This example shows how the ‘nullable’ keyword extends the flexibility of the text type
.
Applying Nullable to the Type Anynonnull
Even a type like anynonnull
, which by definition excludes null values, can be made nullable:
// Output: true
Type.IsNullable( type nullable anynonnull)
This shows the flexibility of the ‘nullable’ keyword in altering data type properties.
Nullable Nature of the Type Any
The any
type, a more encompassing data type, inherently supports null values without requiring the nullable
keyword:
// Output: true
Type.IsNullable( type any )
In fact, the any type
supports any values, so that includes nulls.
Related functions
Other functions related to Type.IsNullable are:
2023-2024 © BI Gorilla. All rights are reserved. Information from Microsoft docs is property of Microsoft Corp. | Privacy Policy