Fn::Length

The intrinsic function Fn::Length returns the number of elements within an array or an intrinsic function that returns an array.

Important

You must use the AWS::LanguageExtensions transform to use the Fn::Length intrinsic function.

Declaration

JSON

{ "Fn::Length" : IntrinsicFunction }

{ "Fn::Length" : Array }

YAML

Fn::Length : IntrinsicFunction

Fn::Length : Array

Parameters

IntrinsicFunction

The intrinsic function that returns an array that you want to return a number of elements from.

Array

The array you want to return the number of elements from.

Return value

The number of elements in the intrinsic function that returns an array or in the array passed to the intrinsic function.

Examples

Return the number of elements in an intrinsic function that returns an array

This example snippet returns the number of elements in an intrinsic function that returns an array. The function returns 3.

JSON

{
//...
    "Transform": "AWS::LanguageExtensions"
    //...
        "Fn::Length" : {
            "Fn::Split": ["|", "a|b|c"]
        }
//...
}

YAML

Transform: 'AWS::LanguageExtensions'
#...
  Fn::Length: 
    !Split ["|", "a|b|c"]
#...

Return the number of elements in a Ref intrinsic function that refers to a list parameter type

This example snippet returns the number of elements in a Ref intrinsic function that refers to a list parameter type. If the parameter with the name ListParameter is a list with 3 elements, the function returns 3.

JSON

{
//...
    "Transform": "AWS::LanguageExtensions"
    //...
        "Fn::Length": {
            "Ref": "ListParameter"
        }
//...
}

YAML

Transform: 'AWS::LanguageExtensions'
#...
  Fn::Length: 
    !Ref ListParameter
#...

Return the number of elements in an array

This example snippet returns the number of elements in the array passed to the intrinsic function. The function returns 3.

JSON

{
//...
    "Transform": "AWS::LanguageExtensions"
    //...
        "Fn::Length": [
            1,
            {"Ref": "ParameterName"}, 
            3
        ]
//...
}

YAML

Transform: 'AWS::LanguageExtensions'
#...
  Fn::Length: 
    - 1
    - !Ref ParameterName
    - 3
#...

Supported functions

You can use the following functions in the Fn::Length intrinsic function or array:

• Condition Functions

• Fn::Base64

• Fn::FindInMap

• Fn::Join

• Fn::Length

• Fn::Select

• Fn::Split

• Fn::Sub

• Fn::ToJsonString

• Ref