CognitoIdentityProvider / Client / add_custom_attributes



Adds additional user attributes to the user pool schema.


Amazon Cognito evaluates Identity and Access Management (IAM) policies in requests for this API operation. For this operation, you must use IAM credentials to authorize requests, and you must grant yourself the corresponding IAM permission in a policy.

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See also: AWS API Documentation

Request Syntax

response = client.add_custom_attributes(
            'Name': 'string',
            'AttributeDataType': 'String'|'Number'|'DateTime'|'Boolean',
            'DeveloperOnlyAttribute': True|False,
            'Mutable': True|False,
            'Required': True|False,
            'NumberAttributeConstraints': {
                'MinValue': 'string',
                'MaxValue': 'string'
            'StringAttributeConstraints': {
                'MinLength': 'string',
                'MaxLength': 'string'
  • UserPoolId (string) –


    The user pool ID for the user pool where you want to add custom attributes.

  • CustomAttributes (list) –


    An array of custom attributes, such as Mutable and Name.

    • (dict) –

      A list of the user attributes and their properties in your user pool. The attribute schema contains standard attributes, custom attributes with a custom: prefix, and developer attributes with a dev: prefix. For more information, see User pool attributes.

      Developer-only attributes are a legacy feature of user pools, are read-only to all app clients. You can create and update developer-only attributes only with IAM-authenticated API operations. Use app client read/write permissions instead.

      • Name (string) –

        The name of your user pool attribute. When you create or update a user pool, adding a schema attribute creates a custom or developer-only attribute. When you add an attribute with a Name value of MyAttribute, Amazon Cognito creates the custom attribute custom:MyAttribute. When DeveloperOnlyAttribute is true, Amazon Cognito creates your attribute as dev:MyAttribute. In an operation that describes a user pool, Amazon Cognito returns this value as value for standard attributes, custom:value for custom attributes, and dev:value for developer-only attributes..

      • AttributeDataType (string) –

        The data format of the values for your attribute. When you choose an AttributeDataType, Amazon Cognito validates the input against the data type. A custom attribute value in your user’s ID token is always a string, for example "custom:isMember" : "true" or "custom:YearsAsMember" : "12".

      • DeveloperOnlyAttribute (boolean) –


        You should use WriteAttributes in the user pool client to control how attributes can be mutated for new use cases instead of using DeveloperOnlyAttribute.

        Specifies whether the attribute type is developer only. This attribute can only be modified by an administrator. Users won’t be able to modify this attribute using their access token. For example, DeveloperOnlyAttribute can be modified using AdminUpdateUserAttributes but can’t be updated using UpdateUserAttributes.

      • Mutable (boolean) –

        Specifies whether the value of the attribute can be changed.

        Any user pool attribute whose value you map from an IdP attribute must be mutable, with a parameter value of true. Amazon Cognito updates mapped attributes when users sign in to your application through an IdP. If an attribute is immutable, Amazon Cognito throws an error when it attempts to update the attribute. For more information, see Specifying Identity Provider Attribute Mappings for Your User Pool.

      • Required (boolean) –

        Specifies whether a user pool attribute is required. If the attribute is required and the user doesn’t provide a value, registration or sign-in will fail.

      • NumberAttributeConstraints (dict) –

        Specifies the constraints for an attribute of the number type.

        • MinValue (string) –

          The minimum value of an attribute that is of the number data type.

        • MaxValue (string) –

          The maximum length of a number attribute value. Must be a number less than or equal to 2^1023, represented as a string with a length of 131072 characters or fewer.

      • StringAttributeConstraints (dict) –

        Specifies the constraints for an attribute of the string type.

        • MinLength (string) –

          The minimum length.

        • MaxLength (string) –

          The maximum length of a string attribute value. Must be a number less than or equal to 2^1023, represented as a string with a length of 131072 characters or fewer.

Return type:



Response Syntax


Response Structure

  • (dict) –

    Represents the response from the server for the request to add custom attributes.


  • CognitoIdentityProvider.Client.exceptions.ResourceNotFoundException

  • CognitoIdentityProvider.Client.exceptions.InvalidParameterException

  • CognitoIdentityProvider.Client.exceptions.TooManyRequestsException

  • CognitoIdentityProvider.Client.exceptions.NotAuthorizedException

  • CognitoIdentityProvider.Client.exceptions.UserImportInProgressException

  • CognitoIdentityProvider.Client.exceptions.InternalErrorException