DynamoDB UpdateItem error: Two document paths overlap with each other

[cln-m4rie]

Reporting Bugs

Moto Version: 3.1.15.dev7

The following error occurred in DynamoDB on AWS, but passed in Moto.

An error occurred (ValidationException) when calling the UpdateItem operation: Invalid UpdateExpression: 
Two document paths overlap with each other; 
must remove or rewrite one of these paths; 
path one: [column_name], path two: [column_name]

[bblommers]

Hi @cln-m4rie, thanks for raising this.

Can you share a reproducible test case that showcases this error?

[cln-m4rie]

@bblommers

This way

import boto3
from moto import mock_dynamodb2


def run():
    mock_dynamodb = mock_dynamodb2()
    mock_dynamodb.start()
    dynamodb = boto3.resource("dynamodb")
    dynamodb.create_table(
        TableName="example_table",
        KeySchema=[{"AttributeName": "id", "KeyType": "HASH"}],
        AttributeDefinitions=[
            {"AttributeName": "id", "AttributeType": "S"},
        ],
        BillingMode="PAY_PER_REQUEST",
    )
    record = {
        "id": "example_id",
        "example_column": "example",
    }
    table = dynamodb.Table("example_table")
    table.put_item(Item=record)
    updated = table.update_item(
        Key={"id": "example_id"},
        UpdateExpression="set example_column = :example_column, example_column = :example_column",
        ExpressionAttributeValues={":example_column": "test"},
        ReturnValues="ALL_NEW",
    )
    print(updated)
    mock_dynamodb.stop()


run()