Dynalite does not throws if path token starts with underscore #147
Description
Summary
DynamoDB and DynamoDB-local throws ValidationException if attribute name inConditionExpression starts with _.
However, Dynalite does not throw and PutItem succeed.
Expectation
Dynalite should throw, so users can identity invalid chars and escape them using ExpressionAttributeNames.
Repro
DynamoDB Local
docker run -d -p 8000:8000 amazon/dynamodb-local
aws dynamodb create-table \
--endpoint http://localhost:8000 \
--table-name MusicCollection \
--attribute-definitions AttributeName=Artist,AttributeType=S AttributeName=SongTitle,AttributeType=S \
--key-schema AttributeName=Artist,KeyType=HASH AttributeName=SongTitle,KeyType=RANGE \
--provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5
aws dynamodb put-item --endpoint http://localhost:8000 --table-name MusicCollection \
--item '{"Artist": {"S": "Foo"}, "SongTitle": {"S": "Bar"}, "__typename": {"S": "SongItem"}}' \
--condition-expression "__typename <> :__typename" \
--expression-attribute-values '{":__typename":{"S":"SongItem"}}'
This wil throwAn error occurred (ValidationException) when calling the PutItem operation: Invalid ConditionExpression: Syntax error; token: "_", near: "__".
Dynalite
docker run -d -p 8000:8000 dimaqq/dynalite:latest
aws dynamodb create-table \
--endpoint http://localhost:8000 \
--table-name MusicCollection \
--attribute-definitions AttributeName=Artist,AttributeType=S AttributeName=SongTitle,AttributeType=S \
--key-schema AttributeName=Artist,KeyType=HASH AttributeName=SongTitle,KeyType=RANGE \
--provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5
aws dynamodb put-item --endpoint http://localhost:8000 --table-name MusicCollection \
--item '{"Artist": {"S": "Foo"}, "SongTitle": {"S": "Bar"}, "__typename": {"S": "SongItem"}}' \
--condition-expression "__typename <> :__typename" \
--expression-attribute-values '{":__typename":{"S":"SongItem"}}'
This will succeed, but it should fail.