AppSync DynamoDB resolver for filtering use case

1
votes

I am working on an app which allows users to upload resources to the internet.

I'm struggling with how to write a resolver for fetching resources posted by a specific user.

I have 3 DynamoDB tables

  • UserTable -> a collection for user
  • PostTable -> a collection for resources
  • PostUserTable -> a collection for storing relations between User and Post

In a traditional RDBS, it would be done by joining 2 tables(UserTable and PostTable) using PostUserTable. Even though DynamoDB, or any kinds of NoSQL database allows us to have a more flexible way to store data, I expect(hope) each user has many resources at the end of the day, so I decided to design tables in the same way as RDMS.

But I'm not sure how you can write a resolver for filtering posts only by a specific user? I have a graphql query named getMyPosts and I want it to return posts uploaded by me.

1
amazon-dynamodbgraphqlaws-appsync

1 Answers

1
votes

If you go to the AppSync console and click "Attach" on a field to add a resolver, there is a drop down in the top right of each resolver template code editor that has a number of commented examples of how to craft resolver templates for DynamoDB. This is a good place to start and has multiple examples of filters and more. You can read more about the full DynamoDB filter syntax here: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Query.html#Query.FilterExpression.