👀 Views: 76 💬 Answers: 1 📅 Created: 2025-07-15

aws appsync dynamodb graphql

I'm experiencing an scenario with AWS AppSync where my GraphQL queries are not resolving nested fields from a DynamoDB DataSource correctly. I've defined a GraphQL schema that includes a type with nested objects: ```graphql type User { id: ID! name: String! posts: [Post] } type Post { id: ID! title: String! content: String! } type Query { getUser(id: ID!): User } ``` My DynamoDB table structure looks like this: - Users table with primary key `id` - Each user item has a list of post IDs stored in a `posts` attribute. - I have another Posts table indexed by `id`. In my resolver for the `getUser` query, I’m using the following mapping template to fetch the user: ```json { "version": "2018-05-29", "operation": "GetItem", "key": { "id": $util.dynamodb.toDynamoDBJson($ctx.args.id) } } ``` I also defined a resolver for the `posts` field within the User type: ```json { "version": "2018-05-29", "operation": "BatchGetItem", "tables": { "Posts": { "keys": $util.toJson($ctx.source.posts) } } } ``` When I run the query: ```graphql query { getUser(id: "123") { id name posts { id title } } } ``` I get the following behavior: ``` "behavior": "User posts field want to resolve to the list of posts" ``` It's frustrating because the `posts` attribute exists and it's an array of IDs. I've tried using the AppSync console to test the resolvers independently, and both resolvers seem to return the expected results when tested in isolation. I've also checked the IAM roles and permissions to ensure that AppSync can access both DynamoDB tables. I’m using AWS AppSync with GraphQL and Node.js for the backend. What might be causing this scenario with resolving nested fields, and how can I ensure that my nested posts are fetched correctly? I'm using Graphql latest in this project. Is there a better approach?