Amplify Auth Field-Level Authorization Example

Example.ts

// From https://docs.amplify.aws/cli/graphql-transformer/auth#field-level-authorization

// The code where this exception is thrown is: https://github.com/aws-amplify/amplify-js/blob/d9aa32837f15f408daba0a0104bb27042b9331da/packages/api-graphql/src/GraphQLAPI.ts#L314

type User @model {
  id: ID!
  username: String
  ssn: String @auth(rules: [{ allow: owner, ownerField: "username" }])
}

// Amplify will automatically generate the query

const getUser = /* GraphQL */ `
  query GetUser($id: ID!) {
    getUser(id: $id) {
      id
      username
      ssn
  }
}
`;

// I'd use this in this way for async requests

import API, { graphqlOperation, GraphQLResult } from "@aws-amplify/api";

const getUserById = async (userId: string): Promise<User | null> => {
  try {
    const response = await API.graphql(graphqlOperation(getUser, { id: userId}));
    
    /** HERE response SHOULD be structured like this:
      {
        data: { getUser: {id, username, ssn} }
      }
      
      Where SSN would be null if you are not the owner.
    */
    
    return e.data.getUser;
  } catch (err) {
    /** Here I would assume there was an error with the query...
    HOWEVER with the auth rule, there is an exception thrown even though the
    data is correct. so I have to do this...*/
    if (err.data && err.data.getUser) {
      return err.data.getUser;
    }
    
    console.log('Error getting the user: ', err);
    
    return null;
  }
};