Mock: Cannot return null for non-nullable field [Object.id]

[kldeb]

Describe the bug
When running amplify mock there are connections that are not required that are causing the following error to appear when I run the queries, for example:

Cannot return null for non-nullable field Utility.id.

The id field on the connected object is non-nullable but the object itself is nullable. This works fine when querying AppSync.

Here's the relevant snippet from my schema:

type Utility
  @model
{
  id: ID!
  name: String!
}

type Account
  @model
{
  id: ID!
  [...]
  utility: Utility @connection
[...]
}

The mutation to create the record:

mutation CreateAccount {
  createAccount(input: {
    id: "e4b91a75-7843-442d-aab9-e94bc81c4cb7",
  }) {
    id
    utility {
      id
    }
  }
}

The query that will produce the error:

query GetAccount {
  getAccount(id: "e4b91a75-7843-442d-aab9-e94bc81c4cb7") {
    id
    utility {
      id
    }
  }
}

To Reproduce
Steps to reproduce the behavior:

1. Create a schema with a connection that is nullable
2. Run amplify mock
3. Create a record without that field set so the connected object is null
4. Query that field
5. See error

Expected behavior
Show null in query results like AppSync.

Desktop (please complete the following information):

• OS: macOS
• Browser Firfox
• Version Amplify 3.0.0

[jbertman]

Was there a regression that happened to reintroduce this bug? I am currently experiencing this with the following schema:

type Policy
@model(queries: { get: "getPolicy", list: "listPolicies" })
@auth(
    rules: [
        { allow: owner }
        { allow: groups, groups: ["Admin"] }
        { allow: private, provider: iam, operations: [read] }
    ]
) {
    id: ID!
    <SNIP>
    # This is broken in amplify mock
    credential: Credential @connection
}

type Credential
@model
@auth(
  rules: [
    { allow: owner }
    { allow: groups, groups: ["Admin"] }
    { allow: private, provider: iam, operations: [read] }
  ]
) {
  id: ID!
  <SNIP>
  name: String!
}

When pushed, the mutation for createPolicy works without issue (on AppSync). But with amplify mock I get Cannot return null for non-nullable field Credential.id. when trying to CRUD a policy that includes the credential field.

[Nxtra]

@kldeb @jbertman Did you manage to work out a solution for this? I think I ran into the same problem: #6450

[kldeb]

@Nxtra I gave up using mock for everything except lambda testing. I hope to use it again when it catches up to the features that my amplify project uses.

[lostcodingsomewhere]

I too am running into this issue -- currently on version 4.43.0

[lostcodingsomewhere]

For anyone running into this issue (on v4.43.0), here's a workaround (pretty hackey but will suffice for now):

replace all of your API.graphql with the following helper:

const graphqlAPI = async (
   options,
   additionalHeaders?: {
      [key: string]: string;
   }
): Promise<any> => {
   try {
      return await API.graphql(options, additionalHeaders);
   } catch (err) {
      const realErrors = err.errors.filter(
         (e) => !e.message.startsWith('Cannot return null for non-nullable')
      );
      if (realErrors.length > 0) {
         console.log(`THROWING GRAPHQL ERROR`);
         throw err;
      } else {
         const realDataResult = { data: err.data };
         return realDataResult;
      }
   }
};

[github-actions]

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