TypeResolver of GraphQL interface type is not working

[daveekr]

Issue workflow progress

Progress of the issue based on the Contributor Workflow

• 1. The issue provides a reproduction available on Github, Stackblitz or CodeSandbox

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Please make sure Mesh package versions under package.json matches yours.

• 2. A failing test has been provided
• 3. A local solution has been provided
• 4. A pull request is pending review

---

Describe the bug
The type of an object implementing an interface cannot be resolved, although a resolver has been defined and added to the .meshrc.yaml. Mesh then quits with an error from graphql-jit/execution.ts stating Could not resolve the object type in possible types of Fruit for the value: {"name":"Apple","type":"tree"}, which is because Fruit.resolveType is undefined, so for some reason the defined TypeResolver is not applied.

To Reproduce
Steps to reproduce the behavior:
I have an OpenAPI schema returning an array of abstract objects (Fruit). Mesh generates:

Fruits {
  fruits: [JSON]
}

So Mesh is not capable of producing a proper schema for abstract return types. However I then tried to replace the field Fruits.fruit with a proper representation (.meshrc.yaml).

      - replaceField:
          typeDefs: |
              interface Fruit {
                name: String!
              }

              type FruitsInt {
                fruits: [Fruit]
              }

              type Apple implements Fruit {
                 name: String!
                 type: String
              }
          replacements:
            - from:
                type: Fruits
                field: fruits
              to:
                type: FruitsInt
                field: fruits

I also added an additional resolver resolvers.ts to resolve the type of Fruit.

import { Resolvers } from "./.mesh";

const resolvers: Resolvers = {
  Fruit: {
    __resolveType: (obj, context, info) => {
      return "Apple";
    },
  },
  Apple: {
    __isTypeOf: (event) => true,
  },
};

export default resolvers;

Expected behavior
The defined resolver is being applied properly to the GraphQLInterfaceType instance and consequently the type resolution works as intended.

Environment:

• OS: macOSX 12.3.1
• @graphql-mesh/cli: "^0.68.3"
• @graphql-mesh/json-schema: "^0.28.3"
• @graphql-mesh/openapi: "^0.24.13"
• @graphql-mesh/transform-replace-field: "0.3.46"
• graphql: "^16.3.0"
• NodeJS: v17.9.0

[daveekr]

@charlypoly we already had a conversation about this issue.

[paradigm314]

I believe this is the same issue here: #2382 opened back in June of last year.

[charlypoly]

Hi @g0rill4z,

Thank you for your explanation!

In order to better understand the issue, could you provide a working reproduction on Github, Stackblitz or CodeSandbox?

Thank you!

[ardatan]

GraphQL JIT is not used anymore so this doesn't seem to be an issue. Let us know if the issue persists so we can reopen the issue.