Cannot read property 'type' of undefined on building with union result type

[ashkart]

I have an error when working with union result type.
Here is working demo
Uncomment getUserWithUnion method in resolver.ts to reproduce the problem.

TypeError: Cannot read property 'type' of undefined
    at /home/maxim/workspace/demo/node_modules/type-graphql/dist/schema/schema-generator.js:66:101
    at Array.map (<anonymous>)
    at types (/home/maxim/workspace/demo/node_modules/type-graphql/dist/schema/schema-generator.js:66:22)
    at resolveThunk (/home/maxim/workspace/demo/node_modules/graphql/type/definition.js:438:40)
    at defineTypes (/home/maxim/workspace/demo/node_modules/graphql/type/definition.js:837:15)
    at GraphQLUnionType.getTypes (/home/maxim/workspace/demo/node_modules/graphql/type/definition.js:806:26)
    at typeMapReducer (/home/maxim/workspace/demo/node_modules/graphql/type/schema.js:272:28)
    at typeMapReducer (/home/maxim/workspace/demo/node_modules/graphql/type/schema.js:286:20)
    at Array.reduce (<anonymous>)
    at new GraphQLSchema (/home/maxim/workspace/demo/node_modules/graphql/type/schema.js:145:28)

[MichalLytek]

@ashkart Why UserNotFoundProblem has no decorators applied?

[ashkart]

Because i created it through createUnionType method. I didnt find any decorator for this case.
Should i use any of them? Which one?

[MichalLytek]

https://typegraphql.ml/docs/unions.html

types: () => [Movie, Actor], // function that returns array of object types classes

As stated per GraphQL specification, union type can consist only object types:
http://graphql.org/learn/schema/#union-types

[ashkart]

Confirmed, this is my bad, just got some misunderstanding with different graphql union types guides.

[aounleonardo]

Hey @MichalLytek , would it be possible to have a clearer error message and stacktrace when the schema build fails? I frequently run into this problem and it takes time to find the change that caused it :/
I'll try to look into it myself too, but I doubt that I have enough knowledge about the library :/

[MichalLytek]

@aounleonardo Do you use the latest 1.0.0-rc.1?

[aounleonardo]

Thanks @MichalLytek for the quick reply 😲

No I'm still on: "type-graphql": "^0.17.6",
But I digged into the dist files and the error comes in the graphql GraphQLSchema constructor, so I need to look into the core code, or we could add more verifiers before we even call the constructor.

[MichalLytek]

No I'm still on: "type-graphql": "^0.17.6",

So please update and check because the error messages are not much more improved.

[aounleonardo]

@MichalLytek Good to know, thanks! I upgraded but the messages are still not that helpful, though I guess the problem is still coming from the graphql library side.
Here are my packages:

ubuntu@host:~/backend$ cat package.json | grep graphql
    "@types/graphql-relay": "^0.6.0",
    "express-graphql": "^0.9.0",
    "graphql": "15.0.0",
    "graphql-relay": "^0.6.0",
    "type-graphql": "1.0.0-rc.1",
    "@types/graphql": "^14.5.0",

And here's the error message, it would be helpful if they could log the name of the class causing that error.

$ ts-node-dev --respawn src/index.ts
Using ts-node version 8.8.2, typescript version 3.8.3
{
  err: TypeError: Cannot read property 'name' of undefined
      at /home/ubuntu/backend/node_modules/type-graphql/dist/schema/schema-generator.js:130:114
      at Array.map (<anonymous>)
      at interfaces (/home/ubuntu/backend/node_modules/type-graphql/dist/schema/schema-generator.js:127:59)
      at resolveThunk (/home/ubuntu/backend/node_modules/graphql/type/definition.js:468:40)
      at defineInterfaces (/home/ubuntu/backend/node_modules/graphql/type/definition.js:661:37)
      at GraphQLObjectType.getInterfaces (/home/ubuntu/backend/node_modules/graphql/type/definition.js:621:31)
      at collectReferencedTypes (/home/ubuntu/backend/node_modules/graphql/type/schema.js:361:61)
      at new GraphQLSchema (/home/ubuntu/backend/node_modules/graphql/type/schema.js:148:9)
      at Function.generateFromMetadataSync (/home/ubuntu/backend/node_modules/type-graphql/dist/schema/schema-generator
.js:30:24)
      at Function.generateFromMetadata (/home/ubuntu/backend/node_modules/type-graphql/dist/schema/schema-generator.js:
15:29)
}

[aounleonardo]

Oh actually maybe I spoke too quickly, the error comes from the callback called by their constructor...