在 TypeGraphQL 中返回联合

Question

所以我有这个代码：

const getAllUsers = ({
  Model, options,
}) => Model.find(options).catch((e) => {
  throw e;
});

@ObjectType({ description: "User model" })
@Entity()
export class UserModel extends BaseEntity {
    ...
}

@ObjectType()
class Error {
  constructor(data: {message: string, code: number}) {
    this.message = data.message;
    this.code = data.code;
  }
  @Field(() => Int)
  code: number;
  @Field(() => String)
  message: string;
}

@ObjectType()
class Success {
  @Field(() => [ UserModel ])
  users: [UserModel];
}

const UserResponseType = createUnionType({
  name: "UserResponseType",
  types: () => [
    Success,
    Error,
  ] as const,
});

@Query(() => [ UserResponseType ])
async getAllUsers(): Promise<typeof UserResponseType> {
  const errors = await Promise.resolve([
    new Error({
      code: 501,
      message: "test",
    }),
  ]);
  const users = await getAllUsers({
    Model: UserModel,
    options: {
      ...
    },
  }).catch((e) => e);
  return {
    errors,
    success: users,
  };
}

我要做的就是返回错误或成功，以便我可以在查询中执行此操作：

query getAllUsers {
  getAllUsers {
    ... on Success {
      user {
        id
        email
      }
    }
    ... on Error {
      code
      message
    }
  }
}

但现在我得到了：

TS2322: Type '{ errors: Error[]; success: any; }' is not assignable to type 'Error | Success'.
Object literal may only specify known properties, and 'errors' does not exist in type 'Error | Success'.

我试图复制（https://typegraphql.com/docs/unions.html#docsNav）[这个例子） 那么如何才能实现上述的查询能力呢？

Answer 1

async getAllUsers()返回的值与声明的返回值Promise<typeof UserResponseType>不匹配，导致TS2322错误。

该函数返回具有errors 和success 属性的对象，但它应该返回Error 或Success 实例。像这样的东西应该可以工作：

import {
  createUnionType,  
  Field,
  Int,
  ObjectType,
  Query,
  Resolver,
} from "type-graphql";

@ObjectType({ description: "User model" })
export class UserModel {
  @Field()
  id: string;
}

@ObjectType()
class Error {
  @Field(() => Int)
  code: number;
  @Field(() => String)
  message: string;
}

@ObjectType()
class Success {
  @Field(() => [UserModel])
  users: UserModel[];
}

const UserResponseType = createUnionType({
  name: "UserResponseType",
  types: () => [Success, Error] as const,
  resolveType: (value) => {
    if ("code" in value) {
      return Error;
    }
    if ("users" in value) {
      return Success;
    }
    return undefined;
  },
});

@Resolver()
export class UserResolver {
  @Query(() => UserResponseType)
  async getAllUsers(): Promise<typeof UserResponseType> {
    const error: Error = {
      code: 501,
      message: "test",
    };
    const success: Success = { users: [{ id: "1" }, { id: "2" }] };
    return success;
  }
}

现在运行以下查询将返回用户的 ID。如果将return success; 更改为return error;，查询将返回错误详细信息。

query getAllUsers {
  getAllUsers {
    ... on Success {
      users {
        id
      }
    }
    ... on Error {
      code
      message
    }
  }
}