Look for a case to learn from this library

[LeonYanghaha]

This document is too rough, there are many places I can't understand. Who has better code or project, can I look at the code to learn it? Thank you very much.

[yaacovCR]

What are you trying to learn?

What parts in particular here are difficult to understand?

The code in general is sparsely commented. A great way to learn might be to attempt pull requests adding comments, with questions about unclear code. Would be happy to review.

[LeonYanghaha]

Thank you for your answer. I have a lot of questions, the following is the most confusing

• If there are other cases, I look at the code usage, which may help me understand. I have only documents now, so it's hard for me to understand.
• Subschema & Parent schema,What is the relationship between subschema & parent schema? How do they represent it in code? Is it the same serve or two serve?
• This code, when is the bookings function called? Who is calling? How to write other resolver functions? I wrote it according to the general situation, and then I got the error "typeof is not function". This makes me wonder, I don't have typeof function

const resolvers = {
  User: {
    bookings(parent, args, context, info) {
      return delegateToSchema({
        schema: subschema,
        operation: 'query',
        fieldName: 'bookingsByUser',
        args: {
          userId: parent.id,
        },
        context,
        info,
      });
    },
    ...
  },
  ...
};

[yaacovCR]

1. There are some guides available at https://www.graphql-tools.com/
2. Subschemas could be local or remote, but practically most useful for remote subschemas not under control or autogenerated local subschemas, otherwise could just be integrated into parent schema.
3. This question is a general graphql-js question not specific to delegation or remote schemas. See https://www.graphql-tools.com/docs/resolvers and https://graphql.org/learn/execution/#root-fields-resolvers

[LeonYanghaha]

I wrote the code according to this document. But the result was a little inconsistent with my expectation. I didn't understand why "Hello world" appeared? Can you help me see what went wrong? Thank you very much.

I got this result

Here is my code

const {makeExecutableSchema} = require('@graphql-tools/schema');
const {addMocksToSchema} = require('@graphql-tools/mock');
const {stitchSchemas} = require('@graphql-tools/stitch');
const {delegateToSchema} = require('graphql-tools');

let chirpSchema = makeExecutableSchema({
  typeDefs: `
    type Chirp {
      id: ID!
      text: String
      authorId: ID!
    }

    type Query {
      chirpById(id: ID!): Chirp
      chirpsByAuthorId(authorId: ID!): [Chirp]
    }
  `
});

chirpSchema = addMocksToSchema({schema: chirpSchema});

let authorSchema = makeExecutableSchema({
  typeDefs: `
    type User {
      id: ID!
      email: String
    }

    type Query {
      userById(id: ID!): User
    }
  `
});

authorSchema = addMocksToSchema({schema: authorSchema});

const linkTypeDefs = `
  extend type User {
    chirps: [Chirp]
  }

  extend type Chirp {
    author: User
  }
`;


const typeDefs = stitchSchemas({
  subschemas: [
    {schema: chirpSchema,},
    {schema: authorSchema,},
  ],
  typeDefs: linkTypeDefs,
  resolvers: {
    Query: {
      chirpById: (_) => {
        console.log("chirpById");
        return {
          id: 12,
          text: "hahaha",
          authorId: 21
        };
      },
      chirpsByAuthorId: (_) => {
        console.log("chirpsByAuthorId");
        return [{
          id: 12,
          text: "hahaha",
          authorId: 21
        }];
      },
      userById: (_) => {
        console.log("userById");
        return {
          id: 21,
          email: "155@qq.com"
        }
      },
    },
    User: {
      chirps: {
        selectionSet: `{ id }`,
        resolve(user, args, context, info) {
          return delegateToSchema({
            schema: chirpSchema,
            operation: 'query',
            fieldName: 'chirpsByAuthorId',
            args: {
              authorId: user.id,
            },
            context,
            info,
          });
        },
      },
    },
    Chirp: {
      author: {
        selectionSet: `{ authorId }`,
        resolve(chirp, args, context, info) {
          return delegateToSchema({
            schema: authorSchema,
            operation: 'query',
            fieldName: 'userById',
            args: {
              id: chirp.authorId,
            },
            context,
            info,
          });
        },
      },
    },
  },
});

[yaacovCR]

That is what is coming from the original sub schema.

The hello world values comes from the mocks

[LeonYanghaha]

but I still don't know how to return the data in resolver. Not mock data. I deleted the code authorSchema = addMocksToSchema({schema: authorSchema}) but I got null. Can you tell me? Thank you very much.

[kamilkisiela]

but I still don't know how to return the data in resolver. Not mock data. I deleted the code authorSchema = addMocksToSchema({schema: authorSchema}) but I got null. Can you tell me? Thank you very much.

makeExecutableSchema({
  typeDefs: `
    type Query {
      test: String
    }
  `,
  resolvers: {
    Query: {
      test() {
        return 'Not Hello World';
      }
    }
  }
})

[LeonYanghaha]

Thank you very much. Your help is wonderful