如何修复 GraphQL 中继连接的循环依赖

Question

我已经将我的连接分离到它自己的文件中，并且可以在我的根查询中使用它（当在类型中定义连接时它工作正常），但是当试图通过将它导入到类型中来使用它时连接是为了我刚回来：

Error: PageEdge.node field type must be Output Type but got: undefined

我可以让连接在我的 QueryType 中工作，但不能在 PageType 中工作。我的架构大致是这样的。

QueryType {
  pages: [PageType]
}

PageType {
  _id: string
  pages: [PageType]
}

这是一个 link 到项目仓库的 graphql 东西所在的地方（我只是推送了一个提交，它错误地查看了所有代码）： https://github.com/DaveyEdwards/myiworlds/tree/master/src/data

我已经对 QueryType 和 PageType 字段进行了 thunk（似乎可以解决大多数人的问题的解决方案）并且还尝试从接口中进行 thunk：

interfaces: () => [nodeInterface]

我认为对于任何与用户和朋友一起构建应用程序的人来说，这是一个非常普遍的问题。

UserType: {
  friends: [UserType]
}

我的页面类型：

import { nodeInterface } from '../nodeInterface';
import PageConnection from './connections/PageConnection';

const PageType = new ObjectType({
  name: 'Page',
  description: 'Everything you see can be placed inside a page.',
  fields: () => ({
    id: globalIdField('Page', page => page._id),
    _id: {
      type: new NonNull(ID),
      description: 'A unique id used to instantly locate this page inside the database',
    },
    pageEdge: {
      type: PageConnection,
      args: connectionArgs,
      resolve: async (page, { args }, { loaders }) => {
        if (page.pageEdge) {
          const pageEdge = await loaders.pageLoader.loadMany(page.pageEdge);
          const connection = connectionFromArray(pageEdge, args);
          return connection;
        }
      },
    },
  }),
  interfaces: () => [nodeInterface],
});

export default PageType;

我的页面连接：

import { connectionDefinitions } from 'graphql-relay';

import PageType from '../PageType';

const { connectionType: PageConnection } = connectionDefinitions({
  name: 'Page',
  nodeType: PageType,
});

export default PageConnection;

我的节点接口：

import { nodeDefinitions } from 'graphql-relay';
import { getNode, getNodeType } from './type-registry';

export const { nodeInterface, nodeField } = nodeDefinitions(getNode, getNodeType);

我的类型注册表：

import { fromGlobalId } from 'graphql-relay';
require('babel-polyfill');

const types = {};

export const registerType = (model, type, lookupFn) => {
  types[type.name] = { model, type, lookupFn };
};

export const getNode = async (globalId) => {
  const { type: typeName, id } = fromGlobalId(globalId);
  console.log('getNode', globalId, typeName, id);

  if (types[typeName]) {
    const object1 = await types[typeName].lookupFn(id);
    const Class = types[typeName].model;
    // let result  = Object.create(types[typeName].model, object1);
    const result = new Class(object1);
    console.log('getNode result', result);
    return result;
  }
  return null;
};

export const getNodeType = (obj) => {
  const keys = Object.keys(types);
  let ret = null;
  keys.map((typeName) => {
    if (obj instanceof types[typeName].model) {
      ret = types[typeName].type;
    }
    return true;
  });
  return ret;
};

导入连接工作的我的 QueryType

import {
  GraphQLObjectType as ObjectType,
  GraphQLList as List,
  GraphQLString as StringType,
} from 'graphql';
import { connectionArgs, connectionFromArray, connectionDefinitions } from 'graphql-relay';
import { nodeField } from '../nodeInterface';
import PageType from './PageType';
import { getPageList } from '../queries/googleDatastore/pageQueries';
import PageConnection from './connections/PageConnection';

const QueryType = new ObjectType({
  name: 'QueryType',
  fields: () => ({
    pages: {
      type: PageConnection,
      args: connectionArgs,
      resolve: async (obj, args) => {
        const response = [];
        try {
          const pageEdge = await getPageList();
          const connection = connectionFromArray(pageEdge, args);
          return connection;
        } catch (err) {
          console.log('pages err', err);
        }
        return response;
      },
    },
    node: nodeField,
  }),
});

export default QueryType;

我一直在努力解决这个问题的资源：

这个 repo 的一部分是我首先实现的让连接工作的东西 https://github.com/bondz/learn-graphql-relay/blob/47211fdec44ce4bb10f487bddfc7411e5690b894/src/types/projectConnection.js

Edge.node field type must be Output Type but got: undefined

https://github.com/graphql/graphql-js/issues/612

https://github.com/graphql/graphql-js/issues/373

https://gist.github.com/fbaiodias/77406c29ddf37fe46c3c

Answer 1

只需删除 PageType.js 顶部的 import PageConnection 并使用运行时要求：

...
pageEdge: {
  type: require('./connections/PageConnection'),
  args: connectionArgs,
...

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