javascript - GraphQL:field.resolve() 结果在指令内未定义

Question

我一直在关注在 Google 上找到的有关如何制定 AuthDirective 的所有结果，但我无法使其发挥作用。

我将保留所有文件，看看我是否在实现上犯了错误，但我想不会，因为我即使在 field.resolve 内没有任何条件的情况下也进行了测试。

我发现的一个特别的事情是 field.resolve 带有 4 个参数，其中第一个参数总是未定义，不确定是否可能是这样，但只是作为一个额外的提示。

所以这是代码:

这是我的 typedef 的一部分

directive @isAuthenticated on FIELD_DEFINITION

scalar Date

type User {
    id: ID,
    name: String
    email: String
    password: String
    createdAt: Date
}

type Token {
    token: String
}

# IF I REMOVE @isAuthenticated this works!
type Query {
    user(name: String): User! @isAuthenticated 
    users: [User!]! @isAuthenticated
}

type Mutation {
    createUser(name: String, email: String, password: String): Boolean!
    login(email: String!, password: String!): Token!
}

这是我的架构:

import path from 'path';
import { makeExecutableSchema } from 'graphql-tools';
import { fileLoader, mergeResolvers, mergeTypes } from 'merge-graphql-schemas';
import schemaDirectives from './Directives';

const typedefsArray = fileLoader(path.join(__dirname, './**/*.graphql'));
const resolversArray = fileLoader(path.join(__dirname, './**/*.resolvers.ts'));

const typeDefs = mergeTypes(typedefsArray);
const resolvers = mergeResolvers(resolversArray);
const schema = makeExecutableSchema({ typeDefs, resolvers, schemaDirectives });

export default schema;

这是我的 AuthDirective

import { defaultFieldResolver } from 'graphql';
import { AuthenticationError, SchemaDirectiveVisitor } from 'apollo-server-express';

class AuthDirective extends SchemaDirectiveVisitor {
  visitFieldDefinition(field: any) {
    const { resolver = defaultFieldResolver } = field;

    field.resolve = async function (...args: any) {
      const [_, __, context] = args;
      const { req } = context;
      const accessToken = req.headers.authorization
        ? req.headers.authorization.replace('Bearer ', '')
        : null;

      if (accessToken) {
        // here I was doing jwt.verify(accessToken) but I removed it for now to simplify
        const result = await resolver.apply(this, args);
        return result; // <--- THIS IS ALWAYS UNDEFINED
      } else {
        throw new AuthenticationError('Unauthorized field');
      }
    };
  }
}

export default AuthDirective;

它位于 ./Directives 下，并从索引导出为:

import AuthDirective from './auth';

export default {
  isAuthenticated: AuthDirective
}

最后是我的用户解析器。就像我之前说的，如果我从用户 graphql 查询中删除该指令，它就会正常工作:

import jwt from 'jsonwebtoken';
import { AuthenticationError, UserInputError } from 'apollo-server-express';
import { IUser } from './IUser';
import UserModel from './user.schema';
import { Config } from '../../config';

const { APP_SECRET } = Config;

const createToken = async (user: IUser, secret: string, expiresIn: string) => {
  const { id, email, name } = user;
  return jwt.sign({ id, email, name }, secret, { expiresIn });
};

const userResolvers = {
  Query: {
    user: (_: any, { name }: { name: string }) => UserModel.findOne({ name }).exec(),
    users: () => UserModel.find({}).exec()
  },
  Mutation: {
    createUser: async (_: any, args: IUser) => {
      await new UserModel(args).save();
      return true;
    },
    login: async (_: any, { email, password }: IUser) => {
      const user = await UserModel.findOne({ email }).exec();

      if (!user) {
        throw new UserInputError('No user found with this login credentials.');
      }

      const isValid = await user.validatePassword(password);

      if (!isValid) {
        throw new AuthenticationError('Invalid password.');
      }

      return { token: createToken(user, APP_SECRET, '30m') };
    }
  }
};

export default userResolvers;

和我的服务器:

import morgan from 'morgan';
import express from 'express';
import bodyParser from 'body-parser';
import compression from 'compression';
import depthLimit from 'graphql-depth-limit';
import { ApolloServer } from 'apollo-server-express';

import { Config, DBConfig } from './config';
import schema from './domain';
const { PORT } = Config;

const app = express();

const apolloServer = new ApolloServer({
  schema,
  validationRules: [depthLimit(7)],
  context: ({ req, res }: any) => ({ req, res })
});

app.use(express.json());
app.use(compression());
app.use(morgan('combined'));
app.use(bodyParser.urlencoded({ extended: true }));
apolloServer.applyMiddleware({ app });

DBConfig.init();

app.listen(PORT, () => console.log(`Server running on port ${PORT}`));

Answer 1

field 上没有 resolver 属性，因此这样

const { resolver = defaultFieldResolver } = field;

将始终导致 resolver 具有 defaultFieldResolver 的值。如果您在某个具有自定义解析器的字段上使用该指令，则永远不会调用该自定义解析器 - 仅使用默认行为，这确实可能返回 undefined。

您需要确保使用正确的属性:

const { resolve = defaultFieldResolver } = field;

或者您可以在解构字段时重命名结果变量:

const { resolve: resolver = defaultFieldResolver } = field;