架构必须是 GraphQLSchema 的一个实例。确保 node_modules 目录中没有安装多个版本的 GraphQL

Question

我在 graphiql 中有错误

"message": "Schema must be an instance of GraphQLSchema. Also ensure that there are not multiple versions of GraphQL installed in your node_modules directory."

我试过了find node_modules -name graphql。但是我只有一个版本的 graphql。

schema.js

import {
 GraphQLObjectType,
 GraphQLSchema,
 GraphQLInt
 } from 'graphql';

 let count = 0;

  let schema = new GraphQLSchema({
  query: new GraphQLObjectType({
    name: 'RootQueryType',
    fields: {
      count: {
        type: GraphQLInt,
        resolve: function() {
          return count;
        }
      }
    }
  })
});
export default schema;

package.json

"dependencies": {
    "babel-core": "^6.26.0",
    "babel-loader": "^7.1.2",
    "babel-preset-es2015": "^6.24.1",
    "babel-preset-react": "^6.24.1",
    "babel-preset-stage-1": "^6.24.1",
    "express": "^4.16.2",
    "express-graphql": "^0.6.11",
    "graphql": "^0.11.7",
    "mysql": "^2.15.0",
    "react": "^16.2.0",
    "react-dom": "^16.2.0",
    "react-relay": "^1.4.1",
    "require-clean": "^0.1.3",
    "webpack": "^3.8.1",
    "webpack-dev-server": "^2.9.5"
  }

server.js

import express from 'express';
import graphQLHTTP from 'express-graphql';
var Schema = require('./data/schema');
const GRAPHQL_PORT = 8080;
let graphQLServer;

 const graphQLApp = express();
  graphQLApp.use('/', graphQLHTTP({
    graphiql: true,
    pretty: true,
    schema: Schema,
  }));
  graphQLServer = graphQLApp.listen(GRAPHQL_PORT, () => {
    console.log(
      GraphQL server is now running.
 );
 });

服务器运行良好而且我可以在控制台中获取 GraphQL 服务器运行。但是 graphiql 显示错误。

知道其中有什么问题吗？

Answer 1

schema.js 中存在语法错误。 fields 是函数属性。这行得通。

let schema = new GraphQLSchema({
  query: new GraphQLObjectType({
    name: 'RootQueryType',
    fields: ()=> ({ 
      count: {
        type: GraphQLInt,
        resolve:()=> {
          return count;
        }
      }
    })
  })
});

server.js

import Schema from './data/schema';

架构必须是 GraphQLSchema 的一个实例。确保 node_modules 目录中没有安装多个版本的 GraphQL

Schema must be an instance of GraphQLSchema. Ensure that there are not multiple versions of GraphQL installed in your node_modules directory

graphql-js