GraphQL:在GraphQLObjectType中使用自定义类型定义GraphQLList时出错
GraphQL:在GraphQLObjectType中使用自定义类型定义GraphQLList时出错
提问于 2018-04-13 14:39:06
我想学习GraphQL，我正在编写一个表示图书商店的示例，用户可以在其中编写多本书的作者。
我的问题是，我不能在BookType( UserType，GraphQLObjectType)中定义一个类型为“UserType”的列表。奇怪的是，当BookType有一个作者时，它不会抛出错误。
user.js (UserType)：
const {
GraphQLList,
GraphQLID,
GraphQLString,
GraphQLObjectType,
GraphQLNonNull,
GraphQLInt,
} = require('graphql');
const BookType = require('./book');
const BookSchema = require('../db/models/book');
console.log(BookType);
module.exports = new GraphQLObjectType({
name: 'User',
fields: () => ({
id: { type: new GraphQLNonNull(GraphQLID) },
name: { type: new GraphQLNonNull(GraphQLString) },
books: {
type: new GraphQLList(BookType),
resolve(parent, args){
return BookSchema.find({_id: parent.id});
}
}
})
});book.js (BookType)：
const {
GraphQLID,
GraphQLString,
GraphQLObjectType,
GraphQLNonNull,
GraphQLInt } = require('graphql');
const UserType = require('./user');
const UserSchema = require('../db/models/user');
console.log(UserType);
module.exports = new GraphQLObjectType({
name: 'Book',
fields: () => ({
id: { type: new GraphQLNonNull(GraphQLID) },
author: {
type: UserType,
resolve(parent, args){
return UserSchema.findOne({_id: parent.author});
}
},
title: { type: new GraphQLNonNull(GraphQLString) },
sites: { type: new GraphQLNonNull(GraphQLInt) }
})
});如您所见，我记录了、BookType、和UserType。奇怪的是，当我记录BookType时，会得到一个空对象。
输出：
console.log(BookType) --> {}
console.log(UserType) --> User以下是错误：
Error: Expected [object Object] to be a GraphQL type.
at invariant (/media/lorenz/DATA/Privat/Programmieren/JavaScript/NodeJS/bookShop/node_modules/graphql/jsutils/invariant.js:19:11)
at assertType (/media/lorenz/DATA/Privat/Programmieren/JavaScript/NodeJS/bookShop/node_modules/graphql/type/definition.js:88:43)
at new GraphQLList (/media/lorenz/DATA/Privat/Programmieren/JavaScript/NodeJS/bookShop/node_modules/graphql/type/definition.js:258:19)
at fields (/media/lorenz/DATA/Privat/Programmieren/JavaScript/NodeJS/bookShop/src/types/user.js:21:19)
at resolveThunk (/media/lorenz/DATA/Privat/Programmieren/JavaScript/NodeJS/bookShop/node_modules/graphql/type/definition.js:370:40)
at defineFieldMap (/media/lorenz/DATA/Privat/Programmieren/JavaScript/NodeJS/bookShop/node_modules/graphql/type/definition.js:532:18)
at GraphQLObjectType.getFields (/media/lorenz/DATA/Privat/Programmieren/JavaScript/NodeJS/bookShop/node_modules/graphql/type/definition.js:506:44)
at typeMapReducer (/media/lorenz/DATA/Privat/Programmieren/JavaScript/NodeJS/bookShop/node_modules/graphql/type/schema.js:232:38)
at /media/lorenz/DATA/Privat/Programmieren/JavaScript/NodeJS/bookShop/node_modules/graphql/type/schema.js:239:20
at Array.forEach (<anonymous>)
at typeMapReducer (/media/lorenz/DATA/Privat/Programmieren/JavaScript/NodeJS/bookShop/node_modules/graphql/type/schema.js:232:51)
at /media/lorenz/DATA/Privat/Programmieren/JavaScript/NodeJS/bookShop/node_modules/graphql/type/schema.js:239:20
at Array.forEach (<anonymous>)
at typeMapReducer (/media/lorenz/DATA/Privat/Programmieren/JavaScript/NodeJS/bookShop/node_modules/graphql/type/schema.js:232:51)
at Array.reduce (<anonymous>)
at new GraphQLSchema (/media/lorenz/DATA/Privat/Programmieren/JavaScript/NodeJS/bookShop/node_modules/graphql/type/schema.js:122:28)回答 1
Stack Overflow用户
回答已采纳
发布于 2018-05-03 19:20:37
你在这里重复了很多代码。我将开始创建一个名为schema.js的文件。
开发您的RootQuery的工作，下面是一个可以帮助您的示例：
const RootQuery = new GraphQLObjectType({
name: 'RootQueryType',
fields: {
user: {
type: UserType,
args: { id: { type: GraphQLString } },
resolve(parentValue, args) {
return axios
.get(`http://localhost:3000/users/${args.id}`)
.then(res => res.data);
}
},
company: {
type: CompanyType,
args: { id: { type: GraphQLString } },
resolve(parentValue, args) {
return axios
.get(`http://localhost:3000/companies/${args.id}`)
.then(res => res.data);
}
}
}
});然后导出，然后为UserType和其他人创建函数。这方面的一个例子是：
const UserType = new GraphQLObjectType({
name: 'User',
fields: () => ({
id: { type: GraphQLString },
firstName: { type: GraphQLString },
age: { type: GraphQLInt },
company: {
type: CompanyType,
resolve(parentValue, args) {
return axios
.get(`http://localhost:3000/companies/${parentValue.companyId}`)
.then(res => res.data);
}
}
})
});因此，与其导出每个GraphQLObjectType，不如只导出一次
module.exports = new GraphQLSchema({ query: RootQuery });页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/49819507
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