Question

我有我的代码，还有一些问题。 1.如何使用“ updateMessage”突变？和 2.为什么我必须使用“消息类”？或使用该类有什么不同？

我知道如何为createMessage Mutation编写查询但我不知道该如何编写updateMessage突变。

var express = require('express');
var graphqlHTTP = require('express-graphql');
var {buildSchema } = require('graphql');

var schema = buildSchema(`
type Query{
    getMessage(id: ID!): Message
}
type Mutation {
    createMessage(input: MessageInput): Message
    updateMessage(id: ID!, input: MessageInput): Message
}

input MessageInput {
    content: String
    author: String
}

type Message {
    id: ID!
    content: String
    author: String
}
`);

class Message{
constructor(id,{content, author}){
    this.id = id;
    this.content = content;
    this.author = author;
}
};

var fakeDatabase = {};

var root = {
getMessage: function({id}){
    if(!fakeDatabase[id]){
        throw new Error('no message exists with id' + id);
    }
    return new Message(id, fakeDatabase[id]);
},
createMessage: function ({input}){
    var id = require('crypto').randomBytes(10).toString('hex');

    fakeDatabase[id]=input;
    return new Message(id, input);
},
updateMessage: function({id,input}){
    if (!fakeDatabase[id]){
        throw new Error('no message exists with id' +id);
    }
    fakeDatabase[id] = input;
    return new Message(id,input);
},
};


var app = express();

app.use('/graphql', graphqlHTTP({
schema: schema,
rootValue: root,
graphiql: true,
}));

app.listen (4000, ()=> console.log('Running a GraphQL API server at 
localhost:4000/graphql'));

Answer 1

问题1：

首先，您需要创建消息并从响应中获取消息ID

mutation {
  createMessage(input: {content:"this is content", author: "john"}) {
    id
    content
    author
  }
}

# response
{
  "data": {
    "createMessage": {
      "id": "956ea83a4ac8e27ff0ec",
      "content": "this is content",
      "author": "john"
    }
  }
}

然后使用消息ID更新消息

mutation {
  updateMessage(id: "956ea83a4ac8e27ff0ec", input: {content:"this is content", author: "john doe"}) {
    content
    author
  }
}

最后，检查消息是否已更新。

query {
  getMessage(id: "956ea83a4ac8e27ff0ec") {
    content
    author
  }
}

问题2： Message类充当模型类，在其中将相关字段封装到可以轻松重用的构造中。

如何在graphql中查询更新突变？

1 个答案: