使用 react js 和 express API 服务器发布一个带有 fetch 的对象

问题描述

我在使用 fetch 中的 post 方法时遇到问题，因为我的服务器正在从客户端接收一个空对象.我已在客户端签入，无法发送我要发送的值.

I am getting troubles with the post method in fetch because my server is receiving an empty object from the client. I've checked in the client side and can't send the value that I want to send.

这是我的服务器:

const express = require('express');
const app = express();
const bodyParser = require('body-parser');
const mysql = require('mysql');

app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
    extended: true
}));

// connection configurations
const mc = mysql.createConnection({
    host: 'localhost',
    user: 'root',
    password: '12345',
    database: 'node_task_demo',
    //socketPath: '/Applications/MAMP/tmp/mysql/mysql.sock'
});

// connect to database
mc.connect();

// default route
app.get('/', function (req, res) {
    return res.send({ error: true, message: 'hello' })
});

// Here where I'm calling in the client side
app.get('/todos', function (req, res) {
    mc.query('SELECT * FROM tasks', function (error, results, fields) {
        if (error) throw error;
        return res.send({ error: false, data: results, message: 'Todo list' });
    });
});

// Search for todos with ‘bug’ in their name
app.get('/todos/search/:keyword', function (req, res) {
  var mensaje = 'Todos search list.';
    let keyword = req.params.keyword;
    mc.query("SELECT * FROM tasks WHERE task LIKE ? ", ['%' + keyword + '%'], function (error, results, fields) {
        if (error) throw error;
        return res.send({ error: false, data: results, message: mensaje});
    });
});

// Retrieve todo with id
app.get('/todo/:id', function (req, res) {

    let task_id = req.params.id;

    if (!task_id) {
        return res.status(400).send({ error: true, message: 'Please provide task_id' });
    }

    mc.query('SELECT * FROM tasks where id=?', task_id, function (error, results, fields) {
        if (error) throw error;
        return res.send({ error: false, data: results[0], message: 'Todos list.' });
    });

});

// Add a new todo
app.post('/todo/meterla', function (req, res) {

    let task = req.body.task;

    if (!task) {
        return res.status(400).send({ error:true, message: 'Please provide task' });
    }

    //var task = req.body.task;

    var query = mc.query("INSERT INTO tasks SET ? ", { task: task}, function (error, results, fields) {
        if (error) throw error;
        console.log(task);
        return res.send({ error: false, data: results, message: 'New task has been created successfully.' });
    });
});

//  Update todo with id
app.put('/todo', function (req, res) {

    let task_id = req.body.task_id;
    let task = req.body.task;

    if (!task_id || !task) {
        return res.status(400).send({ error: task, message: 'Please provide task and task_id' });
    }

    mc.query("UPDATE tasks SET task = ? WHERE id = ?", [task, task_id], function (error, results, fields) {
        if (error) throw error;
        return res.send({ error: false, data: results, message: 'Task has been updated successfully.' });
    });
});

//  Delete todo
app.delete('/todo', function (req, res) {

    let task_id = req.body.task_id;

    if (!task_id) {
        return res.status(400).send({ error: true, message: 'Please provide task_id' });
    }
    mc.query('DELETE FROM tasks WHERE id = ?', [task_id], function (error, results, fields) {
        if (error) throw error;
        return res.send({ error: false, data: results, message: 'Task has been updated successfully.' });
    });
});

// all other requests redirect to 404
app.all("*", function (req, res, next) {
    return res.send('page not found');
    next();
});

// port must be set to 8080 because incoming http requests are routed from port 80 to port 8080
app.listen(8081, function () {
    console.log('Escuchando por el puerto 8081');
});

// allows "grunt dev" to create a development server with livereload
module.exports = app;

这是我的客户:

import React, { Component } from 'react';
import logo from './logo.svg';
import './App.css';

class App extends Component {

  constructor(props) {
    super(props);
    this.state = {data: ""};
    this.state_2 = {message: []};
    this.onSubmit = this.handleSubmit.bind(this);
  }

  componentDidMount() {
     fetch('/todo/1')
    .then((response) => response.json())
    .then((responseJson) =>{
      this.setState({
        message: responseJson.data
      });
    })
  }

handleSubmit(e){
  e.preventDefault();
  var self = this;
  // On submit of the form, send a POST request with the data to the server.
  fetch('/todo/meterla',{
    method: 'POST',
    body:{
      task: self.refs.task.value
    }
  })
  .then(function(response){
    return response.json()
  }).then(function(body){
    console.log(body);
    alert(self.refs.task.value)
  });
}

  render() {
    return (
      <div className="App">
        <div className="App-header">
          <img src={logo} className="App-logo" alt="logo" />
          <h2>Welcome to React</h2>
        </div>
        <form onSubmit={this.onSubmit}>
          <input type="text" placeholder="task" ref="task"/>
          <input type="submit"/>
        </form>
        <p className="App-intro">
          Este es el resultado de la consulta = <b>{JSON.stringify(this.state.message)}</b>
        </p>
      </div>
    );
  }
}

export default App;

推荐答案

body 必须是 stringified + 不要忘记 content-type

body must be stringified + don't forget the content-type

 fetch('/todo/meterla',{
    method: 'POST',
    body: JSON.stringify({
      task: self.refs.task.value
    }),
    headers: {"Content-Type": "application/json"}
  })
  .then(function(response){
    return response.json()
  }).then(function(body){
    console.log(body);
    alert(self.refs.task.value)
  });

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