Question

我想在async.series块的第三个函数中调用self.setState( { date_data: tour_dates});。所以我有一个嵌套的函数，似乎甚至在每个块上使用.bind（this）似乎都没有解决我的问题。我错过了什么？我应该如何改变我的编码风格以避免这样的问题？

var mysql = require('mysql');

var async = require('async');

var self = this;
var moment = require('moment');

class ArtistTable extends React.Component {
  constructor(props, context) {
    super(props, context);
    this.getArtistData = this.getArtistData.bind(this);
    this.state = {
      open: false,
      date_data: [],
    };
  }

  getArtistData (artistName) {

    var artist_id = -1;
    var tour_id = -1;
    var tour_dates = new Array();
    var connection = mysql.createConnection({
        host     : '127.0.0.1',
        user     : 'root',
        password : '',
        database : 'anand2'
    });

    connection.connect(function(err) {
        if (err) {
            console.error('MYSQL Error Connecting!' + err.stack);
            return;
        }
        console.log('MYSQL ArtistTable connected as ' + connection.threadId);
    });

    async.series([
        function(callback){
             connection.query("SELECT * FROM artist WHERE name = '" +artistName+"'" , function(err, rows){
                 artist_id = rows[0].id;
                 callback();
             });
         },  function(callback){
             //finde tour ID
             connection.query("SELECT * FROM tour WHERE artist = " + artist_id , function(err, rows){

                 console.log("SELECT * FROM tour WHERE artist = " + artist_id ) //Todo: neue erstellen
                 console.log(rows.length)
                 tour_id = rows[0].id;

                 console.log("Tour ID is " + tour_id)
                 callback();
            });
        }, function(callback){
            connection.query("SELECT dtime,location FROM tour_date WHERE tour="+ tour_id + " AND dtime >= CurDate() ORDER BY dtime ASC" , function(err, rows){
                if (rows.length > 0) {
                    for (var i = 0; i < rows.length; i++) {
                         tour_dates.push({date: rows[i].dtime, location:  rows[i].location });
                    }
                    console.log("Number of dates: " + tour_dates.length)
                    self.setState( { date_data: tour_dates});
                }
            }.bind(this));
        }
    ]);
  }
}

另外，请忽略“self = this”，这是一个测试，我确实试过了。

Answer 1

你需要在async.series之前将self = this放在getArtistData中。

React：组件函数中未定义“this”

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