Question

我正在使用异步响应来获取输出
我正在使用快递
我还将两个表数据合并为单个JSON响应

快递程序::

var express = require('express')
  , async = require('async')
  , http = require('http')
  , mysql = require('mysql'); 

var app = express();

var connection = mysql.createConnection({
    host: 'localhost',
    user: 'xxx',
    password: "xxx",
    database: 'test123'
});

connection.connect(); 

// all environments
app.set('port', process.env.PORT || 8084);


app.get('/',function(request,response){
    var first, second;

    async.series( [

        // Get the first table contents
        function ( callback ) {
            connection.query('SELECT * FROM test1', function(err, rows, fields)

                {
                        console.log('Connection result error '+err);
                        first = JSON.stringify(rows);
                        callback();
                });
        },

        // Get the second table contents
        function ( callback ) {
        connection.query('SELECT * FROM test2', function(err, rows, fields)

            {
                    console.log('Connection result error '+err);
                    second = JSON.stringify(rows);
                    callback();
            });
        }

   // Send the response
], function ( error, results ) {
    response.json({
        'first' : first,
        'second' : second
    });
} );

} );

http.createServer(app).listen(app.get('port'), function(){
  console.log('Express server listening on port ' + app.get('port'));
});

我需要在此处进行哪些代码更改

Answer 1

您可以更改以下功能：

function ( error, results ) {
    response.json({
        'first' : first,
        'second' : second
    });
}

到

function ( error, results ) {
    // case 1: since results is a js array object you can do following and is recommended
    res.json({first: results[0], second: results[0]});
    // case 2:else you can do the following thing as well. (Not recommended in this case of async)
    /* var jsonObj = JSON.parse('{first :' + first +', second : ' + second + '}');
    response.json(jsonObj); */
}

以下是输出：

{
  first :[{"_id":1,"name":"devrath","age":24},{"_id":2,"name":"Dheeraj","age":25},{"_id":3,"name":"Vikas","age":26}], 
  second : [{"_id":1,"place":"Hassan","phone":1},{"_id":2,"place":"Pune","phone":2},{"_id":3,"place":"Delhi","phone":3}]
}

在您的函数中，实际上变量的类型是字符串（而不是对象），因此您需要在发送响应之前将其解析为JSON（如case2）。但实际上你忘记了results对象本身，其中包含了所有async.series functions数组中的所有结果，所以你最好采用case 1中提到的results[0]来{ {1}}和first results[1]（在这种情况下，您可以忽略存储在变量本身，就像您second一样）

为了您的信息，您需要在回复之前设置first = JSON.stringify(rows);。如需更多，请查看快递docs

Answer 2

您不需要stringify来自MySql驱动程序的结果。此外，您不需要将结果存储到变量中，因为这正是async.js为您所做的事情。

因此，代码应如下所示：

var tasks = ['test1', 'test2'].map(function (table) {
  return function (callback) {
     connection.query('SELECT * FROM ' + table, function (err, rows) {
         if (err) {
           return callback(err);
         }

         callback(null, rows);
     });
  }
});

async.series(tasks, function (err, results) {
   if (err) {
     return res.send(500);
   }

   res.json({first: results[0], second: results[1]});
});

使用express生成输出....用于JSON输出

2 个答案: