[英]MySQL, Node.js Sequential actions - How can I do that?
我有以下代码:
function query1() {
var defered = Q.defer();
console.log("In query1");
var connection = mysql.createConnection({
host: '........',
user: 'm...c....a.....i',
password: '......Z....9...K',
database: '.....ol'
});
connection.connect(function(err) {
if (!err) {
console.log("Database is connected ...");
} else {
console.log("Error connecting database ...");
}
});
sql = '' +
'select c.ID as CENA_ID, ' +
' c.I_KEY as CENA_NUMERO, ' +
' c.NM_CENA as CENA_NOME, ' +
' b.DS_MAC as MAC_BOX, ' +
' v.DS_CLIENTID as ALEXA_ID, ' +
' v.FK_ID_GRUPO as GRUPO_ID ' +
' from TB_DISPOSITIVOS_VOZ v ' +
' inner join TB_GRUPOS g ' +
' on g.ID = v.FK_ID_GRUPO ' +
' inner join TB_CENAS c ' +
' on g.ID = c.FK_ID_GRUPO ' +
' inner join TB_CENTRAIS b ' +
' on g.ID = b.FK_ID_GRUPO ' +
'where v.DS_CLIENTID = "' + userId + '" ' +
'and lower(c.NM_CENA) like "%' + sceneName.toLowerCase() + '%"';
console.log("Created query");
try{
connection.query(sql, function(erro, rows, fields) {
if (!erro) {
console.log("Executed query verifying the userId");
contador = 0;
if (rows.length > 0) {
cena_id = rows[0].CENA_ID;
cena_numero = rows[0].CENA_NUMERO;
cena_nome = rows[0].CENA_NOME;
alexa_id = rows[0].ALEXA_ID;
grupo_id = rows[0].GRUPO_ID;
mac_box = rows[0].MAC_BOX;
contador = contador + 1;
}
console.log("contador: " + contador);
} else {
console.log("Error - getting the Alexa register in database" + erro);
context.fail("Error - getting the Alexa register in database" + erro);
}
});
}catch (ex){
console.log("exception: " + ex);
}
}
以及以下代码:
Q.all([query1()]).then(function(results) {
console.log("Q.all log function");
if (contador > 0) {
console.log("contador > 0");
var client = mqtt.connect('mqtt://.............com');
console.log("connected to MQTT broker");
var buffer = [26,
0,0,0,0,555,645,0,0,0,0,0,
0,5555,2,Math.floor((Math.random() * 200) + 1),
0,0,0,333,13,4,0,1,0,
cena_numero
];
console.log("Created buffer");
client.on('connect', function() {
client.publish('n/c/' + mac_box + '/app', buffer);
console.log("sent MQTT");
});
speechOutput = "Command " + sceneName + " executed successfully";
repromptText = "";
console.log("Process executed successfully")
} else {
console.log("contador <= 0");
speechOutput = "This command was not found!";
repromptText = "";
}
}, function (reason) {
console.log("reason: " + reason);
});
仅在第一个query1()
正确执行的情况下,如何执行第二个代码? 因为在函数query1()
我有一个MySQL查询,所以我只能在查询结果之后继续执行该过程。
有人可以帮助我吗?
非常感谢!
您缺少与Node.js中的回调和异步行为有关的一些关键概念。 您正在使用“ Q”库(顺便说一句,我建议尝试使用bluebird)来处理promise,但是您的“ query1”函数不会返回promise。 这就是为什么执行query1但在query1完成之前将执行“ Q.all日志功能”的原因。
您可以改为这样来构造代码(由于我更熟悉蓝鸟,因此我将举一个例子):
var Promise = require('bluebird');
var _connection;
function query1() {
return new Promise(resolve, reject) {
//open your connection
connection.open(function (err, connection) {
if (err) return reject(err);
_connection = connection;
//do your query
_connection.query(sql, [params], function (err, data) {
if (err) return reject(err);
else resolve(data);
});
});
});
}
function query2(data) {
return new Promise(resolve, reject) {
//do your query, using data passed in from query1
_connection.query(sql, [params], function (err, data) {
if (err) return reject(err);
else resolve(data);
});
});
}
query1
.then(function (data) { query2(data); })
.catch(function (err) {
console.log('error:', err);
});
另外,仅供参考,串联SQL字符串是一个禁忌,这将使您容易受到SQL注入攻击:
like "%' + sceneName.toLowerCase() + '%"
而是使用like "%?%"
并通过connection.query(sql, [sceneName], function(err, data) {})
调用您的SQL。 希望这可以帮助。
我用这样的async
包解决了我的问题:
var async = require('async');
async.series([
function(callback) {
//action 1...
},
function(callback){
//action 2...
}
], function(err) {
if (err) {
speechOutput = "Scene not found!";
repromptText = "Please try again.";
}
console.log("Before speechOutput");
callback(sessionAttributes,
buildSpeechletResponse(cardTitle, speechOutput, repromptText, shouldEndSession));
});
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