I needed a DB for an alexa app, so I set up and and it INSERTS nicely, but when im trying to SELECT and save it to a variable the values saved to the variable are [Object Object] instead of wanted value, I know it can be async problem or parsing problem but i just cant fix the code, some help would be cool,
canHandle(handlerInput) {
return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest'
&& Alexa.getIntentName(handlerInput.requestEnvelope) === 'buscaIntent';
},
handle(handlerInput) {
const mysql = require('mysql');
const connection = mysql.createConnection
({
host: 'remotemysql.com',
user: 'RBb34534sd',
password: 'xxxxxxxxx',
database: 'RBsdfewrg'
});
var stat = connection.query('SELECT `spe` FROM `prueba` WHERE `nombre` LIKE "raichu" limit 1', function (err, result, fields) {
if (err) throw err;
console.log(result);
return result[0];
});
connection.end();
return handlerInput.responseBuilder
.speak("Busc " + stat)
.reprompt("reprompt buscar")
.getResponse();
}
}; ```
The issue is that you're not waiting for your database query to complete before sending your response to the Alexa service. Requests in node.js are non-blocking, meaning you either need to nest the request with a callback, or leverage Promises / async-await patterns so that the SQL query is processed before the function is fully executed.
You can read more on converting the built-in library for SQL connections to support Promises here, or use a library like this that already has a wrapper in place.
In either scenario, the end result would be refactored to something like this:
canHandle(handlerInput) {
return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest'
&& Alexa.getIntentName(handlerInput.requestEnvelope) === 'buscaIntent';
},
async handle(handlerInput) {
const mysql = require('mysql2/promise');
const connection = await mysql.createConnection
({
host: 'remotemysql.com',
user: 'RBb34534sd',
password: 'xxxxxxxxx',
database: 'RBsdfewrg'
});
var stat = await connection.execute('SELECT `spe` FROM `prueba` WHERE `nombre` LIKE "raichu" limit 1', function (err, result, fields) {
if (err) throw err;
console.log(result);
return result[0];
});
return handlerInput.responseBuilder
.speak("Busc " + stat)
.reprompt("reprompt buscar")
.getResponse();
}
Another article describing async calls for Alexa requests here.
I think the query is returning an object you can't keep the object in speech. Check what's inside the object and if you have a field that you want inside that object then access by stat.YourField.
Related
module.exports.handler = async (event, context, callback) => {
context.callbackWaitsForEmptyEventLoop = false;
let index = 0;
var client = mysql.createConnection({
host: process.env.rds_host,
user: process.env.rds_username,
password: process.env.rds_password,
port: process.env.rds_port
});
client.connect((err) => {
if (err) throw err;
console.log("Connected!");
});
let array = [];
let queries = ["query1", "query2", "query3", "query4"];
queries.map(q => {
array.push(getQueryResult(client, q));
});
Promise.all(array).then(result => {
console.log(result);
});
callback(null, {});
};
const getQueryResult = async (client, query) => {
return new Promise((resolve, reject) => {
client.query(query, function (err, result) {
if (err) {
reject(err);
}
resolve(result);
});
});
};
Above is my lambda scripts to execute multiple query from mysql. The problem is I didn't get any result and error message from above scripts. Please help me something is missing inside my scripts?
The issue is >> code is not waiting to finish Promise
You can resolve by :
Add callback in then
Promise.all(array).then(result => {
console.log(result);
callback(null, {});
});
OR
Use await
let result = await Promise.all(promiseArray);
console.log(result)
callback(null, {});
Note: Use try-catch to handle error in for await
Also, don't use map to loop array instead use For loop.
There are two or three (potential) issues with your code above:
Your if statement does not get evaluated because of the typeof client predicate does not return true.
your mysql port conflicts with your localhost port (assumption)
Change your if block as such:
// check if `dotenv` has been called if you use it
require('dotenv').config();
// access the state property on mysql object
// if you have closed your connection previously
// this will get evaluated by the parser
if (mysql.state === "disconnected") {
var client = mysql.createConnection({
host: process.env.rds_host,
user: process.env.rds_username,
password: process.env.rds_password,
port: process.env.rds_port // is your port the same as your localhost?
// include your database name here
});
// I suggest you to await your client connection
// since mysql executes sequentially, not asynchronously
client.connect(function(err) => {
if (err) {
console.error('error connecting: ' + err.stack);
return;
}
console.log("Connected!");
});
}
if the error persists, it means that your enviroment variables are not set correctly so your db configuration should be reviewed (see inline comments).
I am new to Meteor, I am using MySQL database instead of MongoDB. I want to return mysql records from one of the Meteor Method at server and I am try to return same and at client side I want to print them into console. But it is printing as 'undefined'.
server.js
----------
import { Meteor } from 'meteor/meteor';
import mysql from 'mysql';
import { Mongo } from 'meteor/mongo';
Meteor.methods({
insertJobCurrent:function(EMPLID,callback) {
var pool = mysql.createConnection({
host: '127.0.0.1',
user: 'root',
password: 'abc1234',
database: 'dbEmployees'
//port: '31597'
});
var JobCurrent=[];
pool.query("SELECT A.EMPLID, B.NAME, A.JOBCODE, A.DEPTID, A.JOB_ENTRY_DT, A.SUPERVISOR_ID FROM Employee A JOIN names B ON A.EMPLID=B.EMPLID WHERE A.ACTIVE='Y' AND A.EMPL_RCD=0 AND A.EMPLID='"+EMPLID +"'", function (error, results, fields){
console.log(results); // Printing the results in Meteor console
return results;
});
//return jobCurrent.find().fetch();
}
});
client.js
--------
Meteor.call('insertJobCurrent',employeeID, function(err, response){
if (err) {
console.log("error: "+ err);
console.log(response);
} else{
console.log(response); // Printing undefined
console.log("success")
}
});
How can get the results at client side? Appreciate if anyone help me!
This looks like a classic return value from callback problem:
How do I return the response from an asynchronous call?
I'm not sure how familiar you are with callbacks and asynchronous code, but the general flow of your function currently is:
** Method comes in
Create db connection
>> Send async query to mysql
** function ends and returns empty message to client -> client sees empty response
<< async function finishes and runs callback, result goes nowhere because response was already sent to client.
What you want to do is wait for the callback to finish first.
There’s three ways you can do this with Meteor
1. Use Meteor.wrapAsync
insertJobCurrent: function(EMPLID,callback) {
var pool = mysql.createConnection({
host: '127.0.0.1',
user: 'root',
password: 'abc1234',
database: 'dbEmployees'
//port: '31597'
});
// Wrap the function you want to call
// The second parameter sets `this` in the wrapped function.
// I have no idea if the mysql module you're using needs this, but I'm including it just in case
const wrappedmysqlQuery = Meteor.wrapAsync(pool.query, pool);
// Now you can call the wrapped function as though it was synchronous
const results = wrappedmysqlQuery("SELECT A.EMPLID, B.NAME, A.JOBCODE, A.DEPTID, A.JOB_ENTRY_DT, A.SUPERVISOR_ID FROM Employee A JOIN names B ON A.EMPLID=B.EMPLID WHERE A.ACTIVE='Y' AND A.EMPL_RCD=0 AND A.EMPLID='"+EMPLID +"'")
console.log(results); // Printing the results in Meteor console
return results;
}
Here's the docs on Meteor.wrapAsync:
https://docs.meteor.com/api/core.html#Meteor-wrapAsync
Long before Promises and async functions, Meteor provided sync style async calls on the server using Fibers. If you're curious, you can get a rundown here: https://benjamn.github.io/goto2015-talk/#/
2. Return a Promise:
insertJobCurrent: function(EMPLID,callback) {
var pool = mysql.createConnection({
host: '127.0.0.1',
user: 'root',
password: 'abc1234',
database: 'dbEmployees'
//port: '31597'
});
return new Promise(function (resolve, reject) {
pool.query("SELECT A.EMPLID, B.NAME, A.JOBCODE, A.DEPTID, A.JOB_ENTRY_DT, A.SUPERVISOR_ID FROM Employee A JOIN names B ON A.EMPLID=B.EMPLID WHERE A.ACTIVE='Y' AND A.EMPL_RCD=0 AND A.EMPLID='"+EMPLID +"'", function (error, results, fields) {
console.log(results); // Printing the results in Meteor console
resolve(results);
});
}))
}
This works because Meteor checks if you're returning a promise from a method and will automatically await the result before sending it to the client
3. Use Async/Await
async functions and async/await work best in when the library you're using already returns promises or if you can promisify the function in question.
I have't checked if mysql can return promises, so I'll use the pify module to promisify the function in the example
import pify from 'pify'
insertJobCurrent: async function(EMPLID,callback) {
var pool = mysql.createConnection({
host: '127.0.0.1',
user: 'root',
password: 'abc1234',
database: 'dbEmployees'
//port: '31597'
});
// promisify the function you want to call
const wrappedmysqlQuery = pify(pool.query);
// Now when we run the promisified function it returns a promise that we
// can wait for the value of with `await`
const results = await wrappedmysqlQuery("SELECT A.EMPLID, B.NAME, A.JOBCODE, A.DEPTID, A.JOB_ENTRY_DT, A.SUPERVISOR_ID FROM Employee A JOIN names B ON A.EMPLID=B.EMPLID WHERE A.ACTIVE='Y' AND A.EMPL_RCD=0 AND A.EMPLID='"+EMPLID +"'");
console.log(results); // Printing the results in Meteor console
return results;
}
Note that await is only available inside an async function. async functions always return a promise.
This one is most similar to the Meteor example, except that it uses pure javascript.
One notable difference is that when Meteor sees an async function it acts as though you ran this.unblock() inside the function, and so the order in which methods are called is not guarenteed (unlike with wrapAsync).
I am working on a discord.js bot, and I'm storing a bunch of information on various servers in a database. The problem is, that the code doesn't wait for the database to return the results. In the current situation, I'm trying to check if the server specific prefix checks out.
I tried using async and await at various places, but those didn't work. If I could, I'd rather not use .then(), because I don't really want to put all the commands inside a .then().
const { Client, Attachment, RichEmbed } = require('discord.js');
const client = new Client();
const mysql = require("mysql");
const config = require("./config.json")
var con = mysql.createConnection({
host: 'localhost',
user: 'root',
password: '',
database: 'botdb'
})
client.on("ready", () => {
console.log("I'm ready")
})
client.on("message", message => {
if (message.author.bot) return;
if (message.channel.type === 'dm') return;
let msg = message.content.split(" ");
let command = msg[0];
let prefix;
con.query(`SELECT * FROM serversettings WHERE ServerID = ${message.guild.id}`, (err, rows) => {
if (err) throw err;
prefix = rows[0].Prefix;
console.log(prefix)
})
console.log(`Prefix: ${prefix}, Command: ${command}`)
if (command === `${prefix}examplecommand`) {
//Do something
}
//Other code that uses prefix and command
}
It should log the prefix first, and then the Prefix: ${prefix}, Command: ${command} part, but it does it the other way around, so the examplecommand doesn't work.
Your result is caused by the fact that what's outside your query callback is executed immediately after the call. Keep in mind the mysql module is callback-based.
Possible Solutions
Place the code inside the callback so it's executed when the query is completed.
Wrap the query in a promise and await it.
function getGuild(guildID) {
return new Promise((resolve, reject) => {
con.query(`SELECT * FROM serversettings WHERE ServerID = '${guildID}', (err, rows) => {
if (err) return reject(err);
resolve(rows);
});
});
}
const [guild] = await getGuild(message.guild.id) // destructuring 'rows' array
.catch(console.error);
console.log(guild.prefix);
Use a Promise-based version of a MySQL wrapper, like promise-mysql. You could use it the same way as the code above, without worrying about coding your own Promises.
const [guild] = await con.query(`SELECT * FROM serversettings WHERE serverID = '${message.guild.id}'`)
.catch(console.error);
console.log(guild.prefix);
I'm trying to write a JSON object (or string, unsure) to my mysql database using node.js. I first retrieved the JSON via an xml url using xml2js. I am able to log the json string result in my console via JSON.stringify, but I am unsure how to proceed from here.
Here is the url I took the xml from: https://water.weather.gov/ahps2/hydrograph_to_xml.php?gage=deld1&output=xml
I would like to write each instance from the JSON string to a row, with the columns as the name of the data. It would look something like this:
Here is my code in index.js, which I enact with node index.js on the console:
var parseString = require('xml2js').parseString;
var http = require('http');
var https = require('https');
var mysql = require('mysql');
var con = mysql.createConnection({
host: "localhost",
user: "root",
password: "password",
database: "mydb"
});
function xmlToJson(url, callback) {
var req = https.get(url, function(res) {
var xml = '';
res.on('data', function(chunk) {
xml += chunk;
});
res.on('error', function(e) {
callback(e, null);
});
res.on('timeout', function(e) {
callback(e, null);
});
res.on('end', function() {
parseString(xml, function(err, result) {
callback(null, result);
});
});
});
}
var url = "https://water.weather.gov/ahps2/hydrograph_to_xml.php?gage=deld1&output=xml"
xmlToJson(url, function(err, data) {
if (err) {
return console.err(err);
}
strungout = JSON.stringify(data, null, 1);
console.log(strungout);
//strungout contains my json string
})
con.connect(function(err) {
if (err) throw err;
//below is where I might make an insert statement to insert my values into a mysql table
var sql = someinsertstatement
con.query(sql, function (err, result) {
if (err) throw err;
console.log("records inserted");
res.end();
});
});
As mentioned, when I run the above code in my console, the console returns the JSON, though I am unsure how to assign this to a variable that I can then write into my mysql database.
Alternatively, if there is an easier way to write xml from a website directly to my mysql database, I would certainly appreciate any pointers. I feel like it should be easier than this, but I am new to pretty much all of it.
EDIT:
Adding the JSON. I removed the line breaks to consolidate it. Trying to assign the result '4.68' to a variable.
data = {"site": {"observed": [{"datum": [{"valid": [{"_": "2019-02-21T19:42:00-00:00","$": {"timezone": "UTC"}}],"primary": [{"_": "4.68","$": {"name": "Stage","units": "ft"}}]}]}]}};
Thank you.
This worked on my end. Found that the main data you seek is site.observed.datum
const parser = require('xml2json');
const request = require("request");
var mysql = require('mysql');
var con = mysql.createConnection({
host: "localhost",
user: "root",
password: "password",
database: "mydb"
});
var api_url = 'https://water.weather.gov/ahps2/hydrograph_to_xml.php?gage=deld1&output=xml';
function xmlToJson(url, callback){
return request({
method: 'GET',
url: api_url,
}, function (error, response, body) {
if (error) {
return callback({
errorResponse: error,
rowsToInsert: false
});
}else{
let jsonRes = JSON.parse(parser.toJson(body));
let datumResult = jsonRes.site.observed.datum;//I had to log Object.keys multple time to get the
const readyForDB = datumResult.map(x => {
let timeOfReading = x.valid.$t;
let stage = x.primary.$t;
let flow = x.secondary.$t;
return [
timeOfReading, stage, flow
]
});
return callback({
errorResponse: false,
rowsToInsert: readyForDB
});
}
})
}
return xmlToJson(api_url, ({errorResponse, rowsToInsert}) => {
if(errorResponse){
throw callback.errorResponse;
}
return con.connect(function(err) {
if (err) throw err;
//below is where I might make an insert statement to insert my values into a mysql table
var sql = "INSERT INTO forecast (timeOfReading, stage, flow) VALUES ?"
con.query(sql, [rowsToInsert], function (err, result) {
if (err) throw err;
console.log(result.affectedRows + " rows inserted");
});
});
});
Sounds like you have the JSON you want but are unsure how to access data within it. Correct me if I'm wrong.
Lets say you have this JSON object called "test":
{
a:1
b:{
x:2
}
}
You can access the value of 1 by calling test.a, and similarly access the value of 2 by calling test.b.x
I am getting strange behavior using Node.JS and MySQL with this driver - https://github.com/mysqljs/mysql
Essentially, I have a button on the frontend that triggers an app.get that makes a query in the database and I can happily use the results in my backend.
This works nicely, until I press the button 4-5 times in a second, where as the queries lock up and I have to wait for 2-3 minutes until they continue executing. I have a similar write function that behaves the same way.
Is it possible this is a problem, because I'm trying to execute the exact same query asynchronously? I.e. do I have to limit this from the front end or is it a backend problem?
Any ideas on how to debug what exactly is going on?
// database.js
var mysql = require('mysql');
var pool = mysql.createPool({
connectionLimit: 100,
host : 'localhost',
user : 'secret',
password : 'secret',
database : 'mydb'
});
exports.getConnection = function(callback) {
pool.getConnection(function(err, connection) {
callback(err, connection);
});
};
// dbrw.js
var con = require('../config/database');
function read(id, done) {
con.getConnection(function(err, connection){
if(!err){
connection.query("SELECT * FROM users WHERE id = ?",[id], function(err, rows) {
connection.release();
if (err)
done(err);
if (rows.length) {
console.log("rows " + JSON.stringify(rows));
done(rows[0].progress);
};
});
}
else {
console.log(err);
}
});
}
exports.read = read;
// routes.js
var dbrw = require('./dbrw.js');
app.get('/read', isLoggedIn, function(req, res) {
dbrw.read(req.user.id, function(result) {
console.log(result);
});
});
// Frontend - angular app.js
$scope.tryread = function() {
$http.get('/read');
}
Thanks in advance for any input.
I see a few issues:
function read(id, done) {
con.getConnection(function(id, connection){...}
}
Notice how you overwrite the id passed to read by giving that same name to an argument of the callback to getConnection.
Also, your Express route doesn't actually end the request by sending back a response, which will make your browser time out the connection. At some point, it will even refuse to send more requests because too many are still pending.
So make sure to end the request:
app.get('/read', isLoggedIn, function(req, res) {
dbrw.read(req.user.id, function(result) {
console.log(result);
res.end(); // or `res.send(result)`
});
});
And a tip: you should use the callback calling convertion for Node, where the first argument represents an error (if there is any) and the second argument represents the return value.