Noob question. I'm trying to write an Apollo Server GraphQL resolver that will query and return a user from a MySQL database.
This is what I have so far:
const UserQueries = {
user: (_, args, { pool }) => {
let data = {};
pool.query(
"SELECT * FROM user_table WHERE `id` = ?",
[args.id],
(err, rows) => {
if (err) throw err;
else {
data.id = rows[0].id;
data.name = rows[0].name;
data.username = rows[0].username;
data.email = rows[0].email;
}
}
);
return data;
},
};
pool is the mysql2 connection pool. If I console log inside that else statement I am getting the correct data back from the database. The problem is I can't make it go into that variable. If I move the return statement inside the else statement it still doesn't work.
Definitely a noob question but I'm totally stuck. Thanks.
I think it should work, you should check your typedef, whether the response (data object fields) matches with the respective typedef fields or not.
Related
I'm using a tutorial to do JWT/bcryptjs auth and then INSERT into a SQlite
table.
Thing is the tutorial is for MySQL and I get errors like db.query is not a function
and db.escape is not a function
The db :
const sqlite3 = require('sqlite3').verbose()
const DBSOURCE = "./src/db/db.sqlite"
let db = new sqlite3.Database(DBSOURCE, (err) => {
if (err) {
// Cannot open database
console.error(err.message)
throw err
}else{
console.log('Connected to the SQLite database.')
}
});
module.exports = db
Example query :
db.query(
`SELECT * FROM users WHERE LOWER(username) = LOWER(${db.escape(
req.body.username
)});`,
(err, result) => {
if (result.length) {
return res.status(409).send({
msg: 'This username is already in use!'
});
} else { .........
My best guess is that the functions are different?
How do I get this right?
There are a lot of proprietary functions in MySQL that will not work with standard SQL in other database systems.
That is just the beginning of the differences between Mysql and SQLite
Provide some query examples and we may be able to assist you with each one.
-- update after your addition of query code...
Here is an example of sqlite-nodejs
const sqlite3 = require('sqlite3').verbose();
// open the database
let db = new sqlite3.Database('./db/chinook.db');
let sql = `SELECT * FROM users WHERE LOWER(username) = LOWER(?)`;
db.all(sql, [req.body.username], (err, rows) => {
if (err) {
throw err;
}
rows.forEach((row) => {
console.log(row.name);
});
});
// close the database connection
db.close();
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.
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 have a function to retrieve a list of UserID's from a mysql database.
function GetUsers(callback) {
UpdateLogFile('Function Call: GetUsers()')
var users = []
Database.execute( connectionStr,
database => database.query('select UserID from Users')
.then( rows => {
for (let i = 0; i < rows.length; i++){
users.push(rows[i].UserID)
}
return callback(users)
})
).catch( err => {
console.log(err)
})
}
For Reference:
Database class which came from here
const mysql = require( 'mysql' )
class Database {
constructor( config ) {
this.connection = mysql.createConnection( config )
}
query( sql, args ) {
return new Promise( ( resolve, reject ) => {
this.connection.query( sql, args, ( err, rows ) => {
if ( err )
return reject( err )
resolve( rows )
})
})
}
close() {
return new Promise( ( resolve, reject ) => {
this.connection.end( err => {
if ( err )
return reject( err )
resolve()
})
})
}
}
Database.execute = function( config, callback ) {
const database = new Database( config )
return callback( database ).then(
result => database.close().then( () => result ),
err => database.close().then( () => { throw err } )
)
}
After hours of learning about promises and callbacks, I was finally able to get GetUsers() to at least work and return what I'm looking for. However, I seem to only be able to use it as such:
GetUsers(function(result){
// Do something with result
})
But I would really like to be able to have a traditional return statement in the function so that I could use it like this: var users = GetUsers(). I have seen posts saying that this is impossible due to the nature of asynchronous functions but I am still hopeful since I would really like to be able to avoid callback hell. I tried the code below but "users" just results as undefined after execution. So, my main goal is to be able to get the return value from GetUsers() without chaining callbacks together since I have other functions that behave similarly. Is this possible?
var users
GetUsers(function(result){
users = result
})
console.log(users)
This is a very confusing topic, and it took me a while to really understand why what you are asking simply is not possible (at least, in the exact way you are asking). For the examples I will using python Django and Node.js to compare.
Sync
def synchronous():
print('foo') //this will always print first
print('bar')
def getUsers():
with connection.cursor() as cursor:
cursor.execute('SELECT * FROM USERS') //this query is executed
users = cursor.fetchall()
print('foo') //this doesn't trigger until your server gets a response from the db, and users is defined
print(users)
Async
function asynchronous() {
console.log('foo'); //this will also always print first
console.log('bar');
}
function getUsers() {
var connection = mysql.createConnection(config);
connection.query('SELECT * FROM USERS', function(error, users) { //this is a "callback"
console.log(users); //this will print
//everything inside of here will be postponed until your server gets a response from the db
});
console.log('foo') //this will print before the console.log above
console.log(users); //this will print undefined
//this is executed before the query results are in and will be undefined since the "users" object doesn't exist yet.
}
A callback is simply the function that your server is supposed to run once you get a response. We typically use the actual word "callback" like this:
function getUsers(callback) {
var connection = mysql.createConnection(config);
connection.query('SELECT * FROM USERS', function(error, users) {
if (error) throw error; //always do your error handling on the same page as your query. Its much cleaner that way
callback(users) //server asks what to do with the "users" object you requested
});
}
Now on somewhere else on your server:
getUsers(function(users) {// the callback gets called here
console.log(users); //do what you want with users here
});
The getUsers function takes some other function (ie a callback) as its argument and executes that function after you perform your query. If you want to do the same thing without using the word "callback", you can use an await/async function like fsociety, or you explicitly write out your code and not make functions that take other functions as their arguments.
This is functionality identical to the code from above:
var connection = mysql.createConnection(config);
connection.query('SELECT * FROM USERS', function(error, users) {
if (error) throw error;
console.log(users);
});
Callback hell is inevitable, but it really Isn't too bad once you get the hang of it.
Use an async-await function instead.
async function GetUsers(callback) {
try {
UpdateLogFile('Function Call: GetUsers()')
var users = []
let rows = await Database.execute( connectionStr,
database => database.query('select UserID from Users')
for (let i = 0; i < rows.length; i++){
users.push(rows[i].UserID)
}
return callback(users)
} catch(err) {
console.log(err)
}
}
Hope this helps!
Here is my efforts :
async.waterfall([
function(nextCall){
MongoClient.connect(url, function(err, db) {
if (err) throw err;
const dbo = db.db("testmdb");
const criteria = {"_id":ObjectId(id)};
console.log("paymentInof[] ::: ",paymentInfo)
let obj = paymentInfo[0];
const query = {
$push:{payment:obj}
};
dbo.collection("Invoice").update(criteria, query);
db.close();
nextCall(null,{code:200});
});
}
],function(err,results){
if(err) return err;
if(results.code === 200)
console.log(chalk.blue(' ::: all done ::: '));
next();
});
Input from api explorer :
{
"payment":[{"transaction_at":"2018-02-12T06:04:35.279Z","paid_amount":350,"patient_id":"1233sssdd33","patient_urn":"214125","invoice_amount":700,"user":"me"}],
"updated_by": "me"
}
Everything working fine but unable to push instead overwriting the existing object in payment array.
While from mongo shell it is working fine.
Please help me , where I am doing wrong ?
Thanks.
I think you need to check mongoose update upsert option.
Update options
There are several option values that can be used with an update
multi - update all records that match the query object, default is false (only the first one found is updated)
upsert - if true and no records match the query, insert update as a new record
raw - driver returns updated document as bson binary Buffer, default:false
Please check the documentation to here.
Use following code,
async.waterfall([
function(nextCall){
MongoClient.connect(url, function(err, db) {
if (err) throw err;
const dbo = db.db("testmdb");
let criteria = {"_id": ObjectId(id)};
let obj = paymentInfo[0];
let query = { $push: { payment: obj } }
dbo.collection("Invoice").update(criteria, query, {upsert:true});
db.close();
nextCall(null,{code:200});
});
}
],function(err,results){
if(err) return err;
if(results.code === 200)
console.log(chalk.blue(' ::: all done ::: '));
next();
});
Also please check the similar type of question to here and here.
Hope this will help you!!