CODEWITHSUNDEEP
node.jsasync-await
Mukund
Mukund

Reputation: 1105

What is the best way to handle nodejs database async functions

I want a suggestion on how to perform nodejs-DB operations

Here are my options

case one : When you have to run more than one query and former one is dependent on the latter

first way

    connection.query(Q1, function(error, results, fields) {
        if (error) {
            throw error;
        }
        console.log(results[0]);
 //call the second query here
        connection.query(Q2, function(error, results, fields) {
        if (error) {
            throw error;
        }
        console.log(results[0]);


    });
    });

or

define first query in a function return the result via promise and await function

call the second query in the same way

use both results

like 

var res1 = await funcName1(params);
var res2 = await funcName2(params);// params deducted from res1

which one is better?

case two : when we want to call select query more than 1 times

and capture the results in an array

the last one is pretty preplexing, do i have to call the mysql async function in a loop? is it a correct way?

Can you guys redirect me in the correct way?

Upvotes: 0

Views: 109

Answers (1)

Terry Lennox
Terry Lennox

Reputation: 30675

I would suggest using the second option, or rather a similar approach to the second option. I believe the code is much easier to read and simpler to maintain. You'll also end up with a fraction of the number of lines of code.

It's also worth nothing that many database modules such as mysql2 and mongodb return promises directly, so there's no need to create wrapper functions, that is you won't need to maintain a load of funcName1, funcName2.. etc.

for example using mysql2:

const mysql = require('mysql2/promise');
const connection = await mysql.createConnection({
    host: 'localhost',
    user: 'some_user',
    password: '***',
    database: 'test_db'
});

let [users] = await connection.query('select * from users');
let [accounts] = await connection.query('select * from accounts');

console.log( { users, accounts })

If you wish to create promisified wrapper functions for a generic db access proc, have a look at Util.promisify, this allows you to cut down on boilerplate code.

e.g.

const dbQuery = util.promisify(db.query);

Then you can use like

let result = await dbQuery(param1, param2...);

As long as db.query looks something like

db.query(query, callback(err, result))

Also, querying within loops should work very well, for example:

async function testLoopQuery() {
    for(let organization of organizationList) {
        let [users] = await connection.query('select * from users where org_id = ?', [organization.id]);
    }
}

Upvotes: 1

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