pass argument to mysql connection string - node.js

Question

Below is my code (under file db.js)
function connection() {
try {
const mysql = require('mysql2');
const pool = mysql.createPool({
host: "mydb.abcd1234.ap-southeast-1.rds.amazonaws.com",
database: "mydatabase",
user: "user",
password: "password",
connectionLimit: 11,
waitForConnections: true,
queueLimit: 0,
namedPlaceholders: true
});
const promisePool = pool.promise();
return promisePool;
} catch (error) {
return console.log(`Could not connect - ${error}`);
}
}
const pool = connection();
module.exports = {
connection: async () => pool.getConnection(),
execute: (...params) => pool.execute(...params)
};
And to use it, I simply add var db = require('./../db.js'); at the top of the files that requires it. Additionally, below is how I'd execute any sql statements
const myResult = await db.execute("Select COUNT(*) AS dataCount from teachers WHERE username = ?", [username]);
But now I need to separate my database according to countries. So my database would be named with mydatabase_ + the country code, for example mydatabase_my , mydatabase_jp, mydatabase_uk etc etc. So how do I pass the country code to the function connection() ?
I tried something like
function connection(country) {
try {
const mysql = require('mysql2');
const pool = mysql.createPool({
host: "mydb.abcd1234.ap-southeast-1.rds.amazonaws.com",
database: "mydatabase_" + country,
user: "user",
password: "password",
connectionLimit: 11,
waitForConnections: true,
queueLimit: 0,
namedPlaceholders: true
});
const promisePool = pool.promise();
return promisePool;
} catch (error) {
return console.log(`Could not connect - ${error}`);
}
}
const pool = connection(country);
module.exports = {
connection: async (country) => pool.getConnection(country),
execute: (...params) => pool.execute(...params)
};
and at the calling page, I did
var db = require('./../db.js');
db.connection("my")
but for the above, I will get ReferenceError: country is not defined which refers to country at the line const pool = connection(country);

Answer 1

Here's how I did it:
const mysql = require('mysql2');
const pool = function(country){
var mydb = mysql.createPool({
host: "mydb.abcd1234.ap-southeast-1.rds.amazonaws.com",
database: "mydatabase_" + country,
user: "user",
password: "password",
connectionLimit: 11,
waitForConnections: true,
queueLimit: 0,
namedPlaceholders: true
});
return mydb;
}
const promisePool = function(country){
return pool(country).promise();
}
module.exports = {
connection: async (country) => promisePool(country).getConnection(),
execute: (country,...params) => promisePool(country).execute(...params)
};
And in the page that uses mysql will have something like this:
db.connection(country)
const myResult = await db.execute(country, "Select * from schools");