I’m trying to make several inserts in database from an array but … I have a problem with de connection and disconnection to the database
For example, with this code, I only insert the first element and then I’ve got an error because the access to the database has been disconnected.
async function saveData(destinations){
let ddbb = new PostgresqlDDBB();
ddbb.connect();
await destinations.forEach(async (country, index) => {
let params = [country.countryName, country.countryCode, country.urlProperties];
let id = await ddbb.insertData(2, params);
destinations[index].id = id;
});
ddbb.disconnect()
}
The object PostgresqlDDBB has this code:
import {Result} from "../../com/result";
import {clientPG} from "./pg_connection";
import {selectQuery} from "../queries/pg_queries";
class PostgresqlDDBB{
constructor(){
this.query = null;
}
set query(id){
this.__query = selectQuery(id);
}
get query(){
return this.__query;
}
async connect(){
await clientPG.connect();
}
disconnect(){
clientPG.end();
}
/**
*
* @param {*} id_query ID of query to run
* @param {*} params params to pass to the query
* @returns The last id save in the database
*/
async insertData(id_query, params){
let result;
try{
let query = selectQuery(id_query);
if (params !== null)
result = await clientPG.query(query, params);
else
result = await clientPG.query(query);
return result.rows[0].id;
}catch(err){
console.log(err.stack);
}
}
}
module.exports.PostgresqlDDBB = PostgresqlDDBB;
And the client of Postgress has this code:
import {Client} from "pg";
import config from "../../config";
const clientPG = new Client({
user: config.db_postgres.user,
password: config.db_postgres.password,
database: config.db_postgres.name,
host: config.db_postgres.host,
//ssl: config.db_postgres.ssl
});
module.exports.clientPG = clientPG;
Looking for the code of saveData I don’t knwo why forEach don’t wait to finish the insert of all elements.
If I do the same instead of a forEach with a for and call the function twice:
async function saveData(destinations){
let ddbb = new PostgresqlDDBB();
await ddbb.connect();
for(let i = 0; i < destinations.length; i++){
let country = destinations[i];
let params = [country.countryName, country.countryCode, country.urlProperties];
let id = await ddbb.insertData(2, params);
}
ddbb.disconnect();
console.log("Voy a salir!!!");
};
saveData(list);
saveData(list);
The first time works fine but the second time we’ve got this error:
Voy a salir!!!
/home/josecarlos/Workspace/BlueCode/Youmalou/mapping-service/node_modules/pg/lib/client.js:94
const err = new Error('Client has already been connected. You cannot reuse a client.')
^
Error: Client has already been connected. You cannot reuse a client.
The second time we run the function the connection is still open. How is that possible?
What is the best moment to open the connection? Is a good practive to open the connection and not close it because when the object will be deleted the connection too?
How can I open, insert data, close the connection, open connection again, insert data, close the connection etc.?
Am I doing something wrong?
