Make my db queries synchronous with with my promise based function - node.js

Question

How can I make my db queries synchronous with with my promise base function? In my code, I am running 3 db operations inside 3 different functions which need to be run in order, like waterfall model. The functions are running in waterfall model but db queries inside those functions are working in asynchronous. I need to run db queries inside those function in synchronous.
In this example I am expecting in console:
1
2
3
4
But I am getting
1
3
2
4
Code:
const Promise = require('bluebird');
// DB Settings
const dbConfig = {
user: process.env.DBUSER,
password: process.env.DBPWD,
database: process.env.DBNAME,
host: process.env.DBHOST,
port: process.env.DBPORT,
poolSize: 10, // max number of clients in the pool
//poolIdleTimeout: 30000, // how long a client is allowed to remain idle before being closed
//reapIntervalMillis: 1000 //frequency to check for idle clients within the client pool
};
const pgp = require('pg-promise')();
const db = pgp(dbConfig);
var currentStatus = '',newStatus = '';
const _updateCurrentStatus = () => new Promise((resolve, reject) => {
const _getCurrentStatus = (_userId) => new Promise((_resolve, _reject) => {
console.log("1");
let statusQuery = "SELECT status FROM users WHERE id=" + _userId;
db.one(statusQuery).then(function (data) {
console.log("2");
currentStatus = data.status;
_resolve();
}).catch(function (error) {
_reject(error);
});
});
const _setUpdateStatus = (cStatus, nStatus) => new Promise((_resolve, _reject) => {
if(allApproved){
if(cStatus == 'nvd_pending'){
//nStatus = 'finance_pending';
newStatus = 'finance_pending';
}else if(cStatus == 'finance_pending'){
//nStatus = 'oracle_pending';
newStatus = 'oracle_pending';
}else if(cStatus == 'oracle_pending'){
//nStatus = 'active';
newStatus = 'active';
}else{
//nStatus = cStatus;
newStatus = cStatus;
}
}else{
//nStatus = 'nvd_pending';
newStatus = 'nvd_pending';
}
//_resolve(nStatus);
_resolve();
});
const _updateStatus = (_newStatus, _payLoad) => new Promise((_resolve, _reject) => {
console.log("3");
let updateuserQuery = "UPDATE users SET status = '"+ _newStatus + "' WHERE id=" + _payLoad.user_id;
let updatePanQuery = "UPDATE user_documents SET status = '" + _payLoad.panstatus + "' WHERE id= " + _payLoad.panid + " AND user_id=" + _payLoad.user_id;
let updateFinanceQuery = "UPDATE user_finance_details SET status = '" + _payLoad.financestatus +" 'WHERE id= " + _payLoad.financeid + " AND user_id=" + _payLoad.user_id;
db.tx(function (t) {
console.log("4");
// `t` and `this` here are the same;
// this.ctx = transaction config + state context;
return t.batch([
t.none(updateuserQuery),
t.none(updatePanQuery),
t.none(updateFinanceQuery)
]);
}).then(function (data) {
_resolve(data);
}).catch(function (error) {
_reject(error);
});
});
_getCurrentStatus(payLoad.user_id)
.then(_setUpdateStatus)
.then( _updateStatus(newStatus, payLoad))
.then( values => {
resolve(values);
},error => {
reject(error);
})
.catch((error) => reject(error));
});

Answer 1

You are overcomplicating thing here. First feedback is that you don't need those new Promise wrappers, since pg-promise is already creating promises. You can greatly flatten things here:
function getCurrentStatus(userId) {
console.log("1");
let statusQuery = "SELECT status FROM users WHERE id=" + userId;
return db.one(statusQuery).then(function (data) {
console.log("2");
return data.status;
});
}
function getUpdatedStatus(cStatus)
console.log('2');
if (allApproved) {
if(cStatus == 'nvd_pending'){
newStatus = 'finance_pending';
} else if (cStatus == 'finance_pending'){
newStatus = 'oracle_pending';
} else if (cStatus == 'oracle_pending'){
newStatus = 'active';
} else {
newStatus = cStatus;
}
} else {
newStatus = 'nvd_pending';
}
return newStatus;
}
function updateStatus(newStatus, payLoad) {
console.log("3");
let updateuserQuery = "UPDATE users SET status = '"+ newStatus + "' WHERE id=" + payLoad.user_id;
let updatePanQuery = "UPDATE user_documents SET status = '" + payLoad.panstatus + "' WHERE id= " + payLoad.panid + " AND user_id=" + payLoad.user_id;
let updateFinanceQuery = "UPDATE user_finance_details SET status = '" + payLoad.financestatus +" 'WHERE id= " + payLoad.financeid + " AND user_id=" + payLoad.user_id;
return db.tx(function (t) {
console.log("4");
// `t` and `this` here are the same;
// this.ctx = transaction config + state context;
return t.batch([
t.none(updateuserQuery),
t.none(updatePanQuery),
t.none(updateFinanceQuery)
]);
});
});
function updateCurrentStatus(payLoad) {
return getCurrentStatus(payLoad.user_id)
.then(cStatus => getUpdatedStatus(cStatus))
.then(newStatus => updateStatus(newStatus, payLoad));
}
The specific reason you're seeing 3 out of order is because you're calling it immediately via _updateStatus(newStatus, payLoad) instead of wrapping it in a function (see my suggested code updates above).