I want to add have nested DB query inside a eachOf loop which should be synchronous. Tried so many combinations and which but nothing works for inside of foreach loop.
async.eachOf(nc.virtual_devices, function (vd) {
///////// This code work fine /////////////
var domain = extractDomain(vd.api_url);
vd.raw_api_ip = vd.api_ip;
vd.api_ip = getProxiedPath(vd.api_ip);
vd.raw_api_url = vd.api_url;
vd.api_url = nconf.get('PROXIED_PATH_SCHEME') + vd.api_ip + vd.api_url.split(domain)[1];
// Path to websocket notifications
vd.ws_url = nconf.get('PROXIED_PATH_SCHEME') + vd.api_ip + vd.notification_base_uri;
//// THIS CODE IS NOT FINE //////////////
if (nc.type === 'XXX'){
var promise = new Promise (function (resolve,reject) {
console.log("********XX VD TYPE **********");
console.log(JSON.stringify(vd));
console.log("VD ID VALUE IS ", vd.id);
var newID = (vd.id).replace(/\d_/, "");
console.log("VD ID VALUE IS ", newID);
var _idofSubgroup;
var labeltoSearch = nc.type + ' ' + nc.version;
pattern = "/^" + newID + "/i";
test = _idofSubgroup;
pattern = newID;
console.log(pattern);
db.collection('subgroups').findOne({label: labeltoSearch}, function (err, result) {
console.log(result._id);
_idofSubgroup = result._id;
db.collection('exploreposts').find({subgroup: result.id_}, {title: {"$regex": pattern}}).toArray(function (err, results) {
console.log(results);
})
});
})
}
});
Tried with promise inside it but that also in pain. This is my tried code which is not working fine. Any suggestion would be appreciated., as simply said i have been stuck in callback hell
async.eachOf(nc.virtual_devices, function (vd) {
///////// This code work fine /////////////
var domain = extractDomain(vd.api_url);
vd.raw_api_ip = vd.api_ip;
vd.api_ip = getProxiedPath(vd.api_ip);
vd.raw_api_url = vd.api_url;
vd.api_url = nconf.get('PROXIED_PATH_SCHEME') + vd.api_ip + vd.api_url.split(domain)[1];
// Path to websocket notifications
vd.ws_url = nconf.get('PROXIED_PATH_SCHEME') + vd.api_ip + vd.notification_base_uri;
//// THIS CODE IS NOT FINE with promises also //////////////
if (nc.type === 'XXX'){
var promise = new Promise (function (resolve,reject) {
console.log("********XX VD TYPE **********");
console.log(JSON.stringify(vd));
console.log("VD ID VALUE IS ", vd.id);
var newID = (vd.id).replace(/\d_/, "");
console.log("VD ID VALUE IS ", newID);
var _idofSubgroup;
var labeltoSearch = nc.type + ' ' + nc.version;
pattern = "/^" + newID + "/i";
test = _idofSubgroup;
pattern = newID;
console.log(pattern);
db.collection('subgroups').findOne({label: labeltoSearch}, function (err, result) {
console.log(result._id);
_idofSubgroup = result._id;
resolve ({id_:_idofSubgroup,pattern1 : pattern});
})
});
promise.then (function(result) {
console.log(result.id_);
console.log(result.pattern1);
db.collection('exploreposts').find({subgroup: result.id_}, {title: {"$regex": result.pattern1}}).toArray(function (err, results) {
console.log(results);
})
},function (err){
console.log (err);
})
}
});
It doesn't seem you need to use async.eachOf, but async.each() or async.eachSeries().
This is untested but it would look something like
async.eachSeries(nc.virtual_devices, function iteratee(vd, cb) {
console.log('calling iteratee()')
var domain = extractDomain(vd.api_url);
vd.raw_api_ip = vd.api_ip;
vd.api_ip = getProxiedPath(vd.api_ip);
vd.raw_api_url = vd.api_url;
vd.api_url = nconf.get('PROXIED_PATH_SCHEME') + vd.api_ip + vd.api_url.split(domain)[1];
// Path to websocket notifications
vd.ws_url = nconf.get('PROXIED_PATH_SCHEME') + vd.api_ip + vd.notification_base_uri;
// skip the rest if type is XXX;
// you need to explicitedly call the original callback i.e. cb
// note the use of return to prevent execution of the rest of the code
if (nc.type !== 'XXX')
return cb(null); // or cb();
console.log("********XX VD TYPE **********");
console.log(JSON.stringify(vd));
console.log("VD ID VALUE IS ", vd.id);
var newID = (vd.id).replace(/\d_/, "");
console.log("VD ID VALUE IS ", newID);
// I have no idea what is going here
var _idofSubgroup;
var labeltoSearch = nc.type + ' ' + nc.version;
var pattern = "/^" + newID + "/i";
test = _idofSubgroup;
pattern = newID;
console.log(pattern);
// we're going to use waterfall here as you have 2 async operations, where one is dependent on the other
async.waterfall([
function getSubgroup(cb1) {
console.log('calling getSubgroup')
db.collection('subgroups').findOne({ label: labeltoSearch }, function (err, subgroup) {
// if an error occurs, stop waterfall-loop
// you do this by passing the error in the callback
// again note the use of return here to prevent execution of the rest of the code
if (err) return cb1(err);
// pass the data to the next task
cb1(null, subgroup, pattern);
});
},
function getPosts(subgroup, pattern, cb2) {
// we will only get here if the last task ^ went through
console.log('calling getPosts')
db.collection('exploreposts').find({ subgroup: subgroup._id, title: { $regex: pattern }}).toArray(function (err, posts) {
// if an error occurs, stop waterfall-loop
if (err) return cb2(err);
// do something with posts
console.log('posts', posts);
// otherwise, keep going
// since there are no more waterfall-tasks, waterfall ends
cb2();
});
}
], function (err) {
console.log('waterfall() done');
// if an error occurred during the waterfall-loop, it will come down here
// we will let the original callback i.e. cb deal with this error though
if (err) return cb(err);
// otherwise we're done
// we will let the original callback know everything went well by calling it without any error
cb();
});
// you could have also simply do
// ], cb);
}, function (err) {
console.log('eachSeries() done');
// handle any error that came
console.log(err);
// send response
});
I purposely name the variables and functions so that you get an idea.
Follow the logs if there are any issues.