I use Async utility module in my app. I have a question. How i can restart the async.series, when "get_data" stage return an error?
function get() {
console.log('App start');
async.series([
open_db,
get_data,
close_db
], function (err) {
console.log('App down');
})
};
function open_db(callback) {
mongoose.connect('mongodb://localhost/app', function (err) {
if (err) throw err;
console.log('App connect to DB');
callback();
});
};
function get_data(callback) {
if (err) {
console.log('Error')
callback();
} else {
console.log('Ok');
callback();
}
};
function close_db(callback) {
mongoose.disconnect(function() {
console.log('App disconnect from DB');
callback();
});
};
On "get_data" stage i use websockets.subscribe operations, and save data from another server to DB. When websocket connection down, i need to retry connection to server with some time interval
function query_data() {
async.series([
open_db,
get_data,
close_db
], function (err) {
if (err)
...
})
};
function open_db(callback, attempt_no) {
mongoose.connect('mongodb://localhost/app', function(err) {
if (!err)
return callback();
attemp_no = !attempt_no ? 1 : attempt_no + 1;
if (attempt_no > 5)
return callback(new Error('Maximum number of attempts exceeded'));
setTimeout(() => open_db(callback, attempt_no), 500);
});
};
function get_data(callback) {
if (err)
return callback(err);
// do-smth-with-data and call callback
};
function close_db(callback) {
mongoose.disconnect(callback);
};
Use async.retry
function all_get_data(cb) {
console.log('App start');
async.series([
open_db,
get_data,
close_db
], function (err) {
if (err) {
console.log('App down');
return cb(err)
}
return cb()
})
};
// try calling apiMethod 3 times, waiting 200 ms between each retry
async.retry({times: 3, interval: 200}, all_get_data, function(err, result) {
// do something with the result
});
Related
I am using async parallel to get data from db in parallel.
When every task is returning the data I am storing it in local object.
From index.js I am calling cacheService.js .
In cacheService.js I am loading data from mysql database and mongo database in to cache object.
Whenever I am doing npm run local run. I am getting following error.
UNHANDLEDREJECTION Error: Callback was already called.
This error is coming from loadMongoData method of cacheService.js.
I have followed other answers on stackoverflow like adding else part
Here is code for cacheService.js.
'use strict';
var cache = [];
class cacheService {
async init() {
await this.loadMongoData();
}
loadMongoData(env, callback1) {
const _this = this;
console.log('Inside loadMongoData')
async.parallel(
{
task1: function (callback) {
CriteriaDef.find({})
.lean()
.exec(function (err, criteriaDefs) {
if (err) {
console.log('Inside err 1')
logger.error('Error fetching CriteriaDef: ', util.inspect(err));
callback(err, null);
} else if (criteriaDefs) {
console.log('Inside criteriaDefs')
if (criteriaDefs.length && criteriaDefs.length > 0) {
console.log('Inside criteriaDefs 1')
global.CRITERIA_DEFS = criteriaDefs;
cache['criteria_defs'] = criteriaDefs;
}
callback(null, null);
}
});
},
task2: function (callback) {
groupDef
.find({})
.lean()
.exec(function (err, groupDefs) {
if (err) {
console.log('Inside err2')
logger.error('Error fetching groupDefs: ', util.inspect(err));
callback(null, err);
} else if (groupDefs) {
console.log('Inside ')
global.groupDefsWithRoles = groupDefs;
let _groupDefs = [];
_.each(groupDefs, function (groupDef) {
var data = {
value: groupDef._id,
label: `${groupDef._id}: ${groupDef.description}`
};
_groupDefs.push(data);
});
global.groupDefs = _groupDefs;
cache['groupDefs'] = _groupDefs;
logger.info('Loaded groupDefs: ', global.groupDefs.length);
callback(null, null);
}
});
},
task3: function (callback) {
jiraProjects.find({$or: [{archived: {$ne: true}}, {archived: {$exists: false}}]}).exec(function (err, jiraProjects) {
if (err) {
console.log('Inside error 3')
logger.error('Error fetching jiraProjects: ', err);
callback(null, err);
} else if (jiraProjects) {
console.log('Inside jira project')
let _jiraProjects = [];
_.each(jiraProjects, function (jiraProject) {
var data = {
value: jiraProject.key,
label: jiraProject.key,
issueType: jiraProject.issueType ? jiraProject.issueType : 'Bug'
};
_jiraProjects.push(data);
});
global.jiraProjectsList = _jiraProjects;
cache['jiraProjects'] = _jiraProjects;
logger.info('Loaded jira projects: ', global.jiraProjectsList.length);
callback(null, null);
}
});
},
task4: function (callback) {
console.log('Inside task4')
callback(null, null);
},
task5: function (callback) {
inputElements
.find({})
.lean()
.exec(function (err, inputElements) {
if (err) {
console.log('Inside error5')
logger.error('Error fetching inputElements: ', util.inspect(err));
callback(null, err);
} else if (inputElements) {
console.log('Inside inputelements')
global.INPUT_ELEMENTS_DEF = inputElements;
cache['INPUT_ELEMENTS_DEF'] = inputElements;
callback(null, null);
}
});
},
task6: function (callback) {
console.log('Inside task6')
sisp.loadProducts('', callback);
}
},
function (err, results) {
if (err) {
console.log('Inside final error')
logger.error("Something went wrong can't start the app: ", util.inspect(err));
callback1(null, err);
} else {
console.log('Inside final else')
logger.info('loaded all globals properly :)');
callback1(null, null);
}
}
)
}
}
export default new cacheService();
I think your problem cuz you use callback inside of promise.
Please change your code like this:
class cacheService {
async init() {
await new Promise((resolve, reject) => {
this.loadMongoData(env, (ignoreArg, error) => {
if (error) {
return reject(error);
}
resolve();
});
});
}
...
}
Tip: in the each task add statement else for call callback, because maybe your statement not handled and your code can't execute prefect
task1: function (callback) {
CriteriaDef.find({})
.lean()
.exec(function (err, criteriaDefs) {
if (err) {
console.log('Inside err 1')
logger.error('Error fetching CriteriaDef: ', util.inspect(err));
callback(err, null);
} else if (criteriaDefs) {
console.log('Inside criteriaDefs')
if (criteriaDefs.length && criteriaDefs.length > 0) {
console.log('Inside criteriaDefs 1')
global.CRITERIA_DEFS = criteriaDefs;
cache['criteria_defs'] = criteriaDefs;
}
callback(null, null);
} else {
callback(null, null);
}
});
},
Can someone explain me below code snippet? Here how and when .on method with tags "error" and "close" executes when it is not emitted anywhere.
function start() {
amqp.connect(process.env.CLOUDAMQP_URL + "?heartbeat=60", function(err, conn) {
if (err) {
console.error("[AMQP]", err.message);
return setTimeout(start, 1000);
}
conn.on("error", function(err) {
if (err.message !== "Connection closing") {
console.error("[AMQP] conn error", err.message);
}
});
conn.on("close", function() {
console.error("[AMQP] reconnecting");
return setTimeout(start, 1000);
});
console.log("[AMQP] connected");
amqpConn = conn;
whenConnected();
});
}
Bit new to node.js and javascript. Attempting to have my foreach call a function that in turn does a remote call. I'd like there to be a delay between each but can't seem to work out where to put the set timeout.
I know I have my setTimeout in the wrong place below but putting it in there as an example.
var likeRecommendation = function (recommendation, callback) {
context.Client.like(recommendation._id, function (error, data) {
recommendation['drupal_user_uid'] = context.message.uid;
recommendation['drupal_user_uuid'] = context.message.uuid;
if (error) return callback(new Error('Could not like recommendations'));
context.broker.publish('saves_swipes_publication', recommendation, function (err, publication) {
if (err) return callback(new Error('Could queue swipes to save'));
publication.on('error', console.error);
});
console.log('Liked!');
return callback()
});
}
async.forEach(context.recommendations, likeRecommendation, function (error) {
if (!error) return done(null);
done(new Error('Could not like recommendations'));
});
}
See timeout, warning one of your callback was missing and one other was not well placed.
var likeRecommendation = function (recommendation, callback) {
context.Client.like(recommendation._id, function (error, data) {
recommendation['drupal_user_uid'] = context.message.uid;
recommendation['drupal_user_uuid'] = context.message.uuid;
if (error)
setTimeout(function(){return callback(new Error('Could not like recommendations'))}, 100);
else {
context.broker.publish('saves_swipes_publication', recommendation, function (err, publication) {
if (err)
setTimeout(function(){return callback(new Error('Could queue swipes to save'))}, 100);
else
{
publication.on('error', console.error);
setTimeout(function(){ return callback();}, 100);
}
});
}
});
}
async.forEach(context.recommendations, likeRecommendation, function (error) {
if (!error) return done(null);
done(new Error('Could not like recommendations'));
});
}
The setTimeout will have to be placed at the end of the callback code.
Here is a possible solution (note that it doesn't use async.forEach)
var likeRecommendation = function (recommendation, callback) {
context.Client.like(recommendation._id, function (error, data) {
recommendation['drupal_user_uid'] = context.message.uid;
recommendation['drupal_user_uuid'] = context.message.uuid;
console.log(recommendation);
if (error) return done(new Error('Could not like recommendations'));
context.broker.publish('saves_swipes_publication', recommendation, function (err, publication) {
if (err) throw err
publication.on('error', console.error);
});
console.log('Liked!');
return callback()
});
}
function iterateWithTimeout(list, ctx, timeoutDuration) {
var currentIndex = 0;
(function invoke() {
list[currentIndex](ctx, function(error) {
if (!error) return done(null);
done(new Error('Could not like recommendations'));
setTimeout(function() {
if (++currentIndex < list.length) {
invoke();
}
}, timeoutDuration);
});
})();
}
// Interval is 1 second for now
iterateWithTimeout(context.recommendations, likeRecommendation, 1000);
So using "async.eachSeries" rather than "async.forEach" was the solution!
As always thanks for the help!
Pretty sure this is a quite noobish node.js/callback question but I can't seem to find the proper code to make it run.
This is how I invoke my node-mysql code:
var utils = require('../../config/database/utils');
exports.getResults = function(callback) {
var query = "SELECT * FROM my_table";
utils.exec(query, null, function(err, results){
if(err){
console.log(err);
callback(true);
return;
}
console.log(results);
callback(false, results);
});
};
Next is the utils file where I can't get the code work.
var pool = require('./connection');
module.exports = {
getDBConnection: function() {
pool.getConnection(function(err, connection){
if(err){
console.log(err);
return;
}
return connection;
});
},
endDBConnection: function(connection) {
connection.end(function (err) {
if(err) {
console.log(err);
callback(true);
return;
}
});
},
exec: function(query, data, callback) {
console.log(query);
this.getDBConnection(function(err, connection){
if(err){
console.log('error');
}
console.log(connection);
connection.query(query, data, function(err, results) {
if(err) {
callback(err);
}
callback(false, results);
});
this.endDBConnection(connection);
});
}
}
Code is getting OK the the exec part since the console.log(query) logs the query. But after that, the code's not running, console.log(connection); doesn't show a thing, and of course the connection.query is also not running.
I'm not sure why this is happening.
Returning a value inside a callback is meaningless. You need to pass in a callback that gets called with the value you want to return:
getDBConnection: function(callback) {
pool.getConnection(function(err, connection){
if(err){
console.log(err);
return callback(err);
}
callback(null, connection);
});
},
You should also use connection.release() instead of connection.end() since you are using a pool:
endDBConnection: function(connection) {
connection.release();
},
In exec(), you have the wrong this. It should instead be something like:
exec: function(query, data, callback) {
console.log(query);
var self = this;
this.getDBConnection(function(err, connection){
if(err){
console.log('error');
return callback(err);
}
console.log(connection);
connection.query(query, data, function(err, results) {
self.endDBConnection(connection);
if(err) {
return callback(err);
}
callback(null, results);
});
});
}
How do I get the return value from inside a value of node.js/javascript callback?
function get_logs(){
User_Log.findOne({userId:req.user._id}, function(err, userlogs){
if(err) throw err;
if(userlogs){
// logs = userlogs.logs;
return "hello there is a logs";
} else {
return "there is no logs yet..."
}
})
}
var logs = get_logs();
console.log(logs);
You can't return the result from a function whose execution is asynchronous.
The simplest solution is to pass a callback :
function get_logs(cb){
User_Log.findOne({userId:req.user._id}, function(err, userlogs){
if(err) throw err;
if(userlogs){
// logs = userlogs.logs;
cb("hello there is a logs");
} else {
cb("there is no logs yet...)"
}
})
}
get_logs(function(logs){
console.log(logs);
});
You can't. You should instead pass another callback to your function. Something like this:
function get_logs(callback){
User_Log.findOne({userId:req.user._id}, function(err, userlogs){
if(err) throw err;
if(userlogs){
callback("hello there is a logs");
} else {
callback("there is no logs yet...");
}
})
}
get_logs(function(arg1) {
console.log(arg1);
});
function get_logs(callback) {
User_Log.findOne({
userId: req.user._id
}, function (err, userlogs) {
if (err) throw err;
if (userlogs) {
// logs = userlogs.logs;
callback("hello there is a logs");
} else {
callback("there is no logs yet...");
}
})
}
get_logs(function (data) {
console.log(data);
});
Uses callbacks...
In node.js almost all the callbacks run after the function returns , so you can do something like this
function get_logs(){
User_Log.findOne({userId:req.user._id}, function(err, userlogs){
if(err) throw err;
if(userlogs){
// logs = userlogs.logs;
do_something(logs)
} else {
console.log('No logs')
}
})
}