I am writing an service, where I retrieve a list of items from a another service, then iterate over result performing keystone.list operation(s).
I am loosing the return status in the find/exec operation. I have tried promises, async, etc.
If someone could point out the correct way to implement this, I would appreciate it.
general implementation:
exports = module.exports = function (req, res) {
var rtn = {
added: 0,
count: 0
}
service(params)
.then(function(svcResult) {
svcResult.forEach(function(item) {
rtn.count++; // <-- correctly seen in apiresponse
Artifact.model.find()
.where({ artifactId: item.id})
.exec(function(err, result) {
if (result.length == 0) {
result = new Artifact.model({
... populate from item ....
});
result.save();
rtn.added++; // <-- not seen in api response
});
});
res.apiResponse(rtn);
});
}
for starters, exec is an async call, which you are ignoring in your res.apiResponse and thus count is incremented and not added, to make life easy, I am moving the exec call outside and wrapping it with promise:
function pExec(id){
return new Promise(function(resolve, reject){
Artifact.model.find()
.where({ artifactId: id})
.exec(function(err, result){
console.log('result: ', result); // there is a possibility that this is not empty array, which seems to be the only case when you increment added value
err? reject(err): resolve(result);
});
});
}
exports = module.exports = function(req, res){ // I think it is 'exports' not 'exposts'
service(params)
.then(function(svcResult) {
var promises = svcResult.map(function(item){
rtn.count++;
return pExec(item.id).then(function(result){
if (result.length == 0) {
result = new Artifact.model({
//... populate from item ....
});
result.save(); // again this might be an async call whose response you might need before incrementing added...
rtn.added++; // <-- not seen in api response
};
});
});
Promise.all(promises).then(function(){
res.apiResponse(rtn);
});
});
}
Thanks... Here is what I have come up with so far....
function getArtifact(id) {
return new Promise(function (resolve, reject) {
Artifact.model.findOne()
.where({artifactId: id})
.exec(function (err, artifact) {
err ? resolve(null) : resolve(artifact);
});
});
}
function createArtifact(item) {
return new Promise(function (resolve, reject) {
var artifact = new Artifact.model({
// ... populate from item ....
});
artifact.save(function (err, artifact) {
err ? resolve(null) : resolve(artifact);
});
});
}
exports = module.exports = function (req, res) {
var rtn = {
success: false,
count: 0,
section: '',
globalLibrary: {
Added: 0,
Matched: 0
},
messages: [],
};
if (!req.user || !req.user._id) {
rtn.messages.push("Requires Authentication");
return res.apiResponse(rtn);
}
if (!req.params.section) {
rtn.messages.push("Invalid parameters");
return res.apiResponse(rtn);
}
var userId = req.user._id;
var section = req.params.section;
rtn.section = section;
service(section)
.then(function (svcResult) {
if (svcResult.length == 0 || svcResult.items.length == 0) {
rtn.messages.push("Retrieved empty collection");
return;
}
rtn.messages.push("Retrieved collection");
var artifacts = svcResult.items(function (item) {
rtn.count++;
return getArtifact(item.objectid)
.then(function (artifact) {
if (!artifact || artifact.length == 0) {
rtn.messages.push("Global Library Adding: " + item.name['$t']);
rtn.globalLibrary.Added++;
artifact = createArtifact(item);
} else {
rtn.globalLibrary.Matched++;
}
return artifact;
})
});
Promise.all(artifacts)
.then(function () {
rtn.success = true;
res.apiResponse(rtn);
});
});
}
Related
I am trying to store API results into an array.
The data is displayed in console, but on pushing the data into an array, the array is still empty.
Here's the code:
app.post('/fetchFavoriteTweets/', verifyToken, function(req, res) {
var favorites = [];
dbConn.then( function (database) {
var dbo = database.db("twitter_search");
dbo.collection('users').findOne(
{ _id: ObjectId(req.userId) }, function(err, result) {
if(err) throw err;
if(!result.hasOwnProperty('favorite_tweets')) {
res.status(404).json({msg:'record not found'});
}
else {
result.favorite_tweets.forEach(function (tweet) {
T.get('statuses/show', {id: tweet.id}, function(err, data, response) {
if(!err){
favorites.push(data);
console.log(data); //this returns data
} else {
console.log(err);
}
});
});
console.log(favorites);
// res.status(200).json({msg:'success', data:favorites});
}
});
}).catch(function(e){console.log(e)})
});
It looks like you're defining the favorites array within the scope of the function callback. Try putting var favorites = []; above you app.post() call instead.
Also, keep in mind that it will only have a value after the callback is complete, so any synchronous code later down the line will only see the empty array value.
I've updated your code to get favorites by storing separately the promise and call it afterwards:
UPDATE
As you can see in the demo, i have 2x console.log at the bottom, the first one(C1) is contained in the promise favoritesPromise () and the second (C2) is after the promise.
Synchronous actions will never wait for asynchronus actions to take place, therefore in my example C2 will always be outputted before C1, even if console.log(1 ... ) is before console.log(2 ... ), they'll appear reversed in the console.
In the promise i added a setTimeout of 1ms to mock a request, it was all it took to achieve the current output. Another thing you can test is removing the setTimeout then output will change a bit, your promise becomes synchronus until it reaches resolve(favorites), that means favorites has all the data by now, but when resolve takes place, it becomes async, and in your console you will still see C2 first (but now with data) and C1 second.
In my earlier answer i tried to implement this reasoning to your code.
Keep it async folks!
var favorites = [];
var favoritesPromise = () => {
return new Promise((resolve, reject) => {
console.log('Retrieving data from the internet.');
// This timeout mocks your request to anything that is async or promie
setTimeout(() => {
console.log('Request done')
let resultFavorite_tweets = [{
id: 1,
name: 'a dog'
}, {
id: 2,
name: 'a cat'
}];
resultFavorite_tweets.forEach(item => {
favorites.push(item.name);
})
resolve(favorites);
// if you have an error use
// reject(err)
}, 1);
});
}
favoritesPromise().then(favList => {
console.log(1, 'this will always contain data from the internet, but will always be last', favList);
})
console.log(2, 'this will be empty (unless you remove setTimeout), but will always be first', favorites);
app.post('/fetchFavoriteTweets/', verifyToken, function(req, res) {
const favoritesPromise = () => {
return new Promise((resolve, reject) => {
var favorites = [];
dbConn.then(function(database) {
var dbo = database.db("twitter_search");
dbo.collection('users').findOne({
_id: ObjectId(req.userId)
}, function(err, result) {
if (err) reject(err);
if (!result.hasOwnProperty('favorite_tweets')) {
res.status(404).json({
msg: 'record not found'
});
} else {
result.favorite_tweets.forEach(function(tweet) {
T.get('statuses/show', {
id: tweet.id
}, function(err, data, response) {
if (!err) {
favorites.push(data);
console.log(data); //this returns data
} else {
console.log(err);
reject(err);
}
});
resolve(data);
});
console.log(favorites);
// res.status(200).json({msg:'success', data:favorites});
}
});
}).catch(function(e) {
reject(e)
})
});
}
// Here you call the promise to retrieve "favorites"
favoritesPromise().then(favoritesList => {
console.log('your favorites array', favoritesList)
})
})
Try next code
app.post('/fetchFavoriteTweets/', verifyToken, function (req, res) {
var favorites = [];
dbConn.then(function (database) {
var dbo = database.db("twitter_search");
dbo.collection('users').findOne(
{ _id: ObjectId(req.userId) }, function (err, result) {
if (err) throw err;
if (!result.hasOwnProperty('favorite_tweets')) {
res.status(404).json({ msg: 'record not found' });
}
else {
// Counter
let count = result.favorite_tweets.length;
result.favorite_tweets.forEach(function (tweet) {
T.get('statuses/show', { id: tweet.id }, function (err, data, response) {
// Decrease count
count -= 1;
if (!err) {
favorites.push(data);
// Check if count is zero
if (count === 0) {
console.log(favorites);
res.status(200).json({msg:'success', data:favorites});
}
} else {
console.log(err);
}
});
});
}
});
}).catch(function (e) { console.log(e) })
});
I have read other related posts and still am not understanding correctly how to use promises.
router.get('/', ensureAuthenticated, function(req, res) {
let promiseToGetResponses = new Promise(function(resolve, reject) {
var indexData = new getIndexData();
resolve(indexData);
console.log('received ' + indexData.length);
});
promiseToGetResponses.then(function(data) {
console.log('then data length ' + data.length);
res.render('index', {rsvpsIn: data});
}).catch(function() { });
});
Console shows this:
received undefined
then data length undefined
returned 1 *** this is from a console.log inside the getIndexData().
The function is getting the data, but my promise usage is not waiting for it.
Thanks.
P.S. I didn't know the getIndexData function was needed. Here it is:
function getIndexData(){
RSVP.find({response: 'in'}, function (err, data) {
if (err) throw err;
// This will be a list of all responses to show in the view
var rsvpsIn = [];
if (data.length > 0) {
// Use because the foreach loop below has async calls.
var responseCounter = data.length;
data.forEach(function(response) {
var foundUser = User.getUserById(response.userId, function(err, user) {
var newRSVP = {userName: user.username, notes: response.notes};
rsvpsIn.push(newRSVP);
// decrement and if we are done, return list
responseCounter -= 1;
if (responseCounter == 0) {
console.log('returned ' + rsvpsIn.length);
return rsvpsIn;
}
});
});
} else {
return rsvpsIn;
}
});
}
Not familiar with RSVP but it appears to be callback based API, so you should wrap it in a promise and just use the promise directly:
function getIndexData(){
return new Promise((resolve, reject) => {
RSVP.find({response: 'in'}, function (err, data) {
if (err) reject(err);
// This will be a list of all responses to show in the view
var rsvpsIn = [];
if (data.length > 0) {
// Use because the foreach loop below has async calls.
var responseCounter = data.length;
data.forEach(function(response) {
var foundUser = User.getUserById(response.userId, function(err, user) {
var newRSVP = {userName: user.username, notes: response.notes};
rsvpsIn.push(newRSVP);
// decrement and if we are done, return list
responseCounter -= 1;
if (responseCounter == 0) {
console.log('returned ' + rsvpsIn.length);
resolve(rsvpsIn);
}
});
});
} else {
resolve(rsvpsIn);
}
});
});
}
then just use it where you use the promise:
router.get('/', ensureAuthenticated, function(req, res) {
getIndexData().then(function(data) {
console.log('then data length ' + data.length);
res.render('index', {rsvpsIn: data});
}).catch(function() { });
});
I have a piece of code which deals with user's data. There are bunch of nested function calls :
f1(){
f2(){
....
fn{
///
}
}
}
fn accesses a database which means it's asynchronous, so I wrote it somehow that it returns a promise and in fn-1 (the function which calls fn) , we use .then() to wait for this promise. But it looks like now I have to return a promise in fn-1 and so on. Is that true ?
var keyValueExists = function(key, value) {
var query = {};
query[key] = value;
return new Promise(function(resolve, reject) {
User.count(query, function(err, count) {
if (err) {
console.log(err);
console.log('Problem with `.find` function');
reject('Problem with `.find` function');
} else {
resolve(count !== 0);
}
});
});
};
var addUser = function(newUserInfo) {
var validationResult = Common._validateUserInfo(newUserInfo);
if (validationResult.isOK) {
keyValueExists('userName', newUserInfo.userName).then(function(userNameAlreadyExists) {
if (userNameAlreadyExists) {
validationResult = {
isOK: false,
reason: 'Username already exists',
infoWithBadInput: 'userName'
}
} else {
var newUserId = generateUserId();
//TODO: change it somehting more flexible. e.g. a predefined list of attributes to iterate over
var newUser = {
'userName': newUserInfo.userName,
'password': newUserInfo.password,
'userId': newUserId,
'lastModificationTime': Common.getCurrentFormanttedTime(),
'createdTime': Common.getCurrentFormanttedTime()
};
var user = new User(newUser);
user.save(function(err) {
if (err) {
console.log(err);
console.log('There is a problem saving the user info');
} else {
console.log('A new user added: ');
console.log(newUser);
}
});
}
return validationResult;
});
} else {
return validationResult;
}
};
addUser returns undefined ! It looks like that the caller of addUser doesn't wait for it !
This is what you are effectively doing in your addUser function
var addUser = function(newUserInfo) {
var validationResult = Common._validateUserInfo(newUserInfo);
if (validationResult.isOK) {
// ... do something asynchronously without returning anything
} else {
return validationResult;
}
}
So, yeah, if validationResult.isOK, adduser WILL return undefined
Here's some code loosely based on your code, but it runs standalone to demonstrate how you possibly should be doing things
var keyValueExists = function(key, value) {
// pseudo junk, this simulates any username starting with b as existing
return new Promise(function(resolve, reject) {
resolve(value.substr(0,1) == 'b'); // barny and betty are dupes, fred and wilma are not
});
}
var addUser = function (newUserInfo) {
// var validationResult = Common._validateUserInfo(newUserInfo);
var validationResult = {isOK: !!~(['fred', 'barny'].indexOf(newUserInfo.userName)), username: newUserInfo.userName}; // dummy code
if (validationResult.isOK) {
return keyValueExists('userName', newUserInfo.userName).then(function (userNameAlreadyExists) {
if (userNameAlreadyExists) {
validationResult = {
isOK: false,
reason: 'Username already exists',
infoWithBadInput: 'userName',
username: newUserInfo.userName
}
} else {
// create new user here
validationResult.userNumber = (Math.random() * 100000000) | 0;
}
return validationResult;
});
}
else {
// this function always needs to return a promise, even if it is resolved/rejected immediately
return Promise.reject(validationResult);
}
}
addUser({userName: 'fred'}).then(function (result) {
console.log(result);
}).catch(function(err) {
console.error(err);
});
addUser({userName: 'wilma'}).then(function (result) {
console.log(result);
}).catch(function(err) {
console.error(err);
});
addUser({userName: 'barny'}).then(function (result) {
console.log(result);
}).catch(function(err) {
console.error(err);
});
addUser({userName: 'betty'}).then(function (result) {
console.log(result);
}).catch(function(err) {
console.error(err);
});
I want to convert the following code to use promise. It is working and output a user's attributes within the active directory.
var client = ldap.createClient({
url: ldap_url
});
client.bind(ldap_username, ldap_password, function (err) {
client.search(ldap_dn_search, opts, function (err, search) {
search.on('searchEntry', function (entry) {
var user = entry.object;
// It is working!!!. It outputs all user attributes.
console.log(user);
});
});
});
The following is my attempt, butit doesn't output anything.
var Promise = require('promise');
var client_bind = Promise.denodeify(client.bind);
var client_search = Promise.denodeify(client.search);
client_bind(ldap_username, ldap_password)
.then(function(err){
client_search(ldap_dn_search, opts)
.then(function(search){
var search_on = Promise.denodeify(search.on);
search_on('searchEntry')
.then(function(entry){
var user = entry.object;
// It doesn't output anything !!!
console.log(user);
});
});
});
I had the same problem.
Search emits events, so we need something that processes them and passes further along the chain.
Here is piece of code, that works for me:
var ldap = require('ldapjs');
var promise = require('bluebird');
var client = ldap.createClient({url: app.settings['ldap']['server']});
var uid;
promise.promisifyAll(client);
function searchPromise(res, notfoundtext) {
return new Promise(function(resolve, reject) {
var found = false;
res.on('searchEntry', function(entry) {
found = true;
resolve(entry);
});
res.on('error', function(e) {
reject(e.message);
});
res.on('end', function() {
if (!found) {
reject(notfoundtext);
}
});
});
}
client.searchAsync(app.settings['ldap']['baseDn'], {filter: '(mail='+credentials.email+')', scope: 'sub'})
.then(function(res) {
return searchPromise(res, 'User isn\'t exists.');
})
.then(function (entry) {
uid = entry.object.uid;
return client.bindAsync(entry.object.dn, credentials.password);
})
.then(function() {
return client.searchAsync('cn='+app.settings['ldap']['group']+',cn=groups,'+app.settings['ldap']['baseDn'], {scope: 'sub', filter: '(memberUid='+uid+')'});
})
.then(function(res) {
return searchPromise(res, 'User is not in group ' + app.settings['ldap']['group']);
})
.then(function() {
console.log('All is ok');
})
.catch(function(message) {
console.log('Error:' + message);
});
Immediately after the search I add one more step that catches the events, processes them, and passes it further along the chain. This makes the function searchPromise.
Good luck coding )
Most likely those methods do require to be called on client as a context, so you will need to bind() them before passing them to Promise.denodeify:
var client_bind = Promise.denodeify(client.bind.bind(client));
var client_search = Promise.denodeify(client.search.bind(client));
Also, a proper use of promises would look like this:
client_bind(ldap_username, ldap_password).then(function() {
return client_search(ldap_dn_search, opts);
// ^^^^^^ always return something from the callback
}).then(function(search) { // flatten your chain
return Promise.denodeify(search.on).call(search, 'searchEntry');
// ^^^^^^ an alternative to `bind`
}).then(function(entry){
var user = entry.object;
console.log(user);
}).catch(function(err) { // always catch errors!
console.error(err);
});
Using Bluebird Promises, the easy way to do this is to create your client normally, and then run the promisifyAll() on the client.
var ldap = require('ldapjs');
var Promise = require('bluebird');
var client = ldap.createClient({
url: 'ldap://my-server:1234',
});
Promise.promisifyAll(client);
Now you can call client.addAsync() and client.searchAsync() and such.
client.bindAsync(secUserDn, secUserPassword)
.then(doSearch) // if it works, call doSearch
.catch(function (err) { // if bind fails, handle it
console.error('Error on bind', err)
});
function doSearch(data) {
client.searchAsync('CN=A Test,OU=Users,DC=website,DC=com', options)
.then(function (data) { // Handle the search result processing
console.log('I got a result');
})
.catch(function (err) { // Catch potential errors and handle them
console.error('Error on search', err);
});
}
i had the same issue here but i solved it by adding promise and resolve the response without using bluebird, this is an exemple of my code :
async getLdapUser(username: any): Promise<any> {
let myPromise = new Promise<boolean>((resolve, reject) => {
console.log('ssssssssss', username);
const adSuffix = 'OU=xxxx,OU=xxxxx,DC=xxxxxxx,DC=xxxxxx';
const password = 'xxxxxxxxxxxxx';
// Create client and bind to AD
const client = ldap.createClient({
url: 'ldap://1.1.1.1:389',
});
// promise.promisifyAll(client);
let resp = false;
// console.log(client);
client.bind('userTest', password,(err: any) => {
console.log('RESP', resp);
if (err) {
console.log('Error in new connetion ' + err);
} else {
/*if connection is success then go for any operation*/
console.log('Success');
const searchOptions: {} = {
scope: 'sub',
filter: '(sAMAccountName=' + username + ')',
attributes: ['sAMAccountName'],
};
client.search(adSuffix, searchOptions, (err: any, res: any) => {
assert.ifError(err);
res.on('searchEntry', (entry: any) => {
resp = true;
});
res.on('error', (error: any) => {
console.log('err');
reject(error.message);
});
await res.on('end', (result: any) => {
resolve(resp);
});
});
}
});
});
return myPromise;
}
(First: I'm sorry, I don't speak english very well!)
I wanna return the results of 3 finds in one array.
My code (next) is running well, but I'm in callback hell!
_Schema
.static('retrieveAll', function(cb) {
query = {};
this.find(query, function(err, data) {
if(err) {
cb(err, null);
return;
}
if(data)
all = data;
else
all = [];
_StoresModel.find(query).select('contact address').exec(function(err, data) {
if(err) {
cb(err, null);
return;
}
if(data) {
all = data.reduce(function(coll, item) {
coll.push(item);
return coll;
}, all);
}
_CustomersModel.find(query).select('contact address').exec(function(err, data) {
if(err) {
cb(err, null);
return;
}
if(data) {
all = data.reduce(function(coll, item) {
coll.push(item);
return coll;
}, all);
}
cb(null, all);
});
});
});
});
I've a FIND inside a FIND inside a FIND.
Is there anyway to improve this?
SOLUTION:
_Schema
.static('retrieveAll', function(cb) {
var model = this;
_async.parallel(
{ contacts: function(cb) {
model.find({}).exec(cb);
}
, stores: function(cb) {
_StoresModel.find({}).select('contact address').exec(cb);
}
, costumers: function(cb) {
_CostumersModel.find({}).select('contact address').exec(cb);
}
}
, function(err, data) {
if(err) {
cb(err, null);
return
}
var ret = [];
if(data.contacts.length > 0) {
ret = ret.concat(data.contacts);
}
if(data.stores.length > 0) {
ret = ret.concat(data.stores);
}
if(data.costumers.length > 0) {
ret = ret.concat(data.costumers);
}
cb(null, ret);
});
You can try using Promises.
(untested) example:
var RSVP = require('rsvp');
var all = [];
_Schema.static('retrieveAll', function(cb) {
query = {};
findPromise(this, query)
.then(function (data) {
all = data;
return findPromise(_StoresModel, query, 'contact address');
})
.then(function (stores) {
all = all.concat(stores);
return findPromise(_CustomersModel, query, 'contact address');
})
.then(function (customers) {
all = all.concat(customers);
cb(null, all);
})
.catch(function (err) {
cb(err, null);
});
});
function findPromise(Model, query, select) {
return new RSVP.Promise(function (resolve, reject) {
Model.find(query).select(select || '*').exec(function (err, data) {
return err ? reject(err) : resolve(data);
});
});
}
That example is using RSVP, but there are also other promise implementations such as Q and bluebird.
And a side note, you can use concat to concatenate arrays instead of using reduce.
take a look at npm Async. It a great library of different patterns that can be used on node.js.
You will probably want to use the waterfall if there is a Chronological priority or parallel pattern if they can all execute in parallel.
Some server-side promise libraries like q and bluebird would clean up your code substantially and eliminate the mess of callback hell.