below is my couchbase nodejs code
kdatabase.js
var couchbase = require('couchbase');
var db = new couchbase.Connection({
host: "http://127.0.0.1:8091",
bucket: "default",
},
function(err) {
if (err) throw err;
db.get('id1', function(err, result) {
if (err) throw err;
console.log(result.value);
process.exit(0);
});
});
it works
but I hope to wrap it to object that can be easily to operate
module.exports = function(app) {
return new KDatabase(app);
};
var KDatabase = function(app) {
this.app = app;
};
//couchbase
KDatabase.prototype.query = function(userName) {
var couchbase = require('couchbase');
var db = new couchbase.Connection({
host: "http://127.0.0.1:8091",
bucket: "default",
},
function(err) {
if (err) throw err;
console.log(userName + '!!!!--');
db.get(userName, function(err, result) {
if (err) throw err;
var o = result.value;
console.log(o['password'] + '***--');
return o['password'];
});
});
};
then I call
var db = require('kdatabase.js')();
var s = db.query(msg.username, function(err) {
if (err) {
console.log('aaa');
}
console.log('bbb');
return;
});
the lines
console.log(userName + '!!!!--');
console.log(o['password'] + '***--');
display correctly
but
console.log('aaa');
console.log('bbb');
are never executed
Your query method does not take a callback argument, so you never call it.
KDatabase.prototype.query = function(userName, cb) {
/* snip */
console.log(o['password'] + '***--');
cb(err, result);
Related
I am new to async library. I have used async.eachSeries and async.waterfall for each iteration. I see, the async.waterfall runs only once.
Here is my code :
var fs = require('fs'),
async = require('async'),
Client = require('node-rest-client').Client;
// REST API Call and output in jsonOutput.results
console.log(jsonOutput.results.length); // jsonOutput.results has 124 records.
async.eachSeries(jsonOutput.results, function(account, callback) {
var dataObject = {};
dataObject.updatetime = new Date();
var setAccountInfoURL = ""; // Data Update REST API Request
async.waterfall([
function setAccountInfo(updateCallback) {
// client.get(setAccountInfoURL, function (data, response) {
// var jsonOutput = JSON.parse(data.toString('utf8'));
updateCallback(null, "output", account)
// });
},
function saveAccountInfo(jsonOutput, account, updateCallback) {
var debuglog = JSON.stringify(account) + "\n" + jsonOutput;
fs.appendFile("debuginfo.json", debuglog + "\n", function (err) {
if(err) {
console.log(err);
}
console.log("JSON saved to " + "debuginfo.json");
updateCallback(null);
});
}
],function asyncComplete(err) {
if (err) {
console.warn('Error setting account info.', err);
}
console.log('async completed');
});
}, function(err){
if (err) {
console.log('error in loop');
}
console.log('loop completed');
});
Output:
124
JSON saved to debuginfo.json
async completed
Any help is really appreciated.
I found my mistake. I missed calling the callback after each iteration just after async is completed.
var fs = require('fs'),
async = require('async'),
Client = require('node-rest-client').Client;
// REST API Call and output in jsonOutput.results
console.log(jsonOutput.results.length); // jsonOutput.results has 124 records.
async.eachSeries(jsonOutput.results, function(account, callback) {
var dataObject = {};
dataObject.updatetime = new Date();
var setAccountInfoURL = ""; // Data Update REST API Request
async.waterfall([
function setAccountInfo(updateCallback) {
// client.get(setAccountInfoURL, function (data, response) {
// var jsonOutput = JSON.parse(data.toString('utf8'));
updateCallback(null, "output", account)
// });
},
function saveAccountInfo(jsonOutput, account, updateCallback) {
var debuglog = JSON.stringify(account) + "\n" + jsonOutput;
fs.appendFile("debuginfo.json", debuglog + "\n", function (err) {
if(err) {
console.log(err);
}
console.log("JSON saved to " + "debuginfo.json");
updateCallback(null);
});
}
],function asyncComplete(err) {
if (err) {
console.warn('Error setting account info.', err);
}
console.log('async completed');
callback(null); // this is the change.
});
}, function(err){
if (err) {
console.log('error in loop');
}
console.log('loop completed');
});
Users upload files into my express app. I need to calc hash of the uploaded file and then write file to disk using calculated hash as a filename. I try to do it using the following code:
function storeFileStream(file, next) {
createFileHash(file, function(err, hash) {
if (err) {
return next(err);
}
var fileName = path.join(config.storagePath, hash),
stream = fs.createWriteStream(fileName);
stream.on('error', function(err) {
return next(err);
});
stream.on('finish', function() {
return next();
});
file.pipe(stream);
});
}
function createFileHash(file, next) {
var hash = crypto.createHash('sha1');
hash.setEncoding('hex');
file.on('error', function(err) {
return next(err);
});
file.on('end', function(data) {
hash.end();
return next(null, hash.read());
});
file.pipe(hash);
}
The problem is that after I calc file hash the writed file size is 0. What is the best way do solve this task?
Update
According #poke suggestion I try to duplicate my stream. Now my code is:
function storeFileStream(file, next) {
var s1 = new pass;
var s2 = new pass;
file.pipe(s1);
file.pipe(s2);
createFileHash(s1, function(err, hash) {
if (err) {
return next(err);
}
var fileName = path.join(config.storagePath, hash),
stream = fs.createWriteStream(fileName);
stream.on('error', function(err) {
return next(err);
});
stream.on('finish', function() {
return next();
});
s2.pipe(stream);
});
}
function createFileHash(file, next) {
var hash = crypto.createHash('sha1');
hash.setEncoding('hex');
file.on('error', function(err) {
return next(err);
});
file.on('end', function(data) {
hash.end();
return next(null, hash.read());
});
file.pipe(hash);
}
The problem of this code is that events end and finish are not emited. If I comment file.pipe(s2); events are emited, but I again get my origin problem.
This code fix the problem:
var s1 = new passThrough,
s2 = new passThrough;
file.on('data', function(data) {
s1.write(data);
s2.write(data);
});
file.on('end', function() {
s1.end();
s2.end();
});
The correct and simple way should be as follow:
we should resume the passthroughed stream
function storeFileStream(file, directory, version, reject, resolve) {
const fileHashSource = new PassThrough();
const writeSource = new PassThrough();
file.pipe(fileHashSource);
file.pipe(writeSource);
// this is the key point, see https://nodejs.org/api/stream.html#stream_three_states
fileHashSource.resume();
writeSource.resume();
createFileHash(fileHashSource, function(err, hash) {
if (err) {
return reject(err);
}
const fileName = path.join(directory, version + '_' + hash.slice(0, 8) + '.zip');
const writeStream = fs.createWriteStream(fileName);
writeStream.on('error', function(err) {
return reject(err);
});
writeStream.on('finish', function() {
return resolve();
});
writeSource.pipe(writeStream);
});
}
function createFileHash(readStream, next) {
const hash = crypto.createHash('sha1');
hash.setEncoding('hex');
hash.on('error', function(err) {
return next(err);
});
hash.on('finish', function(data) {
return next(null, hash.read());
});
readStream.pipe(hash);
}
You could use the async module (not tested but should work):
async.waterfall([
function(done) {
var hash = crypto.createHash('sha1');
hash.setEncoding('hex');
file.on('error', function(err) {
done(err);
});
file.on('end', function(data) {
done(null, hash.read);
});
file.pipe(hash);
},
function(hash, done) {
var fileName = path.join(config.storagePath, hash),
stream = fs.createWriteStream(fileName);
stream.on('error', function(err) {
done(err);
});
stream.on('finish', function() {
done(null);
});
file.pipe(stream);
}
], function (err) {
console.log("Everything is done!");
});
I'm trying MongoDB document insertion from a CSV stream using async.queue.
But I face this following error. I've tried all the remedies given in similar SO posts.
Exact error message is:
C:\Users\admin\node_modules\mongodb\lib\mongo_client.js:406
throw err
TypeError:object is not a function
at C:\Users\admin\Desktop\mynodefile.js:13:2
at C:\Users\admin\node_modules\mongodb\lib\mongo_client.js:403:11
at process._tickCallback(node.js:355:11)
node.js code I used:
var csv = require('csv');
var async = require('async');
var fs = require('fs');
var MongoClient = require('mongodb').MongoClient;
MongoClient.connect('mongodb://localhost:27017', function(err, db) {
if (err) throw err;
var collection = db.collection('myCSVs');
var queue = async.queue(collection.insert.bind(collection), 5);
csv()
.from.path('./input.csv', { columns: true })
.transform(function (data, index, cb) {
queue.push(data, function (err, res) {
if (err) return cb(err);
cb(null, res[0]);
});
})
.on('error', function (err) {
console.log('ERROR: ' + err.message);
})
.on('end', function () {
queue.drain = function() {
collection.count(function(err, count) {
console.log('Number of documents:', count);
db.close();
});
};
});
});
You haven't mentioned the database name in your MongoClient.connect function call. You can do so like this:
MongoClient.connect('mongodb://localhost:27017/database_name',function(err, db) {
Then you can do:
var collection = db.collection('myCSVs');
If myCSVs is a collection inside database_name
Or you can also do:
MongoClient.connect('mongodb://localhost:27017',function(err, mongoclient) {
var db = mongoclient.db('database_name');
var collection = db.collection('myCSVs');
});
You have to change
var queue = async.queue(collection.insert.bind(collection), 5);
Into:
var q = async.queue(function (task, callback) {
console.log('hello ' + task.name);
callback();
}, 2);
IN this line :
queue.push(data, function (err, res) {
if (err) return cb(err);
cb(null, res[0]);
});
you are calling push with data and with a callback, but its not implemented in your
var queue = async.queue(collection.insert.bind(collection), 5);
Is there a way to block the asynchronous callback property of node.js?
Please Advice...
For example,
var express = require('express');
var app = express();
var MongoClient = require('mongodb').MongoClient,
format = require('util').format;
var cors = require('cors');
app.get('/gantt', cors(), function (request, response) {
MongoClient.connect('mongodb://127.0.0.1:27017/test', function (err, db) {
if (err) throw err;
var collection = db.collection('ganttdata');
collection.find({}, {
"_id": 0
}).toArray(function (err, results) {
var jsonString = JSON.stringify(results);
response.setHeader('Content-Type', 'text/plain');
response.send('{\"data\":' + jsonString + '}');
});
});
});
app.listen(3000);
console.log('Listening on port 3000...');
Inspite the Node.js prints the console statement first,i want app.get() to be executed.
My scenario is same as that of the above one.
This is my scenario
var ganttresult = new Array();
app.get('/get', cors(), function (request, response) {
console.log('hello');
connection.query("SELECT distinct id FROM ganttdata", function (err, rows) {
if (err) {
console.log('error in fetching ' + err);
} else {
var all_id = rows;
for (var j = 0; j < all_id.length; j++) {
console.log('hello1');
connection.query("SELECT id,tailName FROM ganttdata where id= '" + all_id[j].id + "'", function (err, rows) {
if (err) {
console.log('error in fetching ' + err);
} else {
var jsonString1 = rows;
var set_id = jsonString1[0].id;
connection.query("SELECT item_id,name,start,end FROM ganttdata where id= '" + set_id + "'", function (err, rows) {
if (err) {
console.log('error in fetching ' + err);
} else {
var jsonString2 = rows;
var gantt1 = new Object();
gantt1.id = jsonString1[0].id;
gantt1.tailName = jsonString1[0].tailName;
var series = new Array();
for (var i = 0; i < jsonString2.length; i++) {
var gantt2 = new Object();
gantt2.item = jsonString2[i];
series.push(gantt2);
gantt1.series = series;
}
//console.log(gantt1);
console.log('hi');
ganttresult.push(gantt1);
console.log(ganttresult);
}
});
}
});
}
var result = JSON.stringify(ganttresult);
console.log(result);
response.send('{\"data\":' + result + '}');
response.end();
}
});
});
When I run this code,
I get an empty resultset and when I re-run I get the result.
I guess it is due to asynchronous callback nature of node js.
Please advice...
Thanks
I have tried async.waterfall method as given below
app.get('/get',cors(), function(request,response) {
async.waterfall([
function(result) {
connection.query("SELECT id FROM Gantt",function(err, rows) {
if (err) {
console.log('error in fetching ' + err);
}
else{
var all_id=rows;
for(var j=0;j<all_id.length;j++){
connection.query("SELECT id,tailName FROM Gantt where id= '"+all_id[j].id+"'",function(err, rows) {
if (err) {
console.log('error in fetching ' + err);
}
else{
var jsonString1=rows;
var set_id=jsonString1[0].id;
connection.query("SELECT item_id,name,start,end FROM GanttFlight where id= '"+set_id+"'",function(err, rows) {
if (err) {
console.log('error in fetching ' + err);
}
else{
var jsonString2=rows;
var gantt1=new Object();
gantt1.id=jsonString1[0].id;
gantt1.name=jsonString1[0].tailName;
var series = new Array();
series=[];
for(var i=0;i<jsonString2.length;i++){
var gantt2=new Object();
gantt2.item=jsonString2[i];
series.push(gantt2);
gantt1.series=series;
}
ganttresult.push(gantt1);
}
});
}
});
}
var result= JSON.stringify(ganttresult);
console.log(ganttresult);
response.send(ganttresult);
ganttresult=[];
//response.send('{\"data\":'+result+'}');
response.end();
}
});
}
], function(err, status) {
console.log(status);
});
});
app.listen(3000);
console.log('Listening on port 3000...');
i am getting empty result first and when refresh the browser,i get the required result
Please Advice
I am having trouble understanding node.js.
Example, MongoDB access, here's what I've got (mydb.js):
var mongodb = require('mongodb'),
server = new mongodb.Server('staff.mongohq.com', 10030, {
auto_reconnect: true
}),
db = new mongodb.Db('mydb', server);
function authenticateAndGo(db, handle) {
db.authenticate('username', 'password', function(err) {
if (err) {
console.log(err);
return;
}
console.log('Database user authenticated');
var collection = new mongodb.Collection(db, 'test');
handle(collection);
});
}
function query(handle) {
db.open(function(err, db) {
if( err ) {
console.log(err);
return;
}
console.log('Database connected');
authenticateAndGo(db, handle);
});
};
exports.query = query;
So, if I want to use it later, I would
var mydb = require('./mydb');
mydb.query(function(collection) {
collection.find({}, {
limit: 10
}).toArray(function(err, docs) {
console.log(docs);
});
});
But, If I do multiple calls, like so:
var mydb = require('./mydb');
mydb.query(function(collection) {
collection.find({}, {
limit: 10
}).toArray(function(err, docs) {
console.log(docs);
});
});
mydb.query(function(collection) {
collection.find({}, {
limit: 10
}).toArray(function(err, docs) {
console.log(docs);
});
});
I get an exception:
Error: db object already connecting, open cannot be called multiple times
I think that there is really something fundamental that I do not understand about all this and it is probable that this question is stupid ...
Anyway, all help is welcome.
Thanks in advance.
mydb.js:
var mongodb= require('mongodb'),
server = new mongodb.Server('staff.mongohq.com', 10030, {
auto_reconnect: true
}),
db1 = new mongodb.Db('mydb', server);
// callback: (err, db)
function openDatabase(callback) {
db1.open(function(err, db) {
if (err)
return callback(err);
console.log('Database connected');
return callback(null, db);
});
}
// callback: (err, collection)
function authenticate(db, username, password, callback) {
db.authenticate(username, password, function(err, result) {
if (err) {
return callback (err);
}
if (result) {
var collection = new mongodb.Collection(db, 'test');
// always, ALWAYS return the error object as the first argument of a callback
return callback(null, collection);
} else {
return callback (new Error('authentication failed'));
}
});
}
exports.openDatabase = openDatabase;
exports.authenticate = authenticate;
use.js:
var mydb = require('./mydb');
// open the database once
mydb.openDatabase(function(err, db) {
if (err) {
console.log('ERROR CONNECTING TO DATABASE');
console.log(err);
process.exit(1);
}
// authenticate once after you opened the database. What's the point of
// authenticating on-demand (for each query)?
mydb.authenticate(db, 'usernsame', 'password', function(err, collection) {
if (err) {
console.log('ERROR AUTHENTICATING');
console.log(err);
process.exit(1);
}
// use the returned collection as many times as you like INSIDE THE CALLBACK
collection.find({}, {limit: 10})
.toArray(function(err, docs) {
console.log('\n------ 1 ------');
console.log(docs);
});
collection.find({}, {limit: 10})
.toArray(function(err, docs) {
console.log('\n------ 2 ------');
console.log(docs);
});
});
});
Result:
on success:
Database connected
Database user authenticated
------ 1 ------
[ { _id: 4f86889079a120bf04e48550, asd: 'asd' } ]
------ 2 ------
[ { _id: 4f86889079a120bf04e48550, asd: 'asd' } ]
on failure:
Database connected
{ [MongoError: auth fails] name: 'MongoError', errmsg: 'auth fails', ok: 0 }
[Original Answer]:
You're opening the db multiple times (once in each query). You should open the database just once, and use the db object in the callback for later use.
You're using the same variable name multiple times, and that might've caused some confusion.
var mongodb = require('mongodb'),
server = new mongodb.Server('staff.mongohq.com', 10030, {
auto_reconnect: true
}),
db1 = new mongodb.Db('mydb', server);
function authenticateAndGo(db, handle) {
db.authenticate('username', 'password', function(err) {
if (err) {
console.log(err);
return;
}
console.log('Database user authenticated');
var collection = new mongodb.Collection(db, 'test');
handle(collection);
});
}
function query(handle) {
db1.open(function(err, db2) {
if( err ) {
console.log(err);
return;
}
console.log('Database connected');
authenticateAndGo(db2, handle);
});
};
exports.query = query;
I've changed the above code a little (db1 for the original db, db2 for the opened db). As you can see, you're opening db1 multiple times, which is not good. extract the code for opening into another method and use it ONCE and use the db2 instance for all your queries/updates/removes/...
You can only call "open" once. When the open callback fires, you can then do your queries on the DB object it returns. So one way to handle this is to queue up the requests until the open completes.
e.g MyMongo.js
var mongodb = require('mongodb');
function MyMongo(host, port, dbname) {
this.host = host;
this.port = port;
this.dbname = dbname;
this.server = new mongodb.Server(
'localhost',
9000,
{auto_reconnect: true});
this.db_connector = new mongodb.Db(this.dbname, this.server);
var self = this;
this.db = undefined;
this.queue = [];
this.db_connector.open(function(err, db) {
if( err ) {
console.log(err);
return;
}
self.db = db;
for (var i = 0; i < self.queue.length; i++) {
var collection = new mongodb.Collection(
self.db, self.queue[i].cn);
self.queue[i].cb(collection);
}
self.queue = [];
});
}
exports.MyMongo = MyMongo;
MyMongo.prototype.query = function(collectionName, callback) {
if (this.db != undefined) {
var collection = new mongodb.Collection(this.db, collectionName);
callback(collection);
return;
}
this.queue.push({ "cn" : collectionName, "cb" : callback});
}
and then a sample use:
var MyMongo = require('./MyMongo.js').MyMongo;
var db = new MyMongo('localhost', 9000, 'db1');
var COL = 'col';
db.query(COL, function(collection) {
collection.find({}, {
limit: 10
}).toArray(function(err, docs) {
console.log("First:\n", docs);
});
});
db.query(COL, function(collection) {
collection.find({}, {
limit: 10
}).toArray(function(err, docs) {
console.log("\nSecond:\n", docs);
});
});
I simply call the open function once directly after the db init:
var mongodb = require('mongodb');
var server = new mongodb.Server('foo', 3000, {auto_reconnect: true});
var db = new mongodb.Db('mydb', server);
db.open(function(){});
After that I do not have to care about that anymore because of auto_reconnect is true.
db.collection('bar', function(err, collection) { [...] };