function load_file_contents(path, callback) {
fs.open(path, 'r', function (err, f) {
if (err) {
callback(err);
return;
} else if (!f) {
callback(make_error("invalid_handle",
"bad file handle from fs.open"));
return;
}
fs.fstat(f, function (err, stats) {
if (err) {
callback(err);
return;
}
if (stats.isFile()) {
var b = new Buffer(10000);
fs.read(f, b, 0, 10000, null, function (err, br, buf) {
if (err) {
callback(err);
return;
}
fs.close(f, function (err) {
if (err) {
callback(err);
return;
}
callback(null, b.toString('utf8', 0, br));
});
});
} else {
calback(make_error("not_file", "Can't load directory"));
return;
}
});
});
}
load_file_contents(
"test.txt",
function (err, contents) {
if (err)
console.log(err);
else
console.log(contents);
}
);
In this code, I don't quite understand where does this "f" come from?
after "fs.open()", there is a line
" } else if (!f) {"
what does this mean, where does this f comefrom?
f is the file descriptor that is passed to fs.open()'s callback if the file was able to be opened.
else if (!f) {
callback(make_error("invalid_handle",
"bad file handle from fs.open"));
return;
}
is checking if the file descriptor is falsy (presumably it's checking if it's null or undefined) and calling the function's own callback with an error.
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);
}
});
},
I keep getting this error (after a certain amount of time) when i refresh the my 'members area' after login. I use response.redirect to redirect to the area (success) or back to sign in form (error). How can i fix this?
app.get('/sellers/login', function(request, response) {
if(request.session.sellerId){
response.redirect( '/sellers/area?logged_in=true');
}
else{
response.render('pages/sellers-login');
}
});
app.post('/authenticate', function(request, response) {
if(request.session.sellerId){
response.redirect('/area?logged_in=true');
}
else{
db.authenticate(request.body.loginid, function(err, results) {
if(err){
response.redirect('/sellers/login?err=1&logged_in=false&type=db');
}
else{
if(results.length >=1){
var hash = results[0]['hash'];
var seller_id = results[0]['id'];
bcrypt.compare(request.body.password, hash, function(err, res) {
if(res){
request.session.sellerId = seller_id;
response.redirect('/sellers/area?logged_in=true');
}
else{
response.redirect('/sellers/login?err=1&logged_in=false&type=pMatch');
}
});
}
else{
response.redirect('/sellers/login?err=1&logged_in=false&type=user');
}
}
});
}
});
app.get('/sellers/area', function(request, response) {
if(request.session.sellerId){
response.render('pages/sellers-area');
}
else{
response.redirect('/sellers/login?not_logged_in=true');
}
});
if(request.session.sellerId){
response.redirect('/area?logged_in=true');
}
db.authenticate(request.body.loginid, function(err, results) {
// ....
});
You send the header when request.session.sellerId evaluates to true by calling the response.redirect, but you continue with the the db.authenticate afterwards.
Inside of that callback you will do another redirect, even when your redirect for that response has already taken place.
Inside of the db.authenticate you have the same problem with the if(err)
EDIT
you need to use an else block (or a return) for both the if (request.session.sellerId) and the if (err) {
if (request.session.sellerId) {
response.redirect('/area?logged_in=true');
} else {
db.authenticate(request.body.loginid, function(err, results) {
if (err) {
response.redirect('/sellers/login?err=1&logged_in=false&type=db');
} else if (results.length >= 1) {
var hash = results[0]['hash'];
var seller_id = results[0]['id'];
bcrypt.compare(request.body.password, hash, function(err, res) {
if (res) {
request.session.sellerId = seller_id;
response.redirect('/sellers/area?logged_in=true');
} else {
response.redirect('/sellers/login?err=1&logged_in=false&type=pMatch');
}
});
} else {
response.redirect('/sellers/login?err=1&logged_in=false&type=user');
}
});
}
I think i've found precisely where the error originates from which lies in the db.authenticate
//db.js
exports.authenticate = function(loginid, callback) {
var sql = "select ...";
pool.getConnection(function(err, connection) {
if(err) {
console.log(err);
callback(true);
return;
}
connection.query(sql, [loginid], function(err, results) {
connection.release();
if(err) {
console.log(err);
callback(true);
return;
}
callback(false, results);
});
connection.on('error', function(err) {
console.log(err);
connection.release();
callback(true);
return;
});
});
};
The connection.on('error',... gets called, so the callback(true) activates causing this error.
I am a node.js noob and am trying to do some file processing. I'm using async to process an array of files but the callback function is never called. I believe this is due to calling the next() function twice but I can't see where I'm doing this. If I comment out the last "return next()" I finish with no errors but the final callback doesn't execute. If I uncomment out this line I get the error message "callback was already called". Any help would be greatly appreciated. Here is the code:
/*jslint node: true */
"use strict";
var fs = require('fs'),
dive = require('dive'),
subdirs = require('subdirs'),
async = require('async'),
currentYear = new Date().getFullYear(),
cpFile = __dirname + "/" + "header.txt",
noCopy = __dirname + "/" + "noCopyright.txt",
currentHeads = __dirname + "/" + "currentHeaders.txt",
reYear = /\s(\d{4})[-\s]/i, // matches first 4 digit year
reComment = /(\/\*(?:(?!\*\/).|[\n\r])*\*\/)/, // matches first multi-line comment
allHeaders = {},
stringObj,
year,
top;
function needsHeader (file) {
if ((file.match(/.*\.js$/) || file.match(/.*\.less$/) || file.match(/.*\.groovy$/) || file.match(/.*\.java$/) || file.match(/.*\.template$/) || file.match(/.*\.html$/))) {
fs.appendFile(noCopy, file + "\n", function (err) {
if (err) {
return console.log(err);
}
});
}
}
fs.readFile(cpFile, 'utf8', function (err, copyRight) {
if (err) {
return console.log(err);
}
subdirs(__dirname, 4, function (err, dirs) {
if (err) {
return console.log(err);
}
async.each(dirs, function (dir, next) {
if (! dir.match(/.*\/src$/)) {
return next();
} else {
dive(dir, {all: false}, function (err, file) {
if (err) {
return next(err);
} else {
fs.readFile(file, 'utf8', function (err, data) {
if (err) {
return next(err);
} else {
if (data.match(reComment) && (file.match(/.*\.js$/) || file.match(/.*\.less$/) || file.match(/.*\.groovy$/) || file.match(/.*\.java$/) || file.match(/.*\.template$/))) {
top = data.match(reComment)[0];
if (top.match(reYear)) {
year = top.match(reYear)[1];
if (allHeaders[year]) {
allHeaders[year].push(file);
} else {
allHeaders[year] = [file];
}
} else {
needsHeader(file);
}
} else {
needsHeader(file);
}
return next();
}
});
}
});
}
}, function (err) {
if (err) {
console.log(err);
}
stringObj = JSON.stringify(allHeaders, null, 4);
fs.writeFile(currentHeads, stringObj, function (err) {
if (err) {
return console.log(err);
}
});
});
});
});
It expects you to call next() for each directory, and you are calling it for each file found in the directory. So as soon as some directory contains 2 or more files, you get the error.
To fix it, try call next() on dive complete. See the dive documentation:
complete [optional] may define a second callback, that is called,
when all files have been processed. It takes no arguments.
dive(dir, {all: false}, function (err, file) {
if (err) {
return next(err);
} else {
// your file handling code here
}
}, function complete() {
next();
});
With the help of glortho in this thread i built this code:
for(var i=0;i<datos.length;i++){
bittrex.getticker(datos[i].Currency, function(err, data){
if (err){
console.log('ERROR:', err);
return 'ERROR:'+ err;
} else {
if (data.message!='INVALID_MARKET') {
this.LasValueBTC=data.result.Last;
} else {
this.LasValueBTC='';
}
}
}.bind(datos[i]));
}
The problem is that outside the callback function the datos array is not updated...As it is written at the moment if i console.log(this) inside the function works great and this.LastValueBTC exists in my json, but outside the function if i console.log(datos) after the loop, the LastValueBTC does not exist..and i need to do a res.send(datos) after the loop..
What you need to do is wait for all the callbacks to complete and then call res.send.
var count = datos.length;
for(var i=0;i<datos.length;i++){
bittrex.getticker(datos[i].Currency, function(err, data){
if (err){
console.log('ERROR:', err);
return 'ERROR:'+ err;
} else {
if (data.message!='INVALID_MARKET') {
this.LasValueBTC=data.result.Last;
} else {
this.LasValueBTC='';
}
count--;
if (count === 0) {
res.send(datos);
}
}
}.bind(datos[i]));
}
Or using async
async.each(datos, function(dato, next) {
bittrex.getticker(dato.Currency, function(err, data) {
if (err){
console.log('ERROR:', err);
next(err);
} else {
if (data.message!='INVALID_MARKET') {
dato.LasValueBTC = data.result.Last;
} else {
dato.LasValueBTC='';
}
next();
}
});
}, function(err) {
res.send(datos);
});
Go through this article http://www.richardrodger.com/2011/04/21/node-js-how-to-write-a-for-loop-with-callbacks/#.VTXnFa2eDGc
It gives a good conceptual overview on what happens if you put functions inside for loop
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);
});
});
}