I was hoping I could get some advice on why my nodejs program is behaving in the way it is.
I am using two modules, node-sftp and node-inotify. I have setup node-inotify to watch a directory and call a function when something is written there, the function being an sftp upload.
Now the problem I have is that processing one file at a time is fine but when I drop 4 files in one go there, the function is called four times but only one sftp upload goes through.
Do I need to order my code in a particular way to ensure that the sftp upload occurs x times, is this something to do with closures perhaps?
This is a basic version of my code...
"event_handler" is called when something happens on a "watched" directory
"check_event" figures out if this type of event is one we want, in this case it's a "write"
"ftp_to_server" prepare connection details
"do_ftp" basically uses the node-sftp module to perform the sftp upload
event_handler = function(event){
var supplier;
check_event(event, supplier, type, ftp_to_server);
};
=================
function check_event(event, handler)
{
if (event.type === 'xxxxxx') {
var file_to_process_name = 'abc';
var file_to_process_dir = 'abc';
var remote_dir = 'abc';
handler(file_to_process_name, file_to_process_dir, remote_dir);
}
}
function ftp_to_server(file_to_process_name, file_to_process_dir, remote_dir) {
var connection_details = conf.ftp.connections
do_ftp(connection_details, file_to_process_name, file_to_process_dir, remote_dir);
}
function do_ftp(connection_details, file_to_process_name, file_to_process_dir, remote_dir) {
var credentials = {
// FTP settings here
};
var local_file = file_to_process_dir + file_to_process_name;
var remote_file = remote_dir + file_to_process_name;
connection = new sftp(credentials, function(err) {
if (err){
throw err;
}
connection.writeFile(remote_file, fs.readFileSync(local_file, "utf8"), null, function(err) {
if (err) {
throw err;
}
console.info('FTP PUT DONE');
});
});
};
Your "connection = new sftp(credentials, function(err) {"
should be
var connection = new sftp(credentials, function(err) {
The way you currently have it coded, "connection" is a global and you are writing over it.
Related
I use watson assistant v1
My problem is that every time I make a call to the code in Nodejs, where I return the context, to have a coordinated conversation, the context is only updated once and I get stuck in a node of the conversation
this is my code
client.on('message', message => {
//general variables
var carpetaIndividual = <../../../>
var cuerpoMensaje = <....>
var emisorMensaje = <....>
//detect if context exists
if(fs.existsSync(carpetaIndividual+'/contexto.json')) {
var watsonContexto = require(carpetaIndividual+'/contexto.json');
var variableContexto = watsonContexto;
} else {
var variableContexto = {}
}
//conection with Watson Assistant
assistant.message(
{
input: { text: cuerpoMensaje },
workspaceId: '<>',
context: variableContexto,
})
.then(response => {
let messageWatson = response.result.output.text[0];
let contextoWatson = response.result.context;
console.log('Chatbot: ' + messageWatson);
//Save and create JSON file for context
fs.writeFile(carpetaIndividual+'/contexto.json', JSON.stringify(contextoWatson), 'utf8', function (err) {
if (err) {
console.error(err);
}
});
//Send messages to my application
client.sendMessage(emisorMensaje, messageWatson)
})
.catch(err => {
console.log(err);
});
}
client.initialize();
the context.json file is updated, but when it is read the code only reads the first update of the context.json file and not the other updates
This will be because you are using require to read the .json file. For all subsequent requires of an already-required file, the data is cached and reused.
You will need to use fs.readfile and JSON.parse
// detect if context exists
if (fs.existsSync(carpetaIndividual+'/contexto.json')) {
var watsonContexto = fs.readFileSync(carpetaIndividual+'/contexto.json');
// Converting to JSON
var variableContexto = JSON.parse(watsonContexto);
} else {
var variableContexto = {}
}
There is another subtle problem with your code, in that you are relying on
your async call to fs.writeFile completing before you read the file. This will be the case most of the time, but as you don't wait for the fs.writeFile to complete there is the chance that you may try to read the file, before it is written.
I am running node.js on raspbian and trying to save/update a file every 2/3 seconds using the following code:
var saveFileSaving = false;
function loop() {
mainLoop = setTimeout(function() {
// update data
saveSaveFile(data, function() {
//console.log("Saved data to file");
loop();
});
}, 1500);
}
function saveSaveFile(data, callback) {
if(!saveFileSaving) {
saveFileSaving = true;
var wstream = fs.createWriteStream(path.join(__dirname, 'save.json'));
wstream.on('finish', function () {
saveFileSaving = false;
callback(data);
});
wstream.on('error', function (error) {
console.log(error);
saveFileSaving = false;
wstream.end();
callback(null);
});
wstream.write(JSON.stringify(data));
wstream.end();
} else {
callback(null);
}
}
When I run this it works fine for an hour then starts spitting out:
[25/May/2016 11:3:4 am] { [Error: EROFS, open '<path to file>']
errno: 56,
code: 'EROFS',
path: '<path to file>' }
I have tried jsonfile plugin which also sends out a similiar write error after an hour.
I have tried both fileSystem.writeFile and fileSystem.writeFileSync both give the same error after an hour.
I was thinking it had to do with the handler not being let go before a new save occurs which is why I started using the saveFileSaving flag.
Resetting the system via hard reset fixes the issue (soft reset does not work as the system seems to be locked up).
Any suggestions guys? I have searched the web and so only found one other question slightly similar from 4 years ago which was left in limbo.
Note: I am using the callback function from the code to continue with the main loop.
I was able to get this working by unlinking the file and saving the file every time I save while it is not pretty it works and shouldn't cause too much overhead.
I also added a backup solution which saves a backup every 5 minutes in case the save file has issues.
Thank you for everyone's help.
Here is my ideas:
1) Check free space when this problem happens by typing in terminal:
df -h
2) Also check if file is editable when problem occurs. with nano or vim and etc.
3) Your code too complicated for simply scheduling data manipulation and writing it to file. Because of even Your file will be busy (saveFileSaving) You will lose data until next iteration, try to use that code:
var
async = require('async'),
fs = require('fs'),
path = require('path');
async.forever(function(next) {
// some data manipulation
try {
fs.writeFileSync(path.join(__dirname, 'save.json'), JSON.stringify(data));
}
catch(ex) {
console.error('Error writing data to file:', ex);
}
setTimeout(next, 2000);
});
4) How about keeping file descriptor open?
var
async = require('async'),
fs = require('fs'),
path = require('path');
var file = fs.createWriteStream(path.join(__dirname, 'save.json'));
async.forever(function(next) {
// some data manipulation
file.write(JSON.stringify(data));
setTimeout(next, 2000);
});
var handleSignal = function (exc) {
// close file
file.end();
if(exc) {
console.log('STOPPING PROCESS BECAUSE OF:', exc);
}
process.exit(-1);
}
process.on('uncaughtException', handleSignal);
process.on('SIGHUP', handleSignal);
5) hardware or software problems (maybe because of OS drivers) with raspberry's storage controller.
I have uploaded a pdf via a MEAN stack web application using fs. I want to extract certain fields from the pdf and display them on the web app. I have looked at a couple npm packages like pdf.js, pdf2json. I can't figure out the documentation and javascript callbacks used in the examples available. Please help!
I hope I can help answer your question. Using pdf2json can be used to parse a pdf and extract the text. There are a couple of steps that need to be taken to get it working. I have adapted the example from https://github.com/modesty/pdf2json.
The setup is to install pdf2json in the node app, and also underscore. The example page didn't explain the need to define your own callback functions. It also used self instead of this to register them. So, with the appropriate changes the code to extract all the text from the pdf will be something like this:
// Get the dependencies that have already been installed
// to ./node_modules with `npm install <dep>`in the root director
// of your app
var _ = require('underscore'),
PDFParser = require('pdf2json');
var pdfParser = new PDFParser();
// Create a function to handle the pdf once it has been parsed.
// In this case we cycle through all the pages and extraxt
// All the text blocks and print them to console.
// If you do `console.log(JSON.stringify(pdf))` you will
// see how the parsed pdf is composed. Drill down into it
// to find the data you are looking for.
var _onPDFBinDataReady = function (pdf) {
console.log('Loaded pdf:\n');
for (var i in pdf.data.Pages) {
var page = pdf.data.Pages[i];
for (var j in page.Texts) {
var text = page.Texts[j];
console.log(text.R[0].T);
}
}
};
// Create an error handling function
var _onPDFBinDataError = function (error) {
console.log(error);
};
// Use underscore to bind the data ready function to the pdfParser
// so that when the data ready event is emitted your function will
// be called. As opposed to the example, I have used `this` instead
// of `self` since self had no meaning in this context
pdfParser.on('pdfParser_dataReady', _.bind(_onPDFBinDataReady, this));
// Register error handling function
pdfParser.on('pdfParser_dataError', _.bind(_onPDFBinDataError, this));
// Construct the file path of the pdf
var pdfFilePath = 'test3.pdf';
// Load the pdf. When it is loaded your data ready function will be called.
pdfParser.loadPDF(pdfFilePath);
I am running the code out of my server side controller.
module.exports = (function() {
return {
add: function(req, res) {
var tmp_path = req.files.pdf.path;
var target_path = './uploads/' + req.files.pdf.name;
fs.rename(tmp_path, target_path, function(err) {
if (err) throw err;
// delete the temporary file, so that the explicitly set temporary upload dir does not get filled with unwanted files
fs.unlink(tmp_path, function() {
if (err) throw err;
//edit here pdf parser
res.redirect('#/');
});
})
},
show: function(req, res) {
var pdfParser = new PDFParser();
var _onPDFBinDataReady = function (pdf) {
console.log('Loaded pdf:\n');
for (var i in pdf.data.Pages) {
var page = pdf.data.Pages[i];
// console.log(page.Texts);
for (var j in page.Texts) {
var text = page.Texts[j];
// console.log(text.R[0].T);
}
}
console.log(JSON.stringify(pdf));
};
// Create an error handling function
var _onPDFBinDataError = function (error) {
console.log(error);
};
pdfParser.on('pdfParser_dataReady', _.bind(_onPDFBinDataReady, this));
// Register error handling function
pdfParser.on('pdfParser_dataError', _.bind(_onPDFBinDataError, this));
// Construct the file path of the pdf
var pdfFilePath = './uploads/Invoice_template.pdf';
// Load the pdf. When it is loaded your data ready function will be called.
pdfParser.loadPDF(pdfFilePath);
},
//end controller
}
My problem seems to be the opposite of every node.js question :-) I have a simple forEach loop to read a list of files and insert them into a Couchbase database. This works great, but it never exits after reading all the lines. So I added a counter to shutdown the couchbase connection after all inserts are complete. This works.
This process is intended to load hundreds of thousands of files, so I brought the async module into the mix to batch the inserts into groups of 100. The async.eachLimit is used to iterate over the array and insert documents in batches. Now the orig problem is back. Whatever magic async.eachLimit uses to recognize the process is complete is not happening.
I've been going through javascript scoping, callbacks, async, etc. Google searches are hitting keywords but not this issue. I've reduced the code down to the following testcase. To test, create three files and add their names to testlist.txt.
The async.eachLimit in place works up until it hits the limit, then hangs. Comment this out and uncomment array.forEach line and it works. Thanks in advance!
var fs = require('fs');
var couchbase = require('couchbase');
var async = require('async');
var filelist = 'testlist.txt';
var key_count = 0;
var cb_config = { host: 'localhost:8091', bucket: 'default'};
var db = new couchbase.Connection(cb_config, function(err) {
if (err) {
console.log('ERRR connect to couchbase at config['+cb_config+']');
throw err;
}
});
var insertFile=function(line) {
console.log('LOAD ['+line+']');
fs.readFile(line, function(file_err, f_doc) {
if(file_err) throw file_err;
db.set(line, f_doc, function(db_err, db_res){
if (db_err) {
console.log('FAIL ['+line+'] err['+db_err+']');
} else {
console.log('PASS ['+line+']');
}
key_count--;
if (key_count == 0) {
console.log('DONE Shutting down client, no more keys');
db.shutdown();
}
});
});
}
// read list of files into data array from file filelist
fs.readFile(filelist, function(filelist_err, lines) {
if(filelist_err) throw filelist_err;
// HACK split adds empty line to array, use replace to fix
var array = lines.toString().replace(/\n$/, '').split('\n');
key_count = array.length;
console.log('INIT lines['+key_count+']');
async.eachLimit(array, 2, insertFile, function(err) { console.log('FAIL async err['+err+']');} );
//array.forEach(function(data){insertFile(data);return;});
});
Testcase output using array.forEach:
INIT lines[3]
LOAD [files.big.txt]
LOAD [files.little.txt]
LOAD [files.txt]
PASS [files.little.txt]
PASS [files.big.txt]
PASS [files.txt]
DONE Shutting down client, no more keys
Testcase output using async.eachLimit:
INIT lines[3]
LOAD [files.big.txt]
LOAD [files.little.txt]
PASS [files.little.txt]
PASS [files.big.txt]
... hang, never gets to 3...
After review with a coworker, they spotted my mistake. I missed the async callback in my insertFile function. Adding that in works and allows me to remove the key counter! Solution code below:
var fs = require('fs');
var couchbase = require('couchbase');
var async = require('async');
var filelist = 'testlist.txt';
var key_count = 0;
var cb_config = { host: 'localhost:8091', bucket: 'default'};
var db = new couchbase.Connection(cb_config, function(err) {
if (err) {
console.log('ERRR connect to couchbase at config['+cb_config+']');
throw err;
}
});
var insertFile=function(line, callback) {
console.log('LOAD ['+line+']');
fs.readFile(line, function(file_err, f_doc) {
if(file_err) throw file_err;
db.set(line, f_doc, function(db_err, db_res){
if (db_err) {
console.log('FAIL ['+line+'] err['+db_err+']');
callback(db_err);
} else {
console.log('PASS ['+line+']');
callback();
}
});
});
}
// read list of files into data array from file filelist
fs.readFile(filelist, function(filelist_err, data) {
if(filelist_err) throw filelist_err;
// HACK stoopid bug split adds empty line to array, use replace to fix
var array = data.toString().replace(/\n$/, '').split('\n');
key_count = array.length;
console.log('READ files['+key_count+']');
async.eachLimit(array, 2, insertFile, function(err) {
if (err) console.log('LAST with async err['+err+']');
console.log('DONE Shutting down client, no more keys');
db.shutdown();
});
});
And successful output:
$ node testcase.js
READ files[3]
LOAD [files.big.txt]
LOAD [files.little.txt]
PASS [files.little.txt]
LOAD [files.txt]
PASS [files.big.txt]
PASS [files.txt]
DONE Shutting down client, no more keys
I'm new to NodeJS and I wonder how to properly send the content of several files using FS and Socket.IO.
My problem is more about best practices on Node/javascript than the actual 'raw' logic of my scripts.
So, the purpose of my app is to watch a log File (File1.log) and a Result File (File2.log).
Until the File2.log contains a string (such as "Done", or "Error"), I need to continue sending the result of the File1.log to the client.
When the key ("Error","Done") has been read, I send the result to the client and have to launch the same process for another couple of log/result files - after having closed the FileWatcher on the first one.
In the end, I need to close the connection and stop all of the sleeping FileWatcher processes.
The 'streaming' of my files is working pretty well, but I am confused about the best way to switch between the differents FileWatch Processes and how to notify the client.
Server.JS
/*
* [SomeCode]...
*/
io.sockets.on('connection', function (client) {
//Starting the process for the first couple of files
client.on('logA', function (res) {
var PATH_to_A = "path/to/A/directory/";
readFile(client,PATH_to_A);
});
//Starting the process for the seconde couple of files
client.on('logB', function (res) {
//I need to stop the first readFile Watcher process
var PATH_to_B = "path/to/B/directory/";
readFile(client,PATH_to_B);
});
});
function readFile(client,PATH){
var File1 = path.join(PATH,'File1.log');
var File2 = path.join(PATH,'File2.log');
//Get the file stats
fs.stat(File1,function(err,stats){
if (err) throw err;
//Send the data;
});
//Watch the first file
var w1 = fs.watch(File1,function(status, file){
if(status == "change"){
fs.stat(File1,function(err,stats){
if (err) throw err;
//Send the data;
});
}
});
//Watch the second file
var w2 = fs.watch(File2,function(status, file){
if(status == "change"){
fs.readFile(File2, "utf8", function (err, body) {
if (err) throw err;
//Some Code....
client.emit('done',body);
});
}
});
//Closing FileWatcher
client.on('ack',function(){
w1.close();
w2.close();
});
}
Client.JS
var socket = io.connect('http://127.0.0.1:8000');
//On connect, waiting for the first couple of files
socket.on('connect', function(server) {
socket.emit('init',data);
socket.emit('logA');
});
//If the first process is done, i ask for the second couple of files
socket.on('done',function(message){
socket.emit('ack');
socket.emit('logB');
});
Thanks for your help!