I have no idea how to ask this but it seems to be a fairly simple thing.
In this gulp task every occurrence of "old" is replaced with "new" on a bunch of files.
gulp.task('prefix-replace', function () {
return gulp.src('svg/*')
.pipe(replace('old', 'new'))
.pipe(gulp.dest('dist/'));
});
How to get the name of the file (or index or any unique id), so replacements would have a unique prefix for each file?
I tried with uuid:
gulp.task('prefix-replace', function () {
return gulp.src('svg/*')
.pipe(replace('old', uuidv4() + 'new'))
.pipe(gulp.dest('dist/'));
});
But this generates the SAME id for every replacement in all files (I know that's not a for loop but I'm struggling with streams at the moment as you can clearly see).
This will generate a new id for EVERY replacement, which is also not what I'm looking for:
gulp.task('prefix-replace', function () {
return gulp.src('svg/*')
.pipe(replace('term', function() {
return uuidv4() + 'term'
}))
.pipe(gulp.dest('dist/'));
});
How to get a unique id for each file?
gulp-replace with file object does have access to a vinyl file reference which you can use to get the current file name like so:
gulp.task('prefix-replace', function () {
return gulp.src('svg/*')
.pipe(replace('term', function() {
return this.file.relative + ': term'
}))
.pipe(gulp.dest('dist/'));
});
this.file.relative is a string so you can use string operations on it if need be (such as stripping off the extension). this.file.path gives you the full path to the current file.
The gulp-rename package has a prefix option https://www.npmjs.com/package/gulp-rename
Related
So I use this API that helps me turn a .docx file into a .pdf. I placed the code that converts the file into a function. :
function conv(){
convertapi.convert('pdf', { File: final_path })
.then(function(result) {
// get converted file url
console.log("Converted file url: " + result.file.url);
finp = path + file_name.slice(0, file_name.length - 5) + ".pdf";
console.log(finp);
// save to file
return result.file.save(finp);
})
.then(function(file) {
console.log("File saved: " + file);
process.exit(1);
})
.catch(function(e) {
console.log("numele si/sau extensia fisierului sunt gresite");
process.exit(1);
});
}
The code above works only for one file at a time. I made a loop that goes through every file (.docx) in my folder and save its name into an array. I go through every item of the array and call the function :
for(var j = 0; j<=i ; j++){
file_name = toate_nume[j];
final_path = path + file_name;
conv();
}
The file names are stored correctly, but when I run my project, the function is called after the loop itself ends ( is called the correct number of times for each and every file). So if I have 2 files : test1.docx and test2.docx the output shows me that the conv() is called 2 times for the test2.docx, instead of one time for each file. What should I do?
The reason might be this:
The API is slow so your program is executing the loop faster than the API the can handle the requests. So what ends up happening is that you have modified the final_path variable twice before convertapi gets called, and then it gets called twice with the same final_path. Try to modify your conv function so that it accepts a parameter, e.g. path and uses that. Then call conv with the current final_path parameter:
conv(final_path)
And:
function conv(path) {
convertapi.convert('pdf', { File: path })
...
So you are calling n Promise in a serial. And you want to wait for the end?
You can use Promise. all
const toate_nume = ['fileName1', 'fileName2'];
const spawn = toate_nume.map(x => {
const final_path = path + x;
return conv(final_path);
});
Promise.all(spawn).then(results => {
console.log('All operation done successfully %o', results);
});
or use await:
const results = await Promise.all(spawn);
the results is an array, an entry for each call.
NOTE** I pass the path as an argument instead of a global var
I am trying to filter files through node ncp library but it its filter is not working.
Once the filter gets false return it breaks the whole copying process
ncp(source, destination, options, function (err) {
if (err) {
console.error("backup error:", err);
}
console.log("Backup of done!');
});
var options = {
filter: function (file) {
console.log("copying file:", file);
var res = file.toString().indexOf("\\testdrive") !== -1;
console.log("res:", res);
return !res;
},
//filter: new RegExp("\\testdrive"),//Or RegEx intance
};
So once the filter function or RegEx instance gets false result the whole copy break
options.filter - a RegExp instance, against which each file name is tested to determine whether to copy it or not, or a function taking single parameter: copied file name, returning true or false, determining whether to copy file or not.
Just found the solution:
Seems like the filter RegExp/function will not only be called for the filenames that ncp is supposed to copy, but also for the foldernames.
The first foldername it filters is apparently the one you passed to ncp as source. And if that fails, ncp just stops copying anything in that folder.
See: https://github.com/AvianFlu/ncp/issues/130
For those coming late to the party (like me):
ncp traverse dir tree in a way that directory full paths are subjected to filter as well, on top of that, source directory itself is tested as well. In my case I wanted to copy bunch (lets call them one.svg, zwei.svg, tres.svg) of SVG files from single level directory called images, which resulted in following code:
ncp(srcImages, outImages, { filter: /.*(images|one\.svg|zwei\.svg|tres\.svg)$/ }, err => {
if (err) return console.error(err);
console.log('done!')
});
PS: please note that there is $ on the end of the regex meaning that we try to match end of the string
I have been trying to make one of my gulp task work, but can't figure out how to use the gulp-tap for my specific case.
I want to take the filename of the current processed amp-html file and use it to import the css file with the same name into the file.
Current incomplete task :
gulp.task('build:html', function () {
return gulp.src(SOURCE_PATH+AMP_FILES)
.pipe(htmlreplace({
'cssInline': {
'src': gulp.src(TMP_PATH + *CURRENT-AMP-FILENAME* + '.css'),
'tpl': '<style amp-custom>%s</style>'
}
}))
.pipe(gulp.dest(BUILD_PATH));
});
One of my many tries (simplified) :
gulp.task('build:html', function () {
return gulp.src(SOURCE_PATH+AMP_FILES)
.pipe(tap(function(file, t) {
var filename = path.basename(file.path);
return t
.pipe(htmlreplace({
'cssInline': {
'src': gulp.src(TMP_PATH+filename + '.css'),
'tpl': '<style amp-custom>%s</style>'
}
}));
}))
.pipe(gulp.dest(BUILD_PATH));
});
How can I make it work with gulp-tap ? I actually don't understand how to pick-up the stream and tried in so many ways...
Thank you in advance for your help
I am not sure where I am going wrong but I think that the event listener is getting invoked multiple times and parsing the files multiple times.
I have five files in the directory and they are getting parsed. However the pdf file with array 0 gets parsed once and the next one twice and third one three times.
I want the each file in the directory to be parsed once and create a text file by extracting the data from pdf.
The Idea is to parse the pdf get the content as text and convert the text in to json in a specific format.
To make it simple, the plan is to complete one task first then use the output from the below code to perform the next task.
Hope anyone can help and point out where i am going wrong and explain a bit about my mistake so i understand it. (new to the JS and Node)
Regards,
Jai
Using the module from here:
https://github.com/modesty/pdf2json
var fs = require('fs')
PDFParser = require('C:/Users/Administrator/node_modules/pdf2json/PDFParser')
var pdfParser = new PDFParser(this, 1)
fs.readdir('C:/Users/Administrator/Desktop/Project/Input/',function(err,pdffiles){
//console.log(pdffiles)
pdffiles.forEach(function(pdffile){
console.log(pdffile)
pdfParser.once("pdfParser_dataReady",function(){
fs.writeFile('C:/Users/Administrator/Desktop/Project/Jsonoutput/'+pdffile, pdfParser.getRawTextContent())
pdfParser.loadPDF('C:/Users/Administrator/Desktop/Project/Input/'+pdffile)
})
})
})
As mentioned in the comment, just contributing 'work-around' ideas for OP to temporary resolve this issue.
Assuming performance is not an issue then you should be able to asynchronously parse the pdf files in a sequential matter. That is, only parse the next file when the first one is done.
Unfortunately I have never used the npm module PDFParser before so it is really difficult for me to try the code below. Pardon me as it may require some minor tweaks to make it to work, syntactically they should be fine as they were written using an IDE.
Example:
var fs = require('fs');
PDFParser = require('C:/Users/Administrator/node_modules/pdf2json/PDFParser');
var parseFile = function(files, done) {
var pdfFile = files.pop();
if (pdfFile) {
var pdfParser = new PDFParser();
pdfParser.on("pdfParser_dataError", errData => { return done(errData); });
pdfParser.on("pdfParser_dataReady", pdfData => {
fs.writeFile("'C:/Users/Administrator/Desktop/Project/Jsonoutput/" + pdfFile, JSON.stringify(pdfData));
parseFile(files, done);
});
pdfParser.loadPDF('C:/Users/Administrator/Desktop/Project/Input/' + pdfFile);
}
else {
return done(null, "All pdf files parsed.")
}
};
fs.readdir('C:/Users/Administrator/Desktop/Project/Input/',function(err,pdffiles){
parseFile(pdffiles, (err, message) => {
if (err) { console.error(err.parseError); }
else { console.log(message); }
})
});
In the code above, I have isolated out the parsing logic into a separated function called parseFile. In this function it first checks to see if there are still files to process or not, if none then it invokes the callback function done otherwise it will do an array.pop operation to get the next file in queue and starts parsing it.
When parsing is done then it recursively call the parseFile function until the last file is parsed.
We have a buffer we'd like to write to a file. If the file already exists, we need to increment an index on it, and try again. Is there a way to create a file only if it doesn't exist, or should I just stat files until I get an error to find one that doesn't exist already?
For example, I have files a_1.jpg and a_2.jpg. I'd like my method to try creating a_1.jpg and a_2.jpg, and fail, and finally successfully create a_3.jpg.
The ideal method would look something like this:
fs.writeFile(path, data, { overwrite: false }, function (err) {
if (err) throw err;
console.log('It\'s saved!');
});
or like this:
fs.createWriteStream(path, { overwrite: false });
Does anything like this exist in node's fs library?
EDIT: My question isn't if there's a separate function that checks for existence. It's this: is there a way to create a file if it doesn't exist, in a single file system call?
As your intuition correctly guessed, the naive solution with a pair of exists / writeFile calls is wrong. Asynchronous code runs in unpredictable ways. And in given case it is
Is there a file a.txt? — No.
(File a.txt gets created by another program)
Write to a.txt if it's possible. — Okay.
But yes, we can do that in a single call. We're working with file system so it's a good idea to read developer manual on fs. And hey, here's an interesting part.
'w' - Open file for writing. The file is created (if it does not
exist) or truncated (if it exists).
'wx' - Like 'w' but fails if path exists.
So all we have to do is just add wx to the fs.open call. But hey, we don't like fopen-like IO. Let's read on fs.writeFile a bit more.
fs.readFile(filename[, options], callback)#
filename String
options Object
encoding String | Null default = null
flag String default = 'r'
callback Function
That options.flag looks promising. So we try
fs.writeFile(path, data, { flag: 'wx' }, function (err) {
if (err) throw err;
console.log("It's saved!");
});
And it works perfectly for a single write. I guess this code will fail in some more bizarre ways yet if you try to solve your task with it. You have an atomary "check for a_#.jpg existence, and write there if it's empty" operation, but all the other fs state is not locked, and a_1.jpg file may spontaneously disappear while you're already checking a_5.jpg. Most* file systems are no ACID databases, and the fact that you're able to do at least some atomic operations is miraculous. It's very likely that wx code won't work on some platform. So for the sake of your sanity, use database, finally.
Some more info for the suffering
Imagine we're writing something like memoize-fs that caches results of function calls to the file system to save us some network/cpu time. Could we open the file for reading if it exists, and for writing if it doesn't, all in the single call? Let's take a funny look on those flags. After a while of mental exercises we can see that a+ does what we want: if the file doesn't exist, it creates one and opens it both for reading and writing, and if the file exists it does so without clearing the file (as w+ would). But now we cannot use it neither in (smth)File, nor in create(Smth)Stream functions. And that seems like a missing feature.
So feel free to file it as a feature request (or even a bug) to Node.js github, as lack of atomic asynchronous file system API is a drawback of Node. Though don't expect changes any time soon.
Edit. I would like to link to articles by Linus and by Dan Luu on why exactly you don't want to do anything smart with your fs calls, because the claim was left mostly not based on anything.
What about using the a option?
According to the docs:
'a+' - Open file for reading and appending. The file is created if it does not exist.
It seems to work perfectly with createWriteStream
This method is no longer recommended. fs.exists is deprecated. See comments.
Here are some options:
1) Have 2 "fs" calls. The first one is the "fs.exists" call, and the second is "fs.write / read, etc"
//checks if the file exists.
//If it does, it just calls back.
//If it doesn't, then the file is created.
function checkForFile(fileName,callback)
{
fs.exists(fileName, function (exists) {
if(exists)
{
callback();
}else
{
fs.writeFile(fileName, {flag: 'wx'}, function (err, data)
{
callback();
})
}
});
}
function writeToFile()
{
checkForFile("file.dat",function()
{
//It is now safe to write/read to file.dat
fs.readFile("file.dat", function (err,data)
{
//do stuff
});
});
}
2) Or Create an empty file first:
--- Sync:
//If you want to force the file to be empty then you want to use the 'w' flag:
var fd = fs.openSync(filepath, 'w');
//That will truncate the file if it exists and create it if it doesn't.
//Wrap it in an fs.closeSync call if you don't need the file descriptor it returns.
fs.closeSync(fs.openSync(filepath, 'w'));
--- ASync:
var fs = require("fs");
fs.open(path, "wx", function (err, fd) {
// handle error
fs.close(fd, function (err) {
// handle error
});
});
3) Or use "touch": https://github.com/isaacs/node-touch
Todo this in a single system call you can use the fs-extra npm module.
After this the file will have been created as well as the directory it is to be placed in.
const fs = require('fs-extra');
const file = '/tmp/this/path/does/not/exist/file.txt'
fs.ensureFile(file, err => {
console.log(err) // => null
});
Another way is to use ensureFileSync which will do the same thing but synchronous.
const fs = require('fs-extra');
const file = '/tmp/this/path/does/not/exist/file.txt'
fs.ensureFileSync(file)
With async / await and Typescript I would do:
import * as fs from 'fs'
async function upsertFile(name: string) {
try {
// try to read file
await fs.promises.readFile(name)
} catch (error) {
// create empty file, because it wasn't found
await fs.promises.writeFile(name, '')
}
}
Here's a synchronous way of doing it:
try {
await fs.truncateSync(filepath, 0);
} catch (err) {
await fs.writeFileSync(filepath, "", { flag: "wx" });
}
If the file exists it will get truncated, otherwise it gets created if an error is raised.
This works for me.
// Use the file system fs promises
const {access} = require('fs/promises');
// File Exist returns true
// dont use exists which is no more!
const fexists =async (path)=> {
try {
await access(path);
return true;
} catch {
return false;
}
}
// Wrapper for your main program
async function mainapp(){
if( await fexists("./users.json")){
console.log("File is here");
} else {
console.log("File not here -so make one");
}
}
// run your program
mainapp();
Just keep eye on your async - awaits so everthing plays nice.
hope this helps.
You can do something like this:
function writeFile(i){
var i = i || 0;
var fileName = 'a_' + i + '.jpg';
fs.exists(fileName, function (exists) {
if(exists){
writeFile(++i);
} else {
fs.writeFile(fileName);
}
});
}