I am trying to write an array of objects into a csv file in node.js. I have the following code:
fs=require('fs');
const data=[{name:'John'},{name:'Peter' }];
fs.writeFile('test.csv', data, 'utf8', function (err) {if (err)
{console.log('Some error occured - file either not saved or corrupted file saved.');
} else
{console.log('It\'s saved!');
}});
However when i open the saved csv file I have weird chinese characters only in the file. Would anyone have a clue what's going on here?
PS: I am on Windows; node version is 10.15.0
The data has to passed as a string - You can use JSON.stringify() to convert JavaScript Object(including Arrays) to a string.
https://nodejs.org/api/fs.html#fs_fs_writefile_file_data_options_callback
const fs = require('fs');
const data = [{name:'John'},{name:'Peter' }];
fs.writeFile('test.csv', JSON.stringify(data), 'utf8', function (err) {if (err)
{console.log('Some error occured - file either not saved or corrupted file saved.');
} else
{console.log('It\'s saved!');
}});
Note: From the data you are passing, this wouldn't be a csv file, most likely a JSON file.
Related
I call an API which returns a buffer data of a .zip file. I want to read files' buffer data which resides inside the .zip file using its buffer data without saving the .zip file. Is it possible?
Try the zlib library (its a core node.js library - docs: https://nodejs.org/api/zlib.html#zlib), with this example I took from the documentation
const {unzip } = require('node:zlib');
const buffer = Buffer.from('eJzT0yMAAGTvBe8=', 'base64');
unzip(buffer, (err, buffer) => {
if (err) {
console.error('An error occurred:', err);
process.exitCode = 1;
}
console.log(buffer.toString());
});
I am really new to node.js. I need to read .json files from a directory and then add them to an array and return it. I am able to read each file separately by passing the address:
const fs = require("fs");
fs.readFile("./fashion/customer.json", "utf8", (err, jsonString) => {
if (err) {
console.log("Error reading file from disk:", err);
return;
}
try {
const customer = JSON.parse(jsonString);
console.log("Customer address is:", customer.address); // => "Customer address is: Infinity Loop Drive"
} catch (err) {
console.log("Error parsing JSON string:", err);
}
});
But the same fashion folder has multiple json files. I want to add these files to an array and then return it. I tried using readdirSync but that just returned the file names. Is it possible to add json files to an array and return it?
Basically I require an array of this format:
Array[{contents of json file1}, {contents of json file2}, .....]
Any help is appreciated!
Here is a simple solution to your question:
const fs = require("fs");
const jsonFolder = './fashion'
var customerDataArray = []
fs.readdirSync(jsonFolder).forEach(file => {
let fileData = JSON.parse(fs.readFileSync(jsonFolder+'/'+file))
customerDataArray.push(fileData)
});
console.log(customerDataArray)
readdirSync returns an array with all the file names or objects in the directory. You can use forEach to iterate through every item in the array, which will be the file names in this scenario. To read the contents of each file, use readFileSync and specify the path to the file as the name of the directory plus the name of the file. The data is returned as a buffer and needs to be parsed using JSON.parse(), and then it is pushed to the customerDataArray.
I hope this answers your question!
I have a zip file that has a folder like
1234/pic1.png
1234/pic2.png
1234/data.xlsx
I am trying to extract the spreadsheet (failing that, all files) using node-stream-zip.
const StreamZip = require('node-stream-zip');
const zip = new StreamZip({
file: path.join(downloadsDir, fileToFind),
storeEntries: true
});
zip.on('ready', () => {
if(!fs.existsSync('extracted')) {
fs.mkdirSync('extracted');
}
zip.extract('1234/', './extracted', err => {
console.log(err);
});
zip.close();
});
This produces
EBADF: bad file descriptor, read
In the extracted folder is one of the png files. But when following the guide to extract just the xlsx file it appears that the xlsx file is the one causing this error.
zip.extract('1234/data.xlsx', './extracted.xlsx', err => {
console.log(err);
});
Is the problem with the xlsx file? I can open it manually. Is it permissions-related? Node? This particular package?
Your problem is related to zip.close(). You're closing it on the same tick as you're invoking zip.extract().
I'm using http.request to download JPEG file. I am then using fs.writeFile to try to write the JPEG file out to the hard drive.
None of my JPEG files can be opened, they all show an error (but they do have a file size). I have tried all of the different encodings with fs.writeFile.
What am I messing up in this process?
Here's what the working one is showing when viewing it raw:
And here is what the bad one using fs.writeFile is showing:
Figured it out, needed to use res.setEncoding('binary'); on my http.request.
Thank you, looking to the previous response, I was able to save de media correctly:
fs.writeFile(
filepath + fileName + extension,
mediaReceived, // to use with writeFile
{ encoding: "binary" }, // to use with writeFile ***************WORKING
(err) => {
if (err) {
console.log("An error ocurred while writing the media file.");
return console.log(err);
}
}
);
I am trying to save project and its file in GridFS. I want to save project first and using "_id" of project as metadata for file I want to save file. When i tried so i am getting ENOENT, open '/tmp/45e85388793de' error. here is my code
newProject.save(function (err,project) {
if (err) {
console.log('save error', err);
}
console.log("project added");
var id=poject._id;
var filepath = req.files.file.path;
var filename = req.files.file.name;
var writestream = gfs.createWriteStream({ filename: filename, metadata:id });
console.log(filepath);
fs.createReadStream(filepath)
.on('end', function() {
})
.on('error', function(err) {
console.log("error encountered"+err);//ENOENT,open error
})
.pipe(writestream);
});
Why i am getting this error and how to resolve it?
ENOENT in this context means "No such file or directory." It means the filepath you are trying to read with createReadStream does not exist.
I think you are getting this error since :
Your file is saved in a temporary location.
When you are inside the callback function your file is removed from that location and you are getting "No such file" error. Path and other variables still exists as part of js and that's why you are able to print them in console.
Solution:
Above(Outside) callback function move your file to some other permanent location using:
fs.rename(req.files.file.path, "./someKnownPath/filename");
Keep note of that location. In your callback function use the new location as path and try saving the file in gridfs. Once the file is saved you may delete it file from that location(/someKnownPath/filename).
This error was occuring for me as well. And the reason was temp directory was not in place. After I created manually and gave a try, it worked.
Now I have shifted to creating directory on the fly through node.js itself.