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Unable to remove data from json file on disk

I'm unable to find a way to remove whole line of JSON data(line) after it's used.
For some reason delete is not working or rather said not doing anything.
.JSON
[
{"id":"1","code":"super-S","expires_in":"","gives_currencies":"1.5","gives_items":"","number_of_attempts":"1","attempts_used":""},
{"id":"2","code":"wow!","expires_in":"","gives_currencies":"3","gives_items":"","number_of_attempts":"1","attempts_used":""},
{"id":"3","code":"slashme","expires_in":"","gives_currencies":"4","gives_items":"","number_of_attempts":"1","attempts_used":""},
{"id":"4","code":"randombla","expires_in":"","gives_currencies":"5","gives_items":"","number_of_attempts":"1","attempts_used":""}
]
code
//fs configuration
const fs = require('fs');
let rawdata = fs.readFileSync('test.json');
let mycodes = JSON.parse(rawdata);
//something above
const randomcode = mycodes[Math.floor(Math.random() * mycodes.length)];
console.log('Your code is:', randomcode['code']); //logs me a random code value
delete mycodes[randomcode];
The goal here is to select random code, which is done but then I need to remove it from .JSON file so it won't repeat. I tried several things but it's not working, delete.randomcode etc... the line never removed from the .JSON file.

Use Array.prototype.splice(index, deleteCount) instead of delete.
delete, on an Array, will just null the key, without removing it.
Save back your modified data using JSON.stringify(mycodes) to that same file.
const fs = require('fs');
const mycodes = JSON.parse(fs.readFileSync('./test.json'));
const randomIndex = Math.floor(Math.random() * mycodes.length);
const randomObject = mycodes[randomIndex];
console.log('Your code is:', randomObject.code); // Log a random code value
mycodes.splice(randomIndex, 1); // Remove one key at randomIndex
// Write back to file
fs.writeFileSync('test.json', JSON.stringify(mycodes, 0, 4), 'utf8');
If you already have that Object out of your Array, and since Objects are passed by reference (like pointer in memory), make use of the Array.prototype.indexOf(someObject) like:
const fs = require('fs');
const mycodes = JSON.parse(fs.readFileSync('./test.json'));
const randomIndex = Math.floor(Math.random() * mycodes.length);
const randomObject = mycodes[randomIndex];
// later in your code....
const objIndex = mycodes.indexOf(randomObject); // Get Object index in Array
mycodes.splice(objIndex, 1); // Remove it from array at that index
// Write back to file
fs.writeFileSync('test.json', JSON.stringify(mycodes, 0, 4), 'utf8');

You need to persist your data by writing it back to your JSON file after using JSON.stringify().
While you're at it, you can move your code into functions, which will make it easier to read and work with.
You might also want to read about editing arrays using Array.prototype.splice().
The delete operator is for deleting properties from objects. While you can use it to delete elements from an array, it will leave the index empty rather than closing the gap in the array after deletion.
const fs = require('fs');
// get a random element from any array
function getRandomElement (array) {
const randomElement = array[Math.floor(Math.random() * array.length)];
return randomElement;
}
function deleteElementFromArray (array, element) {
const index = array.indexOf(element);
if (index < 0) return false;
array.splice(index, 1);
return true;
}
// move the reading work inside a function
function readJson (filePath) {
const json = fs.readFileSync(filePath, {encoding: 'utf8'});
const data = JSON.parse(json);
return data;
}
// move the reading work inside a function
function writeJson (filePath, data) {
const json = JSON.stringify(data);
fs.writeFileSync(filePath, json);
}
const jsonFilePath = 'test.json';
const mycodes = readJson(jsonFilePath);
const randomcode = getRandomElement(mycodes);
console.log('Your code is:', randomcode['code']);
deleteElementFromArray(mycodes, randomcode);
writeJson(jsonFilePath, mycodes);

Problems with nested Object.keys forEach loop and building array of merged JSON objects

I have two CSV files, one with routing steps and one with a list of ids. I need to add each id to the start of each routing step. I'm using Node.js.
var routeNumFile = '/routing_numbers.csv';
var routeStepFile = '/routing_steps.csv';
const csvToJson = require('csvtojson');
const jsonToCsv = require('json2csv').parse;
const fs = require('fs');
var routeNumArray;
var routeStepArray;
try {
routeNumArray = await csvToJson().fromFile(routeNumFile);
} catch (err) {
console.log("error in reading csv file")
}
try {
routeStepArray = await csvToJson().fromFile(routeStepFile);
} catch (err) {
console.log("error in reading csv file")
}
var outputArray = new Array;
var outputPath = '/gitlab/BSI_Create_Csv_Import/finalOutput.csv';
if (routeNumArray != null && routeStepArray != null) {
Object.keys(routeNumArray).forEach(function (key1) {
Object.keys(routeStepArray).forEach(function (key2) {
var comboObj = Object.assign(routeNumArray[key1], routeStepArray[key2]);
console.log(comboObj);
outputArray.push(comboObj);
});
});
}
console.log(outputArray);
var csv = jsonToCsv(outputArray);
fs.writeFileSync(outputPath, csv);
The output from console.log(comboObj) is what I want. However, when I put that into an array, I just get the very last entry in the routing steps CSV over and over. If I write it using a stream directly where the comboObj is created, it mostly works. If I do that I convert the object to CSV first and the output leaves me with the headings duplicated at the end of every line. It writes much cleaner from an array of JSON objects to a CSV.
So, I'm trying to get all of the combined objects together in an array so I can convert it all to CSV and write it to a file. Can anyone tell me what's going wrong with my method?

You should create a new object and assign properties to it, like this:
var comboObj = Object.assign({}, routeNumArray[key1], routeStepArray[key2]);

Nodejs Convert text to JSON

For some reason I'm having such a hard time converting this txt file to an actual javascript array.
myJson.txt
{"action": "key press", "timestamp": 1523783621, "user": "neovim"}
{"action": "unlike", "timestamp": 1523784584, "user": "r00k"}
{"action": "touch", "timestamp": 1523784963, "user": "eevee"}
{"action": "report as spam", "timestamp": 1523786005, "user": "moxie"}
Currently what I have that doesn't work
const fs = require('fs');
function convert(input_file_path) {
const file = fs.readFileSync(input_file_path, 'utf8');
const newFormat = file
.replace(/(\r\n\t|\n|\r\t)/gm,'')
.replace(/}{/g, '},{');
console.log([JSON.parse(newFormat)]);
}
convert('myJson.txt');

Since your file contains a JSON object per line, you could read that file line by line, using readline.
Each line is then parsed, and push into an array, which is then returned (resolved) after the file is fully read.
'use strict';
const fs = require('fs');
const readline = require('readline');
function convert(file) {
return new Promise((resolve, reject) => {
const stream = fs.createReadStream(file);
// Handle stream error (IE: file not found)
stream.on('error', reject);
const reader = readline.createInterface({
input: stream
});
const array = [];
reader.on('line', line => {
array.push(JSON.parse(line));
});
reader.on('close', () => resolve(array));
});
}
convert('myJson.txt')
.then(res => {
console.log(res);
})
.catch(err => console.error(err));

I would have done this in this way
var fs = require('fs');
var readline = require('readline');
var array = [];
var input = null;
var rd = readline.createInterface({
input: fs.createReadStream(__dirname+'/demo.txt')
});
rd.on('line', function(line) {
array.push(JSON.parse(line));
});
rd.on('close', function(d){
array.forEach(e=>console.log(e.action))
})
What's happening here is, I am reading the lines of the file on by one using readline which is one of the core modules of nodejs. Listening on the events and doing what needed.
And yeah, you'll have to parse the line to JSON for sure ;)
Thanks

The problem with your code is that you're trying to parse JS array as JSON array. while JSON array string should be only string.
Here what you're trying to do:
jsArray = ['{"foo": "bar"}, {"foo":"baz"}']
This is a valid JS array of a single string value '{"foo": "bar"}, {"foo":"baz"}'.
while
jsonArrayStr = '["{"foo": "bar"}, {"foo":"baz"}"]'
This is a valid JSON array string (as the square brackets is part of the string).
So as to get your code running, you need to add the square brackets to your string before parsing it.
function convert(input_file_path) {
const file = fs.readFileSync(input_file_path, 'utf8');
const newFormat = file
.replace("{", "[{")
.replace(/}$/, "}]")
console.log(JSON.parse('[' + newFormat + ']'));
}

What I'm doing in the script is reading the content of text file line by line and storing it to array along with converting it to JSON object. When we reach last line and our JSON array/object has all the data. Now you can write this object to a new file fs.writeFileSync() after converting JSON object to string with JSON.stringify().
Note :- You've to install Line reader package i.e. npm install line-reader
var lineReader = require('line-reader');
var fs = require('fs')
var jsonObj = {};
var obj = [];
var file = "fileName.json"
var num= 0;
lineRead();
async function lineRead(){
lineReader.eachLine('input.txt', function(line, last) {
// to check on which line we're.
console.log(num);
num++;
convertJson(line)
if(last){
//when it's last line we convert json obj to string and save it to new file.
var data = JSON.stringify(obj)
fs.writeFileSync(file,data);
}
});
}
function convertJson(data){
var currentVal = data
var value = JSON.parse(data)
var temp = value;
//storing the value in json object
jsonObj = value;
obj.push(jsonObj);
}
}

get specific file content via node js

I use the following code to get specific file which is located in my c folder,
my question is how to get specific content inside this file for example
i've text file and the content is
name:test 1 test2 test 3
user: foo bar
I need that when the file was read to get the test1 test2 test3 as "string" when I find "key" of name in the text file.
How can I do that ?
fs = require('fs')
fs.readFile('c//myfile.txt', 'utf8', function (err,data) {
if (err) {
return console.log(err);
}
});

The other answer will have issues when your value contains ':'.
For example when your line is 'name: bla:bli:blub', you would only get 'bla' as a result.
So this is my suggestion that wont have that problem:
You could place this snippet into your readFile method:
var keyValueObject = {};
data.split("\n").forEach(function(element) {
var keyValueSeperatorPosition = element.indexOf(':');
var key = element.substr(0, keyValueSeperatorPosition);
var value = element.substring(keyValueSeperatorPosition + 1);
keyValueObject[key] = value;
});
You can then access your values using:
keyValueObject['name']

EDIT1:
done it a little more generic now. keyVals is now an array of objects with key and val pairs of your file
fs = require('fs')
var keyVals = [];
fs.readFile('c//myfile.txt', 'utf8', function (err,data) {
if (err) {
return console.log(err);
}
var lines = data.split('\n');
lines.forEach(function(line){
var pair = line.split(':');
keyVals.push({key:pair[0],val:pair[1]});
});
});
access it like this:
keyVals.forEach(function(element){
console.log(element.key, element.value);
})
I hope this helps

python to node.js confusion

So I have this python code that I'm trying to convert to node.js, but I am not sure how.
import urllib.request, re
def getDef(word):
link = "http://www.merriam-webster.com/dictionary/%s" % word
data = urllib.request.urlopen(link).read().decode()
try:
return re.search("<p>: (.*?)</p><p>", data).group(1)
except:
return "No match"
class newDefinition:
def __init__(self, word):
self.definition = getDef(word);
>>> definition = newDefintion("color")
>>> print(definition.definition)
a quality such as red, blue, green, yellow, etc., that you see when you look at something
In node.js however though it I can seem to return it like in python because of it's callback way of doing things, or at least I can't seem to return it which is why I'm asking how would I do the node.js equivalent or is their no equivalent? Here is what I have so far maybe you can spot what I'm doing wrong and how to fix it
var urllib = require("urllib"); // installed with npm
var getDef = function(word){
var link = "http://www.merriam-webster.com/dictionary/" + word;
var urlData = urllib.request(link, {}, function(err, data, res){
var re = new RegExp("<p>: (.*?)</p><p>");
var results = data.toString();
var match = re.exec(results)[1];
return match; // Expected it to give urlData the definition
});
return urlData;
}
var Definition = function(word){
this.definition = getDef(word);
}
definition = new Definition("color");
console.log(definition.definition); // this won't give the definition but the information of the urllib itself rather.
So in general trying to figure out is how to use asynchronous code so I can return things that I need, but I am not use to this concept either so is there an equivalent to this in python? Also if you can point me to some good documentation on asynchronous code that would be great also.

Since return will actually just exit your function instead of returning a value, you need to use a callback. It would look like this:
var urllib = require("urllib");
var getDef = function(word, callback){
var link = 'http://www.merriam-webster.com/dictionary/' + word;
urllib.request(link, {}, function(err, data, res) {
var re = new RegExp('<p>: (.*?)</p><p>');
var results = data.toString();
var match = re.exec(results)[1];
callback(match);
});
};
Then you would pass a callback while calling the function:
getDef('color', function(definition) {
console.log(definition);
});
Edit: Setting an object's property has the same idea. It might look like this instead:
var Definition = function(word) {
var self = this;
getDef(world, function(definition, callback) {
self.definition = definition;
callback.call(self);
});
};
And would be called like so:
var definition = new Definition('color', function() {
console.log(definition.definition);
});

Here is my two cent worth suggestion.
Never ever use regular expressions to parse HTML (Refer here for more details), instead use the XPath like library to parse the document. You can use libraries like cheerio or phantomjs.
Here is a clean solution.
var request = require('request'),
when = require('when'),
cheerio = require('cheerio');
var URL = 'http://www.merriam-webster.com/dictionary/';
/**
* #param word: Word to search the dictionary
* #returns
* Promise object which resolves to array of
* definitions of the word
*/
var getDef = function(word){
var defer = when.defer();
request(URL + word, function(err, res, body){
if (err || res.statusCode !== 200){
defer.reject();
}
var defs = [];
var $ = cheerio.load(body);
$('.wordclick .headword:first-child p').each(function(i,ele){
var definition = $(ele).text();
defs.push(definition);
});
defer.resolve(defs);
});
return defer.promise;
}
getDef('happy').then(function(words){
console.log(words);
});
Note: Here I am using when (a Promise+ library) instead of the Node's standard CPS style.