Parsing log file to JSON object - node.js

Question

Does anyone know what the best way would be to parse a log file (Salesforce) into a structured JSON object
There are certain sections in the log file that can be identified, like EXECUTION_STARTED,EXECUTION_FINISHED, CODE_UNIT_STARTED CODE_UNIT_FINISHED and many more
There are also time information that I would like to have in the JSON object
Are there any libraries available in nodejs that could be used to accomplish this ?
I was looking into antlr4 but it seems quite complex
-Jani

Answer 1

Looks like a CSV -> JSON conversion
// Reading the file using default
// fs npm package
const fs = require("fs");
csv = fs.readFileSync("CSV_file.csv")
// Convert the data to String and
// split it in an array
var array = csv.toString().split("\r");
// All the rows of the CSV will be
// converted to JSON objects which
// will be added to result in an array
let result = [];
// The array[0] contains all the
// header columns so we store them
// in headers array
let headers = array[0].split(", ")
// Since headers are separated, we
// need to traverse remaining n-1 rows.
for (let i = 1; i < array.length - 1; i++) {
let obj = {}
// Create an empty object to later add
// values of the current row to it
// Declare string str as current array
// value to change the delimiter and
// store the generated string in a new
// string s
let str = array[i]
let s = ''
// By Default, we get the comma separated
// values of a cell in quotes " " so we
// use flag to keep track of quotes and
// split the string accordingly
// If we encounter opening quote (")
// then we keep commas as it is otherwise
// we replace them with pipe |
// We keep adding the characters we
// traverse to a String s
let flag = 0
for (let ch of str) {
if (ch === '"' && flag === 0) {
flag = 1
}
else if (ch === '"' && flag == 1) flag = 0
if (ch === ', ' && flag === 0) ch = '|'
if (ch !== '"') s += ch
}
// Split the string using pipe delimiter |
// and store the values in a properties array
let properties = s.split("|")
// For each header, if the value contains
// multiple comma separated data, then we
// store it in the form of array otherwise
// directly the value is stored
for (let j in headers) {
if (properties[j].includes(", ")) {
obj[headers[j]] = properties[j]
.split(", ").map(item => item.trim())
}
else obj[headers[j]] = properties[j]
}
// Add the generated object to our
// result array
result.push(obj)
}
// Convert the resultant array to json and
// generate the JSON output file.
let json = JSON.stringify(result);
fs.writeFileSync('output.json', json);
Change "CSV_file.csv" above to whatever your CSV file is.
Save the js file as app.js and run using
node app.js
Source: https://www.geeksforgeeks.org/how-to-convert-csv-to-json-file-having-comma-separated-values-in-node-js/