Convert an external JSON to a CSV in Node JS

Question

I am creating a project in Node JS and Typescript in which I want to download a CSV with the information that an API contains in JSON format. Given the url http://localhost:3000/?api=api1, I have to read the JSON related to api1.

I have added the modules that I have seen that are necessary but I cannot download the CSV from an external JSON by url.

This is my controller:

import { Request, Response } from 'express';
const converter = require("json-2-csv");
const fetch = require("node-fetch");
const fs = require("fs");
const flatten = require('flat');
    
const conf = require(`../config/${process.env.NODE_ENV}.json`);
    
class IndexController {
    public async index(req: Request, res: Response) {
        const api =req.query.api; //api1
        const url = conf.API_MOCS[`${api}`].url; //https://mocks.free.beeceptor.com/api1 

        const env = process.env.NODE_ENV;
        const nameFile = `${env}.${api}.csv`;

        let json = await axios.get(url);

        const header={
          'index':'Index',
          'integer':'Integer',
          'float': 'Float',
          'name': 'Name'};

        let json2csvCallback = function (err:any, csv:any) {
           if (err) throw err;
           const maxRecords = 50;
           const headers = csv.split('\n').slice(0,1);
           const records = csv.split('\n').slice(0,);
           for(let i=1; i<records.length; i=i+maxRecords) {
                let dataOut = headers.concat(records.slice(i, i+maxRecords)).join('\n');
                let id = Math.floor(i/maxRecords)+1;
                 fs.writeFileSync(`${dir}/${nameFile}.${id}.csv`, dataOut);
            }
        };

        converter.json2csv(json.data.items, json2csvCallback);
    }
}
export const indexController = new IndexController(); 

In a file I have stored the URL where the information is in JSON, which I read with the variable (url), how can I download the information from that URL in a CSV file with a maximum of 999 lines and save it in src / output?

Answer 1

You can call that url using axios or request, after getting the JSON in response you can use https://www.npmjs.com/package/json2csv to convert JSON to csv.

import { Request, Response } from 'express';
const converter = require("json-2-csv");
const fetch = require("node-fetch");
const axios = require('axios');
const fs = require("fs");
const flatten = require('flat');
    
const conf = require(`../config/${process.env.NODE_ENV}.json`);
    
class IndexController {
    public async index(req: Request, res: Response) {
        const api =req.query.api; //api1
        const url = conf.API_MOCS[`${api}`].url; //https://mocks.free.beeceptor.com/api1 
        console.log("Getting JSON ...");
        let json = await axios.get("https://mocks.free.beeceptor.com/api1");
        console.log("JSON Fetched ...");
        const header={
        'index':'Index',
        'index_start_at':'Index start',
         'integer':'Integer',
        'float': 'Float',
        'name': 'Name'};
        converter.json2csv([header,...json.data.items], (err:any, csv:any) => {
            if (err) {
                 throw err;
            }
            console.log("Making CSV ...");
            fs.writeFileSync("file.csv",csv);
            console.log("CSV File Is Ready...");

         });    
    }
}
export const indexController = new IndexController();