CSV to JSON in Typescript

Question

I am trying to create a JSON file from the data received from a CSV file uploaded using a file uploader input.

I have found lots of posts doing this in Javascript but they just aren't quite working for me in Typescript.

The error I get when running the below code is csv.Split is not a function, does anyone have any ideas how I can alter my code to work.

Let me know if you need more information and Thanks in advance.

component.ts

public testFile() {
    var file = (<HTMLInputElement>document.getElementById('fileInput')).files[0];        

    var jsonFile = this.csvJSON(file);


    // Set Http POST options
    let headers = new Headers({ 'Content-Type': 'application/json' });
    let options = new RequestOptions({ headers: headers });

    // Call Api with test connection data 
    this.http
        .post('/api/TestConnection/TestConnection', jsonFile, options)
        .subscribe(data => {
            // alert request ok
            alert('ok');
        }, error => {
            // Log error
            console.log(error.json());
        });
}

public csvJSON(csv) {
    var lines = csv.split("\n");

    var result = [];

    var headers = lines[0].split(",");

    for (var i = 1; i < lines.length; i++) {

        var obj = {};
        var currentline = lines[i].split(",");

        for (var j = 0; j < headers.length; j++) {
            obj[headers[j]] = currentline[j];
        }

        result.push(obj);

    }

    //return result; //JavaScript object
    return JSON.stringify(result); //JSON
}

Answer 1

import * as XLSX from 'xlsx'


uploadCSVFile(event) {
  const target: DataTransfer = <DataTransfer>(event.target);
  if (target.files.length !== 1) {
    throw new Error('Cannot use multiple files');
    }

    const filereader: FileReader = new FileReader();
    const selectedfile =  event.target.files[0];
    filereader.readAsBinaryString(selectedfile);
    filereader.onload = (event:any)=>{
      let binarydata =  event.target.result;
      let workbook  = XLSX.read (binarydata,{type:'binary'})
      workbook.SheetNames.forEach(sheet=>{
        const data = XLSX.utils.sheet_to_json(workbook.Sheets[sheet]);
        console.log(data);
      })
      
    }


}

do npm install xlsx;

in html

<input type="file" class="upload" (change)="uploadCSVFile($event)">

Answer 2

Here is my work on CSV to JSON worked perfectly.

Stackbliz Demo

contact-imports.component.ts

import { Component, OnInit, ChangeDetectorRef } from '@angular/core';
import { ToastrService } from 'ngx-toastr';

@Component({
  selector: 'app-contact-imports',
  templateUrl: './contact-imports.component.html',
  styleUrls: ['./contact-imports.component.scss']
})


export class ContactImportsComponent implements OnInit {

  csvContent: string;
  contacts: Array<any> = [];
  properties:any = "";
  flag:boolean = false;
  constructor( private toastr: ToastrService) { }
  ngOnInit() {
    
  }

  
  onFileLoad(fileLoadedEvent) {
    const textFromFileLoaded = fileLoadedEvent.target.result;
    this.csvContent = textFromFileLoaded;

    //Flag is for extracting first line
    let flag = false;
    // Main Data
    let objarray: Array<any> = [];
    //Properties
    let prop: Array<any> = [];
    //Total Length
    let size: any = 0;

    for (const line of this.csvContent.split(/[\r\n]+/)) {

      if (flag) {

        let obj = {};
        for (let k = 0; k < size; k++) {
          //Dynamic Object Properties
          obj[prop[k]] = line.split(',')[k]
        }
        objarray.push(obj);

      } else {
        //First Line of CSV will be having Properties
        for (let k = 0; k < line.split(',').length; k++) {
          size = line.split(',').length;
          //Removing all the spaces to make them usefull, also removing any " characters 
          prop.push(line.split(',')[k].replace(/ /g, '').replace(/"/g, ""));
        }
        flag = true;
      }
    }
    this.contacts = objarray;
    this.properties = [];
  
    this.properties = prop;
    console.log(this.properties);
    console.log(this.contacts);
    this.flag = true;
  

    // console.log(this.csvContent);
  }




  onFileSelect(input: HTMLInputElement) {

    const files = input.files;
    var fileTypes = ['csv'];  //acceptable file types

    if (files && files.length) {
      var extension = input.files[0].name.split('.').pop().toLowerCase(),  //file extension from input file
      isSuccess = fileTypes.indexOf(extension) > -1;  //is extension in acceptable types
       //console.log(isSuccess);
      //  console.log("Filename: " + files[0].name);
      // console.log("Type: " + files[0].type);
      //  console.log("Size: " + files[0].size + " bytes");
      if(isSuccess){
        const fileToRead = files[0];

        const fileReader = new FileReader();
        fileReader.onload = this.onFileLoad;
  
  
        fileReader.readAsText(fileToRead, "UTF-8");
      }else{
        this.toastr.error("Invalid File Type", 'Failed');
      }

    
    }

  }
}

contact-imports.component.html

 <div class="container-fluid">
      <div class="col-md-6">
          <img src="https://img.icons8.com/color/48/000000/csv.png"/> 
          <span class="text-muted" style="font-size: 22px;">Import Contacts From CSV</span>
        
     
          <div class="form-group">
                 <input class="form-control" accept=".csv" id="csv" type="file" (change)="onFileSelect($event.target)" name="myfile">
            </div>
      </div> 
    

  </div>

Answer 3

HTML

<input type="file" accept=".csv (change)="csv2Array($event)">

Typescript

csv2Array(fileInput: any){
//read file from input
this.fileReaded = fileInput.target.files[0];

let reader: FileReader = new FileReader();
reader.readAsText(this.fileReaded);

 reader.onload = (e) => {
 let csv: string = reader.result;
 let allTextLines = csv.split(/\r|\n|\r/);
 let headers = allTextLines[0].split(',');
 let lines = [];

  for (let i = 0; i < allTextLines.length; i++) {
    // split content based on comma
    let data = allTextLines[i].split(',');
    if (data.length === headers.length) {
      let tarr = [];
      for (let j = 0; j < headers.length; j++) {
        tarr.push(data[j]);
      }

     // log each row to see output 
     console.log(tarr);
     lines.push(tarr);
  }
 }
 // all rows in the csv file 
 console.log(">>>>>>>>>>>>>>>>>", lines);
} 
}

Answer 4

You are passing File to csvJSON method instead of file's text. You can use FileReader to read its content. Here's an example

const convertFile = () => {
  const input = document.getElementById('fileInput');

  const reader = new FileReader();
  reader.onload = () => {
    let text = reader.result;
    console.log('CSV: ', text.substring(0, 100) + '...');
    
    //convert text to json here
    //var json = this.csvJSON(text);
  };
  reader.readAsText(input.files[0]);
};

<input type='file' onchange='convertFile(event)' id='fileInput'>