# Very Simplest Way to Create CSV Out of JSON, List Data, or Almost anything \n In this Example We will Make CSV of a JSON that has List<Map<String, dynamic>> Data

JSON2CSV.dart

import 'dart:convert';
import 'dart:io';

// This Will extract data from JSON file and Create CSV file. 
// people.json DownloadLink : https://gist.githubusercontent.com/code-simple/dff6ec9eaa0816131d7273578f38c3e1/raw/6c8e8b9bb36003c2f3b9ca3cefc8a4bcfe2910eb/people.json
// new.csv DownloadLink : https://gist.githubusercontent.com/code-simple/7cae32a464f8a9995a6e510528edc576/raw/d31870b6dac5781ac4ee1d203e66334320bfec96/new.csv
void main() {
  
  // Read CSV [Simple CSV that has first row header, and data in next rows]
  List<Map<dynamic, dynamic>> readCSV(String fileName) {
//   // Reading CSV
    File r = File(fileName);
    // CSV converted to List splitted by new line
    var csvInput = (r.readAsStringSync()).split('\n');
    List<Map<dynamic, dynamic>> csvData = [];

// Prepare header Of CSV
    var header = [];
    for (var i = 0; i < csvInput[0].split(',').length - 1; i++) {
      header.add(csvInput[0].split(',')[i]);
    }
// Extract Data to its relevant Header
    for (int i = 0; i < csvInput.length - 1; i++) {
      csvData.add({}); // We add
      // If CSV File Row is Empty, i.e when reach at bottom return Null
      if (csvInput[i].isNotEmpty) {
        for (var j = 0; j < header.length; j++) {
          csvData[i][header[j]] = csvInput[i].split(',')[j];
        }
      }
    }
    return csvData;
  }
  
///-------------------- [Write to CSV] ------------------
/// Description : This Method will write Any JSON file to CSV , plus it will also accept List<dynamic>
// Either Provide JSON file Path or List<dynamic> , jsonFileName or listDynamic either one.
   writeCSV(
      {String jsonFileName = '',
      String outputCSV = 'outputCSV.csv',
      List<dynamic> listDynamic = const []}) {
    var jsonData, f;
// Check Which Method selected, Either File or List<dynamic>
    if (jsonFileName.isEmpty) {
      jsonData = listDynamic;
    } else {
      File f = File(jsonFileName);
      jsonData = jsonDecode(f.readAsStringSync());
    }
//Prepare header of columns
    var header = [];
    for (var k in jsonData[0].entries) {
      header.add(k.key);
    }
    String data = '';
    for (var i = 0; i < header.length; i++) {
      data += header[i] + ',';
    }
// Removes Comma at last of header and adding newline
    data = data.substring(0, data.length - 1) + '\n';

    for (var i = 0; i < jsonData.length; i++) {
      for (var j = 0; j < header.length; j++) {
        var increment = '${jsonData[i][header[j]]},';
        data += increment;
      }
//Removes Comma at last of row and add newline
      data = data.substring(0, data.length - 1) + '\n';
    }
//When complete then remove last empty line
    data = data.substring(0, data.length - 1);
    print(data);
    File csv = File(outputCSV);
    csv.writeAsStringSync(data);
  }
}