Is there a way to download a csv file of the data from a SQL Server database table on button click in Angular

Question

I need to get all of the data in my SQL Server database table into a .csv file when I click a button in a front end Angular web page.

I have already written a Web API in C# to access all the data from the SQL Server table and display it in my web page. I need to be able to download a .csv file when I click a button with all that data in the table displayed on my page.

export class EmployeeService {

  url = 'https://localhost:44395/Api/Employee';
  constructor(private http: HttpClient) { }

  getAllEmployee(): Observable<Employee[]> {
    return this.http.get<Employee[]>(this.url + '/AllEmployeeDetails');
  }
}

Save

Answer 1

Since you have to display the data in your angular application the best solution is to send the data as json and the use the following npm package: https://www.npmjs.com/package/xlsx to convert the json to xlsx file or csv

Here is a sample service i have written for the same, just create this service and call the function where you need it:

excel.service.ts

import { Injectable } from '@angular/core';
import * as XLSX from 'xlsx';

@Injectable({
  providedIn: 'root'
})

export class ExcelService {

  constructor() { }


  jsonToExcelSheet(data: any[], file_name = 'temp.xlsx') {

    const workBook = XLSX.utils.book_new(); // create a new blank book
    const workSheet = XLSX.utils.json_to_sheet(data);
    let wscols = [{ wpx: 150 }, { wpx: 200 }, { wpx: 150 }, { wpx: 150 }];
    workSheet['!cols'] = wscols; // set cell width
    XLSX.utils.book_append_sheet(workBook, workSheet, 'data'); // add the worksheet to the book
    return XLSX.writeFile(workBook, file_name); // initiate a file download in browser

  }


  jsonToCSV(data: any[], file_name = 'temp') {

    const workBook = XLSX.utils.book_new(); // create a new blank book
    const workSheet = XLSX.utils.json_to_sheet(data);

    XLSX.utils.book_append_sheet(workBook, workSheet, 'data'); // add the worksheet to the book
    return XLSX.writeFile(workBook, `${file_name}.csv`); // initiate a file download in browser

  }




}

Now if you want to use this service just import it in the desired component.ts

import { ExcelService } from 'src/services/excel.service';

constructor(private _excelService: ExcelService){}

async downloadWorksheet() {

   let downloadData = {} // load your data here 

   // export the json as excelsheet
   await this._excelService.jsonToExcelSheet(downloadData);
}

Answer 2

You can use the package, file-saver for downloading files from blob. Load the data and generate a CSV string which can be converted into a blob object.

npm i file-saver

npm i @types/file-saver

app.component.ts :

import { saveAs } from 'file-saver'

download(){
    // Variable to store data as CSV string 
    let csvStr = '';
    // Fetch data from service
    this.employeeService.getAllEmployee().subscribe(
        response => { 
            // Manipulate data to generate CSV string
        },error => {}
    );
   
    // Convert string to blob
    var csvBlob = new Blob([csvStr], {
      type: 'text/plain'
    });
    // Download
    saveAs(csvBlob,'data.csv')
}

Demo: https://stackblitz.com/edit/angular-zhqbgp