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How to Download Multiple Files as a .Zip File using Angular

This article helps you to download multiple files as a zip file using Angular and SharePoint Online.

Prerequisites

  1. Download and Install Node from Node
  2. Install and create an Angular project using Angular CLI from here: Angular CLI 
  3. Create a document library and upload the sample files in it.

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To create the zip file in Angular, the way we were required to for the js zip library file.

npm i jszip

To save the file on the client-side, we are required to file-save the library file.

npm i file-saver

Create a component(FileDownloaderClient) in Angular for downloading the file on the client side.

 g c File/FileDownloaderClient

To show the files in the browser, PrimeNG table has been used. To know more details about PrimeNG, refer here.

Now the file-downloader-client.component.html will look like the following:

<p-table [value]="filesArray">  
    <ng-template pTemplate="header">  
        <tr>  
            <th>Sr.No</th>  
            <th>  
                File Name  
            </th>  
        </tr>  
    </ng-template>  
    <ng-template pTemplate="body" let-item let-rowIndex="rowIndex">  
        <tr>  
            <td>{{rowIndex + 1}}</td>  
            <td>  
                <a href={{item.FileRef}}>{{item.FileLeafRef}}</a>  
            </td>  
        </tr>  
    </ng-template>  
</p-table>  
<p-button label="Download" type="button" (click)="downloadFile()"></p-button>

Import the install library in file-downloader-client.component.ts

import * as JSZip from 'jszip';  
import * as FileSaver from 'file-saver';

The complete file-downloader-client.component.ts will look like:

import { Component, OnInit } from '@angular/core';  
import { HttpClient, HttpHeaders, HttpErrorResponse } from '@angular/common/http';  
import * as JSZip from 'jszip';  
import * as FileSaver from 'file-saver';  
import { TableModule } from 'primeng/table';  
import { GlobalServicesService } from 'src/app/services/global-services.service';  
@Component({  
  selector: 'app-file-downloader-client',  
  templateUrl: './file-downloader-client.component.html',  
  styleUrls: ['./file-downloader-client.component.css']  
})  
export class FileDownloaderClientComponent implements OnInit {  
  jsonHeader = 'application/json; odata=verbose';  
  headersOld = new Headers({ 'Content-Type': this.jsonHeader, Accept: this.jsonHeader });  
  headers = { 'Content-Type': this.jsonHeader, Accept: this.jsonHeader };  
  filesArray: [];  
  showFileArray: [];  
  constructor(  
    private httpClient: HttpClient,  
    private globalService: GlobalServicesService  
  ) { }  
  ngOnInit() {  
    this.getFilesFromLibrary();  
  }  
  async readFiles(listName: string, options?: any) {  
    let res;  
    const url = this.globalService.sharePointPageObject.webAbsoluteUrl + '/_api/web/lists/GetByTitle(\'' + listName + '\')/items?$select=FileRef,FileLeafRef';  
    res = await this.httpClient.get(url, this.getHeaders(true, true)).toPromise().catch((err: HttpErrorResponse) => {  
      const error = err.error;  
      return error;  
    });  
    return this.parseResults(res);  
  }  
  parseResults(res) {  
    if (res) {  
      if (res.hasOwnProperty('d') && res.d.hasOwnProperty('results')) {  
        return res.d.results;  
      } else if (res.hasOwnProperty('error')) {  
        const obj: any = res.error;  
        obj.hasError = true;  
        return obj;  
      } else {  
        return {  
          hasError: true,  
          comments: res  
        };  
      }  
    } else {  
      return {  
        hasError: true,  
        comments: 'Check the response in network trace'  
      };  
    }  
  }  
  getHeaders(bAddContext, returnOp) {  
    const headerCopy: any = Object.assign({}, this.headers);  
    if (bAddContext) {  
      const context: any = document.getElementById('__REQUESTDIGEST');  
      if (context) {  
        headerCopy['X-RequestDigest'] = context.value;  
      }  
    }  
    if (returnOp) {  
      const httpOptions = {  
        headers: new HttpHeaders(headerCopy)  
      };  
      return httpOptions;  
    } else {  
      return headerCopy;  
    }  

  }  

  async getFilesFromLibrary() {  
    const results = await this.readFiles('Test_ABC');  
    this.filesArray = results;  
    console.log(results);  
  }  
  downloadFile() {  
    this.createZip(this.filesArray.map(c => c.FileRef), 'Sample');  
  }  
  async getFile(url: string) {  
    const httpOptions = {  
      responseType: 'blob' as 'json'  
    };  
    const res = await this.httpClient.get(url, httpOptions).toPromise().catch((err: HttpErrorResponse) => {  
      const error = err.error;  
      return error;  
    });  
    return res;  
  }  
  async createZip(files: any[], zipName: string) {  
    const zip = new JSZip();  
    const name = zipName + '.zip';  
    // tslint:disable-next-line:prefer-for-of  
    for (let counter = 0; counter < files.length; counter++) {  
      const element = files[counter];  
      const fileData: any = await this.getFile(element);  
      const b: any = new Blob([fileData], { type: '' + fileData.type + '' });  
      zip.file(element.substring(element.lastIndexOf('/') + 1), b);  
    }  
    zip.generateAsync({ type: 'blob' }).then((content) => {  
      if (content) {  
        FileSaver.saveAs(content, name);  
      }  
    });  
  }  
}

Now run npm run start in terminal and browse http://localhost:4200/#/fileDownload to view the file on the browser.

Click on the download button to download the file as a zip folder.

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