Open PDF file from Box cloud file storage

13 Jul 20247 minutes to read

To load a PDF file from Box cloud file storage in a PDF Viewer, you can follow the steps below

Step 1 Set up a Box developer account and create a Box application

To access Box storage programmatically, you’ll need a developer account with Box. Go to the Box Developer Console, sign in or create a new account, and then create a new Box application. This application will provide you with the necessary credentials Client ID and Client Secret to authenticate and access Box APIs. Before accessing files, you need to authenticate your application to access your Box account. Box API supports OAuth 2.0 authentication for this purpose.

Step 2: Create a Simple PDF Viewer Sample in JavaScript

Start by following the steps provided in this link to create a simple PDF viewer sample in JavaScript. This will give you a basic setup of the PDF viewer component.

Step 3: Modify the PdfViewerController.cs File in the Web Service Project

Create a web service project in .NET Core 3.0 or above. You can refer to this link for instructions on how to create a web service project.
Open the PdfViewerController.cs file in your web service project.
Import the required namespaces at the top of the file:

using Box.V2;
using Box.V2.Auth;
using Box.V2.Config;
using Box.V2.Models;

Add the following private fields and constructor parameters to the PdfViewerController class, In the constructor, assign the values from the configuration to the corresponding fields

private IConfiguration _configuration;
public readonly string _accessToken;
public readonly string _clientID;
public readonly string _clientSecret;
public readonly string _folderID;

public PdfViewerController(IWebHostEnvironment hostingEnvironment, IMemoryCache cache, IConfiguration configuration)
{
  _hostingEnvironment = hostingEnvironment;
  _cache = cache;
   _configuration = configuration;
  _accessToken = _configuration.GetValue<string>("AccessToken");
  _clientID = _configuration.GetValue<string>("ClientID");
  _clientSecret = _configuration.GetValue<string>("ClientSecret");
  _folderID = _configuration.GetValue<string>("FolderID");
}

Modify the Load() method to load the PDF file from Box cloud file storage.

[HttpPost("Load")]
[Microsoft.AspNetCore.Cors.EnableCors("MyPolicy")]
[Route("[controller]/Load")]
//Post action for Loading the PDF documents 

public async Task<IActionResult> Load([FromBody] Dictionary<string, string> jsonObject)
{
  //Initialize the PDF viewer object with memory cache object
  PdfRenderer pdfviewer = new PdfRenderer(_cache);

  MemoryStream stream = new MemoryStream();
  object jsonResult = new object();
  if (jsonObject != null && jsonObject.ContainsKey("document"))
  {
    if (bool.Parse(jsonObject["isFileName"])) 
    {
      string objectName = jsonObject["document"];

      // Initialize the Box API client with your authentication credentials
      var auth = new OAuthSession(_accessToken, "YOUR_REFRESH_TOKEN", 3600, "bearer");
      var config = new BoxConfigBuilder(_clientID, _clientSecret, new Uri("http://boxsdk")).Build();
      var client = new BoxClient(config, auth);

      // Download the file from Box storage
      var items = await client.FoldersManager.GetFolderItemsAsync(_folderID, 1000, autoPaginate: true);
      var files = items.Entries.Where(i => i.Type == "file");

      // Filter the files based on the objectName
      var matchingFile = files.FirstOrDefault(file => file.Name == objectName);

      // Fetch the file from Box storage by its name
      var fileStream = await client.FilesManager.DownloadAsync(matchingFile.Id);
      stream = new MemoryStream();
      await fileStream.CopyToAsync(stream);

      // Reset the position to the beginning of the stream
      stream.Position = 0;
    }
    else
    {
      byte[] bytes = Convert.FromBase64String(jsonObject["document"]);
      stream = new MemoryStream(bytes);
    }
  }
  jsonResult = pdfviewer.Load(stream, jsonObject);
  return Content(JsonConvert.SerializeObject(jsonResult));
}

Open the appsettings.json file in your web service project, Add the following lines below the existing "AllowedHosts" configuration

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*",
  "AccessToken": "Your_Box_Storage_Access_Token",
  "FolderID": "Your_Folder_ID",
  "ClientID": "Your_Box_Storage_ClientID",
  "ClientSecret": "Your_Box_Storage_ClientSecret"
}

NOTE

replace Your_Box_Storage_Access_Token with your actual box access token, and Your_Folder_ID with the ID of the folder in your box storage where you want to perform specific operations. Remember to use your valid box API credentials, as Your_Box_Storage_ClientID and Your_Box_Storage_ClientSecret” are placeholders for your application’s API key and secret.

Step 4: Set the PDF Viewer Properties in JavaScript PDF viewer component

Modify the serviceUrl property of the PDF viewer component with the accurate URL of your web service project, replacing https://localhost:44396/pdfviewer with the actual URL of your server. Set the documentPath property of the PDF viewer component to the desired name of the PDF file you wish to load from Box cloud file storage. Ensure that you correctly pass the document name from the files available in your box folder to the documentPath property.

import { PdfViewer, Toolbar, Magnification, Navigation, LinkAnnotation,ThumbnailView,
         BookmarkView, TextSelection, Annotation, FormFields, FormDesigner} from '@syncfusion/ej2-pdfviewer';

PdfViewer.Inject( Toolbar,Magnification,Navigation, LinkAnnotation,ThumbnailView,
                  BookmarkView, TextSelection, Annotation, FormFields, FormDesigner);

let viewer: PdfViewer = new PdfViewer();
// Replace the "localhost:44396" with the actual URL of your server
viewer.serviceUrl = 'https://localhost:44396/pdfviewer';
viewer.appendTo('#pdfViewer');
viewer.load('PDF_Succinctly.pdf', null);

NOTE

The Box.V2.Core NuGet package must be installed in your application to use the previous code example.

NOTE

Replace PDF_Succinctly.pdf with the actual document name that you want to load from Box cloud file storage. Make sure to pass the document name from the box folder to the documentPath property of the PDF viewer component

View sample in GitHub