Open PDF file from Dropbox cloud file storage

5 Aug 20249 minutes to read

PDF Viewer allows to load PDF file from Drop Box using either the Standalone or Server-backed PDF Viewer. Below are the steps and a sample to demonstrate how to open a PDF from Drop Box.

Using Standalone PDF Viewer

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

Step 1 Create a Dropbox API

To create a Dropbox API App, you should follow the official documentation provided by Dropbox link. The process involves visiting the Dropbox Developer website and using their App Console to set up your API app. This app will allow you to interact with Dropbox programmatically, enabling secure access to files and data.

Step 2: Create a Simple PDF Viewer Sample in React

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

Step 3: Modify the src/index.js File in the Angular Project

Import the required namespaces at the top of the file:

import { Dropbox } from 'dropbox';

Create an instance of the Dropbox class using an access token for authentication. Next, call the filesDownload method of this Dropbox instance to download the file located at /PDF_Succinctly.pdf. Upon successfully downloading the file, extract the file blob from the response. Convert this file blob to a Base64 string using the blobToBase64 method. Finally, load the Base64 string into a PDF viewer control.

NOTE

Replace Your Access Token with the actual Access Token of your Drop Box account.

function loadDocument() {
  const dbx = new Dropbox({ accessToken: 'Your Access Token' });
  dbx.filesDownload({ path: '/PDF_Succinctly.pdf' }).then(async (response) => {
    const blob = await response.result.fileBlob;
    const base64String = await blobToBase64(blob);
    setTimeout(() => {
      viewer.load(base64String, "");
    }, 2000);
  });
}

function blobToBase64(blob){
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.onloadend = () => resolve(reader.result);
    reader.onerror = reject;
    reader.readAsDataURL(blob);
  });
}

NOTE

The npm install dropbox package must be installed in your application to use the previous code example.

View sample in GitHub

Using Server-Backed PDF Viewer

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

Step 1 Create a Dropbox API

Step 2: Create a Simple PDF Viewer Sample in React

Start by following the steps provided in this link to create a simple PDF viewer sample in React. 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 System.IO;
using Dropbox.Api;
using Dropbox.Api.Files;

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 _folderName;

public PdfViewerController(IWebHostEnvironment hostingEnvironment, IMemoryCache cache, IConfiguration configuration)
{
  _hostingEnvironment = hostingEnvironment;
  _cache = cache;
   _configuration = configuration;
  _accessToken = _configuration.GetValue<string>("AccessToken");
  _folderName = _configuration.GetValue<string>("FolderName");
}

Modify the Load() method to load the PDF from Dropbox 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"]))
    {
      // Get the file name from the jsonObject, which should contain the Dropbox file name
      string fileName = jsonObject["document"];

      using (var dropBox = new DropboxClient(_accessToken))
     {
        using (var response = await dropBox.Files.DownloadAsync(_folderName + "/" + fileName))
        {
          var byteArray = await response.GetContentAsByteArrayAsync();

          // Load the PDF file into the PDF viewer
          stream = new MemoryStream(byteArray);
        }
      }
    }
    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_Dropbox_Access_Token",
  "FolderName": "Your_Folder_Name"
}

NOTE

Replace Your_Dropbox_Access_Token with your actual Dropbox access token and Your_Folder_Name with your folder name.

Step 4: Set the PDF Viewer Properties in React 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 Dropbox cloud file storage. Ensure that you correctly pass the document name from the files available in your dropbox folder to the documentPath property.

import * as ReactDOM from 'react-dom';
import * as React from 'react';
import { PdfViewerComponent, Toolbar, Magnification, Navigation, LinkAnnotation, BookmarkView, ThumbnailView,
         Print, TextSelection, Annotation, TextSearch, Inject, FormDesigner, FormFields} from '@syncfusion/ej2-react-pdfviewer';

function App() {
  return (<div>
    <div className='control-section'>
      {/* Render the PDF Viewer */}
        <PdfViewerComponent
          id="container"
          documentPath="PDF_Succinctly.pdf"
          // Replace the "localhost:44396" with the actual URL of your server
          serviceUrl="https://localhost:44396/pdfviewer" 
          style={{ 'height': '640px' }}>
          
              <Inject services={[ Toolbar, Magnification, Navigation, Annotation, LinkAnnotation, BookmarkView, ThumbnailView,
                                  Print, TextSelection, TextSearch, FormDesigner, FormFields ]} />

        </PdfViewerComponent>
    </div>
  </div>);
}
const root = ReactDOM.createRoot(document.getElementById('sample'));
root.render(<App />);

NOTE

The Dropbox.Api NuGet package must be installed in your application to use the previous code example.

View sample in GitHub