Open PDF from Google Drive in ASP.NET MVC

17 Nov 20258 minutes to read

Follow these steps to load a PDF from Google Drive using the server-backed PDF Viewer.

Step 1: Set up Google Drive API

You must set up a project in the Google Developers Console and enable the Google Drive API. Obtain the necessary credentials to access the API. For more information, view the official link.

Step 2: Create a PDF Viewer sample in ASP.NET MVC

Follow instructions provided in the Syncfusion^® PDF Viewer Getting Started Guide to create a simple PDF Viewer sample in ASP.NET MVC.

Step 3: Modify the HomeController.cs file in the project

1. Import the required namespaces at the top of the file.

using System.IO;
using Google.Apis.Drive.v3;
using Google.Apis.Auth.OAuth2;
using Google.Apis.Services;
using Google.Apis.Util.Store;

1. Modify the Load() method to load the PDF files from Google drive.

// Specify the path to the credentials file
private string credentialsPath = "Your Path to the OAuth 2.0 Client IDs json file";
// Specify the folder ID where you want to upload the PDF on Google Drive
private readonly string folderId = "Your Google Drive Folder ID";
private readonly string ApplicationName = "Your Application Name";
private readonly string tokenjson = "Path to create token.json file";

 public async Task<ActionResult> Load(jsonObjects jsonObject)
 {
     PdfRenderer pdfviewer = new PdfRenderer();
     MemoryStream stream = new MemoryStream();
     var jsonData = JsonConverter(jsonObject);
     object jsonResult = new object();

     if (jsonObject != null && jsonData.ContainsKey("document"))
     {
         if (bool.Parse(jsonData["isFileName"]))
         {
             string objectName = jsonData["document"];

             // Google Drive API setup
             UserCredential credential;
             string[] Scopes = { DriveService.Scope.DriveReadonly };

             // Load the credentials file
             using (var streammen = new FileStream(credentialsPath, FileMode.Open, FileAccess.Read))
             {
                 // The file token.json stores the user's access and refresh tokens, and is created
                 // automatically when the authorization flow completes for the first time.
                 string tokenPath = tokenjson;
                 credential = GoogleWebAuthorizationBroker.AuthorizeAsync(
                     GoogleClientSecrets.Load(streammen).Secrets,
                     Scopes,
                     "user",
                     CancellationToken.None,
                     new FileDataStore(tokenPath, true)).Result;
             }

             // Create the Drive service
             var service = new DriveService(new BaseClientService.Initializer()
             {
                 HttpClientInitializer = credential,
                 ApplicationName = ApplicationName,
             });


             FilesResource.ListRequest listRequest = service.Files.List();
             listRequest.Q = "mimeType='application/pdf' and '" + folderId + "' in parents and trashed=false";
             listRequest.Fields = "files(id, name)";
             var files = await listRequest.ExecuteAsync();

             // Process the list of files (you can use 'files' to retrieve the list of files)
             string fileIdToDownload = null;
             foreach (var file in files.Files)
             {
                 string fileId = file.Id;
                 string fileName = file.Name;
                 if (fileName == objectName)
                 {
                     // Save the matching fileId
                     fileIdToDownload = fileId;
                     break;
                 }
             }
             string fileIds = fileIdToDownload;
             var request = service.Files.Get(fileIds);
             await request.DownloadAsync(stream);
             stream.Position = 0;
         }
         else
         {
             byte[] bytes = Convert.FromBase64String(jsonData["document"]);
             stream = new MemoryStream(bytes);
         }
     }

     jsonResult = pdfviewer.Load(stream, jsonData);
     return Content(JsonConvert.SerializeObject(jsonResult));
 }

NOTE

Replace Your Google Drive Folder ID, Your Application name, and Your Path to the OAuth 2.0 Client IDs json file with your actual Google drive folder ID , Your name for your application and the path for the JSON file.

NOTE

The FolderId part is the unique identifier for the folder. For example, if your folder URL is: https://drive.google.com/drive/folders/abc123xyz456, then the folder ID is abc123xyz456.

Step 4: Configure the PDF Viewer component

Set the serviceUrl to your web service endpoint (replace the localhost URL with your server URL). Set documentPath to the PDF file name to load from Google Drive. Ensure the document name exists in your Drive folder.

@{
    ViewBag.Title = "Home Page";
}

<div>
    <div style="height:500px;width:100%;">
        @Html.EJS().PdfViewer("pdfviewer").ServiceUrl(VirtualPathUtility.ToAbsolute("~/Home/")).DocumentPath("PDF_Succinctly.pdf").Render()
    </div>
</div>

NOTE

The Google.Apis.Drive.v3 NuGet package must be installed in your application to use the previous code example.

View sample in GitHub