How to create PDF Viewer web service application in ASP.NET Core?
The Essential ASP.NET Core PDF Viewer has server-side dependency to get the details from PDF documents for rendering. This section explains how to create the service for PDF Viewer to perform server-side preprocessing of the PDF document to be rendered in client-side.
Prerequisites
To get started with ASP.NET Core Web API service, ensure that the following software is installed on the machine:
- Visual Studio 2017
- DotNet Core 2.0
ASP.NET Core application setup with Web API for PDF Viewer service
The following steps are used to create PDF Viewer service:
- Select File > New > Project in the Visual Studio menu bar.
- Select Installed > Visual C# > .NET Core and choose the required .NET Framework in the drop-down.
- Select ASP.NET Core Web Application and change the application name, and then click OK.
- Select API, and then click OK. The web application project is now created with default ASP.NET Core template.
- After creating the project, add the Syncfusion.EJ2.PdfViewer.AspNet.Core.Windows dependency to your project by using ‘NuGet Package Manager’.
Open the NuGet package manager.
Install the Syncfusion.EJ2.PdfViewer.AspNet.Core.Windows package to the application.
For Linux and OSX operating systems, use the following corresponding libraries:
- Syncfusion.EJ2.PdfViewer.AspNet.Core.Linux
- Syncfusion.EJ2.PdfViewer.AspNet.Core.OSX
- Rename the ValuesController.cs to PdfViewerController.cs inside the Controllers folder and add the following code.
C#
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Newtonsoft.Json;
using Syncfusion.EJ2.PdfViewer;
using System;
using System.Collections.Generic;
using System.IO;
namespace ej2_pdfviewer_service.Controllers
{
public class PdfViewerController : Controller
{
private IHostingEnvironment _hostingEnvironment;
//Initialize the memory cache object
public IMemoryCache _cache;
public PdfViewerController(IHostingEnvironment hostingEnvironment, IMemoryCache cache)
{
_hostingEnvironment = hostingEnvironment;
_cache = cache;
}
[AcceptVerbs("Post")]
[HttpPost]
[Microsoft.AspNetCore.Cors.EnableCors("MyPolicy")]
//Post action for Loading the PDF documents
public 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 documentPath = GetDocumentPath(jsonObject["document"]);
if (!string.IsNullOrEmpty(documentPath))
{
byte[] bytes = System.IO.File.ReadAllBytes(documentPath);
stream = new MemoryStream(bytes);
}
else
{
return this.Content(jsonObject["document"] + " is not found");
}
}
else
{
byte[] bytes = Convert.FromBase64String(jsonObject["document"]);
stream = new MemoryStream(bytes);
}
}
jsonResult = pdfviewer.Load(stream, jsonObject);
return Content(JsonConvert.SerializeObject(jsonResult));
}
[AcceptVerbs("Post")]
[HttpPost]
[Microsoft.AspNetCore.Cors.EnableCors("MyPolicy")]
//Post action for processing the bookmarks from the PDF documents
public IActionResult Bookmarks([FromBody] Dictionary<string, string> jsonObject)
{
//Initialize the PDF Viewer object with memory cache object
PdfRenderer pdfviewer = new PdfRenderer(_cache);
var jsonResult = pdfviewer.GetBookmarks(jsonObject);
return Content(JsonConvert.SerializeObject(jsonResult));
}
[AcceptVerbs("Post")]
[HttpPost]
[Microsoft.AspNetCore.Cors.EnableCors("MyPolicy")]
//Post action for processing the PDF documents
public IActionResult RenderPdfPages([FromBody] Dictionary<string, string> jsonObject)
{
//Initialize the PDF Viewer object with memory cache object
PdfRenderer pdfviewer = new PdfRenderer(_cache);
object jsonResult = pdfviewer.GetPage(jsonObject);
return Content(JsonConvert.SerializeObject(jsonResult));
}
[AcceptVerbs("Post")]
[HttpPost]
[Microsoft.AspNetCore.Cors.EnableCors("MyPolicy")]
//Post action for rendering the ThumbnailImages
public IActionResult RenderThumbnailImages([FromBody] Dictionary<string, string> jsonObject)
{
//Initialize the PDF Viewer object with memory cache object
PdfRenderer pdfviewer = new PdfRenderer(_cache);
object result = pdfviewer.GetThumbnailImages(jsonObject);
return Content(JsonConvert.SerializeObject(result));
}
[AcceptVerbs("Post")]
[HttpPost]
[Microsoft.AspNetCore.Cors.EnableCors("MyPolicy")]
//Post action for rendering the annotations
public IActionResult RenderAnnotationComments([FromBody] Dictionary<string, string> jsonObject)
{
//Initialize the PDF Viewer object with memory cache object
PdfRenderer pdfviewer = new PdfRenderer(_cache);
object jsonResult = pdfviewer.GetAnnotationComments(jsonObject);
return Content(JsonConvert.SerializeObject(jsonResult));
}
[AcceptVerbs("Post")]
[HttpPost]
[Microsoft.AspNetCore.Cors.EnableCors("MyPolicy")]
//Post action to export annotations
public IActionResult ExportAnnotations([FromBody] Dictionary<string, string> jsonObject)
{
PdfRenderer pdfviewer = new PdfRenderer(_cache);
string jsonResult = pdfviewer.GetAnnotations(jsonObject);
return Content(jsonResult);
}
[AcceptVerbs("Post")]
[HttpPost]
[Microsoft.AspNetCore.Cors.EnableCors("MyPolicy")]
//Post action to import annotations
public IActionResult ImportAnnotations([FromBody] Dictionary<string, string> jsonObject)
{
PdfRenderer pdfviewer = new PdfRenderer(_cache);
string jsonResult = string.Empty;
if (jsonObject != null && jsonObject.ContainsKey("fileName"))
{
string documentPath = GetDocumentPath(jsonObject["fileName"]);
if (!string.IsNullOrEmpty(documentPath))
{
jsonResult = System.IO.File.ReadAllText(documentPath);
}
else
{
return this.Content(jsonObject["document"] + " is not found");
}
}
return Content(jsonResult);
}
[AcceptVerbs("Post")]
[HttpPost]
[Microsoft.AspNetCore.Cors.EnableCors("MyPolicy")]
//Post action for unloading and disposing the PDF document resources
public IActionResult Unload([FromBody] Dictionary<string, string> jsonObject)
{
//Initialize the PDF Viewer object with memory cache object
PdfRenderer pdfviewer = new PdfRenderer(_cache);
pdfviewer.ClearCache(jsonObject);
return this.Content("Document cache is cleared");
}
[HttpPost]
[Microsoft.AspNetCore.Cors.EnableCors("MyPolicy")]
//Post action for downloading the PDF documents
public IActionResult Download([FromBody] Dictionary<string, string> jsonObject)
{
//Initialize the PDF Viewer object with memory cache object
PdfRenderer pdfviewer = new PdfRenderer(_cache);
string documentBase = pdfviewer.GetDocumentAsBase64(jsonObject);
return Content(documentBase);
}
[HttpPost]
[Microsoft.AspNetCore.Cors.EnableCors("MyPolicy")]
//Post action for printing the PDF documents
public IActionResult PrintImages([FromBody] Dictionary<string, string> jsonObject)
{
//Initialize the PDF Viewer object with memory cache object
PdfRenderer pdfviewer = new PdfRenderer(_cache);
object pageImage = pdfviewer.GetPrintImage(jsonObject);
return Content(JsonConvert.SerializeObject(pageImage));
}
//Gets the path of the PDF document
private string GetDocumentPath(string document)
{
string documentPath = string.Empty;
if (!System.IO.File.Exists(document))
{
var path = _hostingEnvironment.ContentRootPath;
if (System.IO.File.Exists(path + "\\Data\\" + document))
documentPath = path + "\\Data\\" + document;
}
else
{
documentPath = document;
}
return documentPath;
}
}
Change the launchUrl to pdfviewer (name of the controller) in the lauchSettings.json as follows.
{
"iisSettings": {
"windowsAuthentication": false,
"anonymousAuthentication": true,
"iisExpress": {
"applicationUrl": "http://localhost:58767/",
"sslPort": 0
}
},
"profiles": {
"IIS Express": {
"commandName": "IISExpress",
"launchBrowser": true,
"launchUrl": "pdfviewer",
"environmentVariables": {
"ASPNETCORE_ENVIRONMENT": "Development"
}
},
"ej2_pdfviewer_service": {
"commandName": "Project",
"launchBrowser": true,
"launchUrl": "pdfviewer",
"environmentVariables": {
"ASPNETCORE_ENVIRONMENT": "Development"
},
"applicationUrl": "http://localhost:62978/"
}
}
}
Configuring CORS policy
Browser security prevents a webpage from making requests to a different domain than the one that served the webpage. This restriction is called the same-origin policy. Cross Origin Resource Sharing (CORS) allows a server to relax the same-origin policy. Using CORS, a server can explicitly allow some cross-origin.
Configure a CORS policy at application Startup.cs in the ConfigureServices method using the following code.
Code snippet
public void ConfigureServices(IServiceCollection services)
{
services.AddMemoryCache();
services.AddMvc();
services.AddCors(o => o.AddPolicy("MyPolicy", builder =>
{
builder.AllowAnyOrigin()
.AllowAnyMethod()
.AllowAnyHeader();
}));
services.Configure<GzipCompressionProviderOptions>(options => options.Level = System.IO.Compression.CompressionLevel.Optimal);
services.AddResponseCompression();
}
The CorsPolicyBuilder in builder allows you to configure the policy as required. You can now use this policy name to apply the policy to controllers and action.
[Microsoft.AspNetCore.Cors.EnableCors("MyPolicy")]
Sample link: https://www.syncfusion.com/downloads/support/directtrac/general/ze/ej2-pdfviewer-web-service-1568002846
- From the 2019 Volume 2 release, new annotation features included in the PDF Viewer. So update the Scripts, CSS, and Nuget packages to the latest Essential Studio Version to work with PDF Viewer.
- From the version 17.2.0.39, we have improved the memory cache method in ASP.NET Core. So update the controller code with the above updated code snippet to work with PDF Viewer.
- You can refer to the CDN links with the required version, find the following CDN links with specific Version:
https://cdn.syncfusion.com/ej2/17.2.28/dist/ej2.min.js
https://cdn.syncfusion.com/ej2/17.2.28/material.css
Conclusion
I hope you enjoyed learning about how to create PDF Viewer web service application in ASP.NET Core.
You can refer to our ASP.NET Core PDF Viewer feature tour page to know about its other groundbreaking feature representations. You can also explore our ASP.NET Core PDF Viewer examples to understand how to present and manipulate data.
For current customers, you can check out our ASP.NET Core Controls from the License and Downloads page. If you are new to Syncfusion, you can try our 30-day free trial to check out our ASP.NET Core PDF Viewer and other ASP.NET Core controls.
If you have any queries or require clarifications, please let us know in comments below. You can also contact us through our support forums, Direct-Trac, or feedback portal. We are always happy to assist you!
See Also
