How to Upload and Download PDF Files in ASP .NET C# with IronPDF

How Do You Create a Database Table for PDF Storage?

The first step involves creating a database table to store uploaded PDF files as binary data. The following code shows a model class representing the file structure with properties for the file name, content type, and byte array storage. This is a common pattern in New Tutorials involving file persistence in EF Core.

public class PdfFileModel
{
    public int Id { get; set; }
    public string FileName { get; set; }
    public string ContentType { get; set; }
    public byte[] FileData { get; set; }
    public DateTime UploadedDate { get; set; }
}

public class PdfFileModel
{
    public int Id { get; set; }
    public string FileName { get; set; }
    public string ContentType { get; set; }
    public byte[] FileData { get; set; }
    public DateTime UploadedDate { get; set; }
}

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This model maps directly to a database table where FileData stores the PDF document as a varbinary column. The FileName property preserves the original file name, while ContentType ensures proper content disposition when serving the download PDF file to users. You may also add Details columns or metadata fields depending on your requirements.

How Can You Upload PDF Files to a Database in ASP.NET Core?

To upload one or more files, create a controller action that accepts an IFormFile parameter. The FileUpload Control in your HTML form must use enctype="multipart/form-data" to properly Load the uploaded file to the server and ensure the PDF bytes are transmitted correctly. Note that your namespace will be the same as your project name.

namespace UploadPdfs.Controllers
{
public class PdfController : Controller
{
    private readonly ApplicationDbContext _context;
    public PdfController(ApplicationDbContext context)
    {
        _context = context;
    }
    [HttpPost]
    public async Task<IActionResult> Upload(IFormFile file)
    {
        if (file == null || file.Length == 0)
            return BadRequest("No file selected");
        using (var stream = new MemoryStream())
        {
            await file.CopyToAsync(stream);
            var pdfFile = new PdfFileModel
            {
                FileName = file.FileName,
                ContentType = file.ContentType,
                FileData = stream.ToArray(),
                UploadedDate = DateTime.Now
            };
            _context.PdfFiles.Add(pdfFile);
            await _context.SaveChangesAsync();
        }
        return RedirectToAction("Index");
    }
}
}

namespace UploadPdfs.Controllers
{
public class PdfController : Controller
{
    private readonly ApplicationDbContext _context;
    public PdfController(ApplicationDbContext context)
    {
        _context = context;
    }
    [HttpPost]
    public async Task<IActionResult> Upload(IFormFile file)
    {
        if (file == null || file.Length == 0)
            return BadRequest("No file selected");
        using (var stream = new MemoryStream())
        {
            await file.CopyToAsync(stream);
            var pdfFile = new PdfFileModel
            {
                FileName = file.FileName,
                ContentType = file.ContentType,
                FileData = stream.ToArray(),
                UploadedDate = DateTime.Now
            };
            _context.PdfFiles.Add(pdfFile);
            await _context.SaveChangesAsync();
        }
        return RedirectToAction("Index");
    }
}
}

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<form method="post" action="/Pdf/Upload" enctype="multipart/form-data">
    <button type="submit">Upload</button>
</form>

<form method="post" action="/Pdf/Upload" enctype="multipart/form-data">
    <button type="submit">Upload</button>
</form>

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How Do You Process Uploaded PDF Files with Watermarks?

Before saving uploaded PDF files to the database, you can process them using IronPDF's watermarking features. This allows adding branding, "DRAFT" labels, or "CONFIDENTIAL" stamps to every PDF document that enters your system.

[HttpPost]
 public async Task<IActionResult> UploadWithWatermark(IFormFile file)
 {
     if (file == null || file.Length == 0)
         return BadRequest("No file selected");
     // 1. Read the uploaded file into a byte array
     using (var stream = new MemoryStream())
     {
         await file.CopyToAsync(stream);
         byte[] fileBytes = stream.ToArray();
         // 2. Process with IronPDF (Apply Watermark)
         var PDF = new IronPdf.PdfDocument(fileBytes);
         pdf.ApplyWatermark("<h2 style='color:red'>CONFIDENTIAL</h2>", 60, IronPdf.Editing.VerticalAlignment.Middle, IronPdf.Editing.HorizontalAlignment.Center);
         // 3. Define the new file name and path
         string uniqueFileName = Guid.NewGuid().ToString() + "_" + file.FileName;
         string filePath = Path.Combine(_storagePath, uniqueFileName);
         // 4. Save the processed bytes to the file system
         System.IO.File.WriteAllBytes(filePath, pdf.BinaryData);
         // 5. Save metadata to the in-memory list (instead of DB)
         var pdfFile = new PdfFileModel
         {
             Id = _nextId++,
             FileName = file.FileName,
             ContentType = "application/pdf",
             FilePath = filePath, // Store the physical path
             UploadedDate = DateTime.Now
         };
         _pdfFiles.Add(pdfFile);
     }
     return RedirectToAction("Index");
 }

[HttpPost]
 public async Task<IActionResult> UploadWithWatermark(IFormFile file)
 {
     if (file == null || file.Length == 0)
         return BadRequest("No file selected");
     // 1. Read the uploaded file into a byte array
     using (var stream = new MemoryStream())
     {
         await file.CopyToAsync(stream);
         byte[] fileBytes = stream.ToArray();
         // 2. Process with IronPDF (Apply Watermark)
         var PDF = new IronPdf.PdfDocument(fileBytes);
         pdf.ApplyWatermark("<h2 style='color:red'>CONFIDENTIAL</h2>", 60, IronPdf.Editing.VerticalAlignment.Middle, IronPdf.Editing.HorizontalAlignment.Center);
         // 3. Define the new file name and path
         string uniqueFileName = Guid.NewGuid().ToString() + "_" + file.FileName;
         string filePath = Path.Combine(_storagePath, uniqueFileName);
         // 4. Save the processed bytes to the file system
         System.IO.File.WriteAllBytes(filePath, pdf.BinaryData);
         // 5. Save metadata to the in-memory list (instead of DB)
         var pdfFile = new PdfFileModel
         {
             Id = _nextId++,
             FileName = file.FileName,
             ContentType = "application/pdf",
             FilePath = filePath, // Store the physical path
             UploadedDate = DateTime.Now
         };
         _pdfFiles.Add(pdfFile);
     }
     return RedirectToAction("Index");
 }

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How Can You Download Files from the Database?

To download PDF files stored in your database, create an action that retrieves the byte array and returns it as a FileResult. The following code demonstrates the complete download functionality:

public IActionResult Download(int id)
{
    var pdfFile = _pdfFiles.FirstOrDefault(f => f.Id == id);
    if (pdfFile == null || !System.IO.File.Exists(pdfFile.FilePath))
        return NotFound();
    byte[] fileBytes = System.IO.File.ReadAllBytes(pdfFile.FilePath);
    return File(fileBytes, pdfFile.ContentType, pdfFile.FileName);
}

public IActionResult Download(int id)
{
    var pdfFile = _pdfFiles.FirstOrDefault(f => f.Id == id);
    if (pdfFile == null || !System.IO.File.Exists(pdfFile.FilePath))
        return NotFound();
    byte[] fileBytes = System.IO.File.ReadAllBytes(pdfFile.FilePath);
    return File(fileBytes, pdfFile.ContentType, pdfFile.FileName);
}

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<table>
    @foreach (var item in Model)
    {
        <tr>
            <td>@item.FileName</td>
            <td>@item.UploadedDate</td>
            <td>
                <a href="/Pdf/Download/@item.Id">Download</a>
            </td>
        </tr>
    }
</table>

<table>
    @foreach (var item in Model)
    {
        <tr>
            <td>@item.FileName</td>
            <td>@item.UploadedDate</td>
            <td>
                <a href="/Pdf/Download/@item.Id">Download</a>
            </td>
        </tr>
    }
</table>

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How Do You Create and Download PDF Documents On-Demand?

Beyond storing existing files, you can generate new PDF documents dynamically using IronPDF's HTML-to-PDF conversion. This approach enables creating reports, invoices, or certificates on-demand:

public IActionResult GeneratePdf()
{
    var renderer = new IronPdf.ChromePdfRenderer();
    var PDF = renderer.RenderHtmlAsPdf("<h1>Generated Report</h1><p>Created: " + DateTime.Now + "</p>");
    return File(pdf.BinaryData, "application/pdf", "report.pdf");
}

public IActionResult GeneratePdf()
{
    var renderer = new IronPdf.ChromePdfRenderer();
    var PDF = renderer.RenderHtmlAsPdf("<h1>Generated Report</h1><p>Created: " + DateTime.Now + "</p>");
    return File(pdf.BinaryData, "application/pdf", "report.pdf");
}

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Conclusion

Implementing PDF upload and download functionality in ASP.NET Core combines standard file-handling techniques with IronPDF’s advanced processing capabilities. With the ability to watermark, generate, store, and serve PDF files, your application becomes more robust and user-friendly.

You can integrate further features such as merging documents, adding metadata, filling forms, or generating interactive content. Review IronPDF’s reference documentation or browse new tutorials in our blog for advanced capabilities. Have any following error issues with your code? Check out the helpful troubleshooting guides.

Ready to enhance your ASP.NET Core application with advanced PDF features? Purchase an IronPDF license for production deployment, visit the extensive documentations for additional information, or chat with our team for guidance on your specific project requirements.