Cómo cargar y descargar archivos PDF en ASP .NET C# con IronPDF

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 Property Id As Integer
    Public Property FileName As String
    Public Property ContentType As String
    Public Property FileData As Byte()
    Public Property UploadedDate As DateTime
End Class

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");
    }
}
}

Imports System
Imports System.IO
Imports System.Threading.Tasks
Imports Microsoft.AspNetCore.Http
Imports Microsoft.AspNetCore.Mvc

Namespace UploadPdfs.Controllers
    Public Class PdfController
        Inherits Controller

        Private ReadOnly _context As ApplicationDbContext

        Public Sub New(context As ApplicationDbContext)
            _context = context
        End Sub

        <HttpPost>
        Public Async Function Upload(file As IFormFile) As Task(Of IActionResult)
            If file Is Nothing OrElse file.Length = 0 Then
                Return BadRequest("No file selected")
            End If

            Using stream As New MemoryStream()
                Await file.CopyToAsync(stream)
                Dim pdfFile As New PdfFileModel With {
                    .FileName = file.FileName,
                    .ContentType = file.ContentType,
                    .FileData = stream.ToArray(),
                    .UploadedDate = DateTime.Now
                }
                _context.PdfFiles.Add(pdfFile)
                Await _context.SaveChangesAsync()
            End Using

            Return RedirectToAction("Index")
        End Function
    End Class
End Namespace

[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");
 }

Imports System
Imports System.IO
Imports System.Threading.Tasks
Imports Microsoft.AspNetCore.Http
Imports Microsoft.AspNetCore.Mvc
Imports IronPdf

<HttpPost>
Public Async Function UploadWithWatermark(file As IFormFile) As Task(Of IActionResult)
    If file Is Nothing OrElse file.Length = 0 Then
        Return BadRequest("No file selected")
    End If

    ' 1. Read the uploaded file into a byte array
    Using stream As New MemoryStream()
        Await file.CopyToAsync(stream)
        Dim fileBytes As Byte() = stream.ToArray()

        ' 2. Process with IronPDF (Apply Watermark)
        Dim pdf As New PdfDocument(fileBytes)
        pdf.ApplyWatermark("<h2 style='color:red'>CONFIDENTIAL</h2>", 60, Editing.VerticalAlignment.Middle, Editing.HorizontalAlignment.Center)

        ' 3. Define the new file name and path
        Dim uniqueFileName As String = Guid.NewGuid().ToString() & "_" & file.FileName
        Dim filePath As String = 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)
        Dim pdfFile As New PdfFileModel With {
            .Id = _nextId,
            .FileName = file.FileName,
            .ContentType = "application/pdf",
            .FilePath = filePath, ' Store the physical path
            .UploadedDate = DateTime.Now
        }
        _nextId += 1
        _pdfFiles.Add(pdfFile)
    End Using

    Return RedirectToAction("Index")
End Function

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 Function Download(id As Integer) As IActionResult
    Dim pdfFile = _pdfFiles.FirstOrDefault(Function(f) f.Id = id)
    If pdfFile Is Nothing OrElse Not System.IO.File.Exists(pdfFile.FilePath) Then
        Return NotFound()
    End If
    Dim fileBytes As Byte() = System.IO.File.ReadAllBytes(pdfFile.FilePath)
    Return File(fileBytes, pdfFile.ContentType, pdfFile.FileName)
End Function

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");
}

Imports IronPdf

Public Function GeneratePdf() As IActionResult
    Dim renderer As New ChromePdfRenderer()
    Dim PDF = renderer.RenderHtmlAsPdf("<h1>Generated Report</h1><p>Created: " & DateTime.Now & "</p>")
    Return File(PDF.BinaryData, "application/pdf", "report.pdf")
End Function