When using JavaScript (AJAX) to request a file, the browser does not automatically trigger a download dialog. You must handle the response by creating a temporary "Blob" object and a hidden link to simulate a click.
If you are developing a desktop or console application, you can use the System.IO namespace to write the byte array directly to a physical file on the system. download pdf from byte array c#
using System.IO; byte[] pdfBytes = GetPdfByteArrayFromSource(); string filePath = @"C:\Downloads\MyFile.pdf"; // Writes the entire byte array to the specified path File.WriteAllBytes(filePath, pdfBytes); Use code with caution. Advanced Scenarios: AJAX and Client-Side Downloads When using JavaScript (AJAX) to request a file,
[HttpGet] public IActionResult DownloadPdf() { // Retrieve your byte array (e.g., from a database or service) byte[] pdfBytes = GetPdfByteArrayFromSource(); // Return the file using the application/pdf MIME type // Providing a filename triggers a browser download return File(pdfBytes, "application/pdf", "GeneratedDocument.pdf"); } Use code with caution. using System
Use a library or vanilla JavaScript to handle the binary response: Ensure the request's responseType is set to blob . Create a URL for the blob using URL.createObjectURL(blob) .
For large files, you can wrap the byte array in a MemoryStream and use FileStreamResult to improve memory efficiency. Saving a Byte Array to Disk (Console Apps)