test.cs

[HttpPost]
public IActionResult SaveTemplate([FromBody] string document, [FromQuery] string templateName)
{
    if (string.IsNullOrEmpty(document) || string.IsNullOrEmpty(templateName))
    {
        return BadRequest("Invalid input: Document and template name must be provided.");
    }

    try
    {
        // Convert base64 string to byte array
        byte[] bytes = Convert.FromBase64String(document);

        // Ensure the directory exists
        string directoryPath = Path.Combine("Templates");
        if (!Directory.Exists(directoryPath))
        {
            Directory.CreateDirectory(directoryPath);
        }

        // Safely combine the path and template name
        string filePath = Path.Combine(directoryPath, templateName);

        // Save the document to a file
        System.IO.File.WriteAllBytes(filePath, bytes);

        // Return JSON with the file name
        return Json(new { templateName = templateName });
    }
    catch (FormatException)
    {
        return BadRequest("Invalid base64 string.");
    }
    catch (IOException ex)
    {
        return StatusCode(500, "Error saving the file.");
    }
    catch (Exception ex)
    {
        return StatusCode(500, "An unexpected error occurred.");
    }
}