How to return a file to the client?

Question

I need to return a file in my action so that the client can download it. In my current code, the file is being saved on server.

[HttpGet]
public JsonResult ExibirPrintRPA(int? id)
{
    string _nameFile = string.Empty;
    EmissaoPrintRPA lemissao = new EmissaoPrintRPA();
    EmissaoPrintRPA emissaoPrints = _EmissaoPrintRPAApplicationService.GetById(lemissao);           
    var _imagem = emissaoPrints.ST_IMAGEM;
    _imagem = _imagem.Replace(" ", "+");
    int mod4 = _imagem.Length % 4;
    if (mod4 > 0)
    {
        _imagem += new string('=', 4 - mod4);
    }

    var _img = Convert.FromBase64String(_imagem);
    var _filePath = string.Format("{0}\\{1}.{2}", 
        Server.MapPath("~/Files/Downloads"), _nameFile, "jpeg");
    using (var fs = new FileStream(_filePath, FileMode.Create))
    {
        fs.Write(_img, 0, _img.Length);                
        fs.Flush();               
    }

    return Json(new 
    { 
        file = string.Format("{0}.{1}", _nameFile, "jpeg"), 
        path = _filePath 
    });
}

Answer 1

Instead of trying to salvage a file, you need to return that file to the caller of your action.

This can be done using the method File().

I don’t quite understand this manipulation you made before Convert.FromBase64String, but I’m assuming she’s right.

As the method Convert.FromBase64String already returns a array of bytes, you can simply pass it to the method File.

Note that you need to inform as the second parameter the content type of the file and, as the third parameter, its name.

[HttpGet]
public ActionResult ExibirPrintRPA(int? id)
{
    string _nameFile = string.Empty;

    EmissaoPrintRPA lemissao = new EmissaoPrintRPA();
    EmissaoPrintRPA emissaoPrints = _EmissaoPrintRPAApplicationService.GetById(lemissao);           

    var _imagem = emissaoPrints.ST_IMAGEM;
    _imagem = _imagem.Replace(" ", "+");

    int mod4 = _imagem.Length % 4;

    if (mod4 > 0)
    {
        _imagem += new string('=', 4 - mod4);
    }

    var bytesImagem = Convert.FromBase64String(_imagem);

    return File(bytesImagem, "ContentTypeArquivo", "NomeArquivo");
}