What is the correct way to declare an asmx Webmethod in C# to receive POST requests with parameters?

Question

I’m trying to set up a file upload process for a web service done on c# .asmx, but I am not able to manipulate the sending of parameters through the method POST.

This is the webMethod I created:

[WebMethod]
[SoapHeader("UserAuthentication")]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public void UploadFiles(string token)
{
    CheckHeader();
    if (!(Context.Request.Files.Count > 0))
        return;
    var path = (UserAuthentication.Usuario.Login + token).GetHashCode();
    var directory = DiretorioPublicacaoArquivos();

    foreach (string fileItem in Context.Request.Files.AllKeys) {
        var file = Context.Request.Files[fileItem];

        if (Strings.IsPopulated(file.FileName)) {
            var dirInfo = new DirectoryInfo(directory + @"\temp\" + path+ @"\");
            if (!dirInfo.Exists)
                dirInfo.Create();

            var fileInfo = new FileInfo(dirInfo.FullName + file.FileName);
            if (fileInfo.Exists)
                fileInfo.Delete();

            file.SaveAs(fileInfo.FullName);
        }
    }
}

The parameter token is an identifier I will receive from client to be able to create a temporary directory where the files will be stored as they are received.

So in the client, using the jquery.uploadfile, mount the form to upload the files:

<div id="upload">Selecionar Arquivos</div>

$("#upload").uploadFile({
    url: "/Services/PublicacaoService.asmx/UploadFiles",
    method: "post",
    fileName: "myfile",
    dynamicFormData: function () {
        var data = { token: "123 testando" };
        return data;
    },
    multiple: true,
});

According to the plugin documentation, I can use both the method dynamicFormData as the attribute formData, passing my parameter directly to it.

Example:

$('#fileupload').fileupload({
    formData: {example: 'test'}
});

I’ve tried both ways, but I can’t send files when I need to pass a parameter to webMethod. What happens is that the attached files soon return a Internal Server Error.

However, just take the parameter from the header of the webMethod and I can already get the break-point, added within the webMethod for debug, is activated.

[WebMethod]
[SoapHeader("UserAuthentication")]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public void UploadFiles() // <-- sem o parâmetro
{ 
    ... 
}

Inlusive, manipulating to play in another folder that does not depend on the token, works. Of course that’s not how I need it, it’s only for tests.

How to solve this?
What is the correct way to declare the Webmethod to receive the requests by the POST method and with parameters?

Answer 1

There was nothing wrong with your method. So much so that if you test with :

  <script>
        $(document).ready(function () {
             $.ajax(
              {
                   url: "/Services/PublicacaoService.asmx/UploadFiles",
                   contentType: "application/json; charset=utf-8",
                   enctype: 'multipart/form-data',
                   dataType: "json",
                   type: "POST",
                   data: "{token:'test'}"
               });
        });
    </script>

You will see that your method will stop at your break point.

For this plugin, I suggest you change your Uploadfiles method to the following :

public void UploadFiles()
{
    var token = HttpContext.Current.Request.Form.Get("token");
    CheckHeader();
    if (!(Context.Request.Files.Count > 0))
    //Continuação do seu código
}

In the plugin when you use dynamicFormData the token is added in the form, and then you can recover on the server side using Httpcontext.Current.Request.Form.Get("token");

The Internal Server Error you were probably getting was this error :

System.Invalidoperationexception: Request format invalid: Multipart/form-data; Boundary=---blahblahblah