Upload file using WebApi, ajax

The answer has several parts.

First, to upload the file, you can use a view with code like this:

@using (Html.BeginForm())
{
    <input type="file" value="Choose a file"/>
    <br/>
    <input type="button" value="Upload" id="upload"/>
}

@section scripts
{
<script type="text/javascript">
    $(document).ready(function() {
        $('#upload').click(function () {
            var data = new FormData();
            var file = $('form input[type=file]')[0].files[0];
            data.append('file',file);
            $.ajax({
                url: '/Api/File/Upload',
                processData: false,
                contentType: false,
                data: data,
                type: 'POST'
            }).done(function(result) {
                alert(result);
            }).fail(function(a, b, c) {
                console.log(a, b, c);
            });
        });
    });
</script>    
}

Second, to receive this data, create a controller, with a method like this:

public class FileController : ApiController
{
    [HttpPost]
    public async Task<string> Upload()
    {
       var provider = new MultipartMemoryStreamProvider();
       await Request.Content.ReadAsMultipartAsync(provider);

       // extract file name and file contents
       var fileNameParam = provider.Contents[0].Headers.ContentDisposition.Parameters
           .FirstOrDefault(p => p.Name.ToLower() == "filename");
       string fileName = (fileNameParam == null) ? "" : fileNameParam.Value.Trim('"');
       byte[] file = await provider.Contents[0].ReadAsByteArrayAsync();

       // Here you can use EF with an entity with a byte[] property, or
       // an stored procedure with a varbinary parameter to insert the
       // data into the DB

       var result 
           = string.Format("Received '{0}' with length: {1}", fileName, file.Length);
       return result;
    }
}

Third, by default the maximum upload size is limited. You can overcome this limitations modifying web.config:

1. Add maxRequestLength="max size in bytes" in <configuration><system.web><httpRuntime>. (Or create this lement if it doesn't exist):

2. Add maxAllowedContentLength to <configuration><system.web><security><requestFiltering><requestLimits> element (or create this element if it doesn't exist)

These entries look like this:

<configuration>
  <system.web>
    <!-- kilobytes -->
    <httpRuntime targetFramework="4.5" maxRequestLength="2000000" />

<configuration>
  <system.webServer>
   <security>
    <requestFiltering>
      <!-- bytes -->
      <requestLimits maxAllowedContentLength="2000000000"/>

NOTE: you should include this inside a <location> element, so that this limits are only applied to the particular route where the files are uploaded, like this:

<location path="Api/File/Upload">
  <system.web>
     ...
  <system.webServer>
     ...

Beware to modify the root web.config, not the one in the Views folder.

Fourth, as to saving the data in the database, if you use EF, you simply need an entity like this:

public class File
{
  public int FileId { get; set; }
  public string FileName { get; set; }
  public byte[] FileContent { get; set; }
}

Create a new object of this class, add to the context and save changes.

If you use stored procedures, create one which has a varbinary parameter, and pass the byte[] file as value.

A cleaner way to do this using webAPI controller is as follows:

Create a web api controller file: UploadFileController.cs

public class UploadFileController : ApiController
{
    // POST api/<controller>
    public HttpResponseMessage Post()
    {
        HttpResponseMessage result = null;
        var httpRequest = HttpContext.Current.Request;
        if (httpRequest.Files.Count > 0)
        {
            var docfiles = new List<string>();
            foreach (string file in httpRequest.Files)
            {
                var postedFile = httpRequest.Files[file];
                int hasheddate = DateTime.Now.GetHashCode();
                //Good to use an updated name always, since many can use the same file name to upload.
                string changed_name = hasheddate.ToString() + "_" + postedFile.FileName;

                var filePath = HttpContext.Current.Server.MapPath("~/Images/" + changed_name);
                postedFile.SaveAs(filePath); // save the file to a folder "Images" in the root of your app

                changed_name = @"~\Images\" + changed_name; //store this complete path to database
                docfiles.Add(changed_name);

            }
            result = Request.CreateResponse(HttpStatusCode.Created, docfiles);
        }
        else
        {
            result = Request.CreateResponse(HttpStatusCode.BadRequest);
        }

        return result;
    }
}

To use this webAPI in your markup. Use following:

<input type="hidden" id="insertPicture" />
<input id="insertFileupload" type="file" name="files[]" accept="image/*" data-url="/api/uploadfile" multiple>
<script>
 $(function () {
 $('#insertFileupload').fileupload({
   add: function (e, data) {
     var jqXHR = data.submit()
       .success(function (result, textStatus, jqXHR) {/* ... */
          $('#insertPicture').val(result);
          alert("File Uploaded");
       })
       .error(function (jqXHR, textStatus, errorThrown) {/* ... */
          alert(errorThrown);
       })
    }
  });
});

You can change the type of file (extensions to accept) in the "accept" attribute of the input tag. Hope it will help! Enjoy!