Web Api 2 RESTFUL Image Upload

Question

I'm new in Web Api and I'm working on my first project. I'm working on mobile CRM system for our company.

I want to store companies logo, customers face foto etc.

I found some tutorials on this topic, but unfortunately some of them was old (doesn't use async) and the others doesn't work.

At the end I found this one: http://www.intstrings.com/ramivemula/articles/file-upload-using-multipartformdatastreamprovider-in-asp-net-webapi/ It works correctly, but I don't understand a few things.

1) Should I use App_Data (or any other folder like /Uploads) for storing this images, or rather store images in database?

2) Can I set only supported images like .jpg, .png and reject any other files?

3) How can I processed image in upload method? Like resize, reduce size of the file, quality etc?

Thank you

Solution 1

None of the questions are actually related to Web API or REST.

1. If you are using SQL Server 2008 or newer the answer is use FILESTREAM columns. This looks like a column in database with all its advantages (i.e. backup, replication, transactions) but the data is actually stored in file system. So you get the best of each world, i.e. it will not happen that someone deletes the file accidentally so database will reference an inexistent file, or vice versa, records from database are deleted but files not so you'll end up with a bunch of orphan files. Using a database has many advantages, i.e. metadata can be associated with files and permissions are easier to set up.
2. This depends on how files are uploaded. I.e. if using multipart forms then examine content type of each part before part is saved. You can even create your own MultipartStreamProvider class. Being an API maybe the upload method has a stream or byte array parameter and a content type parameter, in this case just test the value of content type parameter before content is saved. For other upload methods do something similar depending on what the input is.
3. You can use .Net's built in classes (i.e. Bitmap: SetResolution, RotateFlip, to resize use a constructor what accepts a size), or if you are not familiar with image processing rather choose an image processing library.

All of the above work in Asp.Net, MVC, Web API 1 and 2, custom HTTP handlers, basically in any .Net code.

Solution 2

1) We are storing files in a different location than app_data. We have a few customer groups and we gave them all a unique folder that we get from the database. Storing in database is also an option but if you go down this road, make sure that the files you are saving don't belong directly to a table that you need to retrieve often. There is no right or wrong, but have a read at this question and answer for some pros and cons.

2) If you foollowed that guide, you can put a check inside the loop to check the file ending

List<string> denyList = new List<string>();
denyList.Add(".jpg");

foreach (MultipartFileData file in provider.FileData) 
{
    string fileName = Path.GetFileName(file.LocalFileName);
    if(denyList.Contains(Path.GetExtension(fileName))
         throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);

    files.Add(Path.GetFileName(file.LocalFileName)); 
}

3) Resizing images is something that I have never personally done my self, but I think you should have a look at the System.Drawing.Graphics namespace. Found a link with an accepted answer for downresize of picture: ASP.Net MVC Image Upload Resizing by downscaling or padding