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Thursday, March 4, 2010

Returning a LINQ to SQL Image from ASP.NET MVC

I am working in VS2010 RC at the time of this posting.

I am working with a set of images stored in an SQL database in my ASP.NET MVC project. I would like to load the images asynchronously (and preferably effortlessly) and as “in-line” as possible from my pages. I wanted to create a controller action that returned an image.

Ideally, something that works into my page as simply as this:


The HTML that would be rendered might be like this (or, I could write it out myself if I don’t want to use the Url helper above):


My images were being returned from a LINQ to SQL method (a stored procedure that returned an Image field) and, so, were typed as System.Data.Linq.Binary

A Complicated Mess

I Binged around for a bit but was having trouble finding info that was relevant or entirely up-to-speed with the latest MVC bits. I was frustrated because, without much explanation, people were reverting to complicated HTTP handlers, building System.Drawing.Bitmap objects and subclassing ActionResult (which felt a little weird).

I came up with the following solution (which I wrote in my controller) by gleaning through a ton of different implementations:

public EmptyResult GetImage(int id)
Byte[] imageBytes = _repository.GetImage(id).ToArray();

Response.OutputStream.Write(imageBytes, 0, imageBytes.Length);
Response.ContentType = "image/png";

return new EmptyResult();

This afforded me the simple notational luxuries as listed above, but it felt a little wrong to be pumping out data to the response stream when I’m describing my method as an EmptyResult.

Easier Without Getting Harder

I didn’t want to run into creating inherited types and the likes without a good reason. This was as complicated as I wanted to get and I wanted to know if I should go further.

I posted a question to StackOverflow to that tune and got back a lead on a couple other candidates to work with. A quick lookup on FileContentResult and I was off to the races:


If you like (and to facilitate testing) you can also easily implement a subclass of FileContentResult and pre-set the image type; then all you’d be doing is returning a new PngResult(byteshere).

To Be Fair…

I don’t mean to condemn any of the earlier efforts. In fact, some were pretty ingenious considering the state of MVC over a year ago.

The types that are available now in ASP.NET MVC make it very easy to return an image from a controller action, even if that image is a byte array or stored as a LINQ Binary type.

1 comment:

  1. Thanks for this, it helped med with my issues!