C# Edit objects in linq expression in asp.net-mvc

Question

Lets say I have the following code:

return (from p in repository.GetPostMedia() select p).ToList();

But in the values of object p, I want to inject a property calculated as follows:

MediaUrl = App.Resource["MediaPath"] + p.Id + "." + p.Ext;

PS. This code is located in the Service section of an ASP.NET MVC application. It is supposed to generate a url property and attach it to the returned object. If the controller is the best place to put this logic, how would I accomplish this with my code as follows:

public ActionResult PostMediaList(int postId)
{
  var media = postService.GetMedia(); //the call to the code above.

  return Json(media);
}

Media is generated from the LINQ to SQL in the repository. Also, i want to be able to change the path of where the media files are stored at a later date and just change something web project or service project only.

Answer 1

From what I understand of your question, you could return an anonymous type instead of whatever p is.

return (from p in repository.GetPostMedia()
        select new { Media = p,
                     MediaUrl = App.Resource["MediaPath"] + p.Id + "." + p.Ext } ).ToList();

Answer 2

Create a wrapper class with the property you want, and return a collection of that class with your query.

Very, very basic and skeletal example:

class MyMedia
{
    public MyMedia(Media m)
    {
        this.Media = m;
        this.MediaUrl = App.Resource["MediaPath"] + m.Id + "." + m.Ext;
    }

    public Media Media
    {
        get; set;
    }

    public string MediaUrl
    {
        get; set;
    }
}

and then, in your method:

return (from p in repository.GetPostMedia() select new MyMedia(p)).ToList();