Question

Here is the trick. I have a model called Pages with a field called “page_type” wich can be one of, lets say, 3 variants: “html”, “image”, “vcard”, and a field called “content”.
So now I need the app to respond with different mimetypes depending on what type of a page is requested.

If the page_type is set to “html” – render the content as html using the appropriate view and html_safe, that’s easy.

If the page_type is set to “image” – get the image, using the path, stored in the content and send it back to the user as if he requested an image.

Same for “vcard”.

How can I do that?

Answer 1

If you’re generating the URLs to access your resources (Page) in your app, you can specify the resource location RESTfully, such as /pages/2.jpg, /pages/3.vcard, /pages/4 (default is html) using the built-in Rails view helpers such as page_url(@page, :format => ‘jpg’). Then it’s simply a matter of using repond_to in Rails to deliver the resource:

respond_to do |format|
  format.html { # default rendering in show.erb.html }
  format.jpg { # perhaps send_file or send_data call }
  format.vcard { # send attachment }
end

Check out the Rails Routing Guides for more info. You’ll need to configure Rails to handle requests for .vcard. See this gist.

If you don’t control link generation (external references to your resources) and expect to get requests like /pages/2 (which is a jpeg), then you’ll have to fall back to using your page_type column to conditionally render with send_file, send_data, or other Rails rendering methods. You might consider re-using the logic (methods) you create for each block in respond_to above, so that your controller has ‘respond_to_html’, ‘respond_to_jpg’, ‘respond_to_vcard’ methods.