Rails 4 - Render STI models from a common partial - ruby-on-rails

Question

I have STI models like this : Photo < Medium and Video < Medium.
Somewhere in a view, i would like to show them like that :
# app/views/albums/show.html.slim
ul
li= render #album.media
The render search for a albums/_photo or albums/_video partial :
# app/views/albums/_photo.html.slim
h3= photo.title
= image_tag photo.file.url
p= photo.description
# app/views/albums/_video.html.slim
h3= video.title
= video_tag video.file.url
p= video.description
Now, i would like to make a template to use in app/views/albums/show.html.slim for not repeat commons fields between media. Something like that :
# app/views/albums/_medium.html.slim
h3= medium.title
= yield(:medium_tag)
p= medium.description
= yield(:medium_additionnals)
# app/views/albums/_photo.html.slim
- content_for(:medium_tag) do
= image_tag photo.file.url
- content_for(:medium_additionnals) do
# any additionnals fields
# app/views/albums/_video.html.slim
- content_for(:medium_tag) do
= video_tag video.file.url
- content_for(:medium_additionnals) do
# any additionnals fields
But this give me in yields concatenate contents...
Someone has a solution / alternative to do this ?
[EDIT]
With this templates :
# app/views/albums/show.html.slim
= render #album.media
# app/views/albums/_medium.html.slim
div
h3= medium.title
= yield(:medium_tag)
# app/views/albums/_photo.html.slim
- content_for(:medium_tag) do
| TEST
The resulting HTML :
<div>
<h3>Photo1</h3>
TEST
</div>
<div>
<h3>Photo2</h3>
TESTTEST
</div>
<div>
<h3>Photo3</h3>
TESTTESTTEST
</div>
<div>
<h3>Photo4</h3>
TESTTESTTESTTEST
</div>
...
The yield result is concatened as many time as media count.

Answer 1

Your code seems really good, although I don't get how your render call is cycling through each medium item
You could use a helper to return the relevant data, although that wouldn't be the most efficient:
#app/helpers/application_helper.rb
module ApplicationHelper
output = Slim::Engine.new "h3={item.title}"
output += Slim::Engine.new "- eval(#{item.model_name.human}_tag) item.file.url"
output += Slim::Engline.new "p=item.description"
end
end
This would allow you to run:
#app/views/albums/_photo.html.slim
= media photo
#app/views/albums/_video.html.slim
= media video
-
Alternatively, you could just put it into a _medium partial:
#app/views/albums/_photo.html.slim
= render partial: "medium", locals: { item: photo }
#app/views/albums/_video.html.slim
= render partial: "medium", locals: { item: video }
_medium would then have the following:
#app/views/albums/_medium.html.slim
h3=item.title
- eval("#{item.model_name.human}_tag") item.file.url
p=item.description