How do I get this case statement to work? - ruby-on-rails

Question

In my view, I am doing this:
<% case #post
when #post.has_children? %>
<% #post.children.each do |child| %>
<li><%= link_to child.title, post_path(child)%></li>
<% end %>
<% when #post.has_siblings? %>
<% #post.siblings.where.not(id: #post.id).each do |sibling| %>
<li><%= link_to sibling.title, post_path(sibling)%></li>
<% end %>
<% when !#post.parent.nil? %>
<li><%= link_to #post.parent.title, post_path(#post.parent) %></li>
<% else %>
</ul>
</p>
<p>
There are no related posts.
</p>
<% end %>
Basically what I want to do is I want to check #post for a variety of conditions. If it has_children?, if it has_siblings?, etc.
I don't want the statement to exit if any of the above is true or false.
Once the view loads, it should automatically check for all of these statements. If it finds any of the above true, it should execute the command right below the check.
The issue is when I do this, it always defaults to the else. i.e. the case statement doesn't work.
I know I could simply just do a bunch of disjointed if statements, but then the HTML around it gets a bit weird.
Is there a way I can do this with a CASE statement?
Edit 1
The reason the if statement doesn't work properly, is if I have 3 if statements back to back - none of which that interact with each other (that's the only way to cycle through all of the conditions properly), is that the else doesn't trigger properly.
E.g. if the first two conditions are true, but the third is not...it will print out "there are no related posts"...when that's not the case. It is the case that there are no parent posts.
Basically I just want to have a catch-all related posts, so I am simply iterating through all of the various options and checking to see if those relations exist. If they do, I am pulling them out and if they don't then they move on. If none exist, then I don't print "there are no related posts".

Answer 1

The fact that the view is already looking looking complex is a sign that it may be a good idea to refactor the logic out of the view and place it into the Post model where it belongs. Ideally the view(s) should end up looking like this:
<%# posts/show.html.erb %>
<% if #post.has_related_posts? %>
<%= render partial: 'children', collection: #post.children, as: :child %>
<%= render partial: 'siblings', collection: #post.other_siblings, as: :sibling %>
<%= render partial: 'parent', locals: {parent: #post.parent}%>
<% else %>
<p>There are no related posts</p>
<% end %>
The paritals:
<%# posts/_children.html.erb %>
<li><%= link_to child.title, post_path(child)%></li>
<%# posts/_sibling.html.erb %>
<li><%= link_to sibling.title, post_path(sibling)%></li>
<%# posts/_parent.html.erb %>
<% unless parent.nil? %>
<li><%= link_to parent.title, post_path(parent) %></li>
<% end %>
Then the Post model can organize the logic:
class Post < ActiveRecord::Base
def has_related_posts?
!children.to_a.empty? || !other_siblings.to_a.empty? || !parent.nil?
end
def children
self.children || [] # Rails does this automatically, but just for the example
end
def other_siblings
self.siblings.where.not(id: self.id)
end
#...
end
I know this doesn't directly answer your question, however IMHO I think it's a better solution.

Answer 2

You have two options here.
Use IF ELSIF
<% if #post.has_children? %>
<% #post.children.each do |child| %>
<li><%= link_to child.title, post_path(child)%></li>
<% end %>
<% elsif #post.has_siblings? %>
<% #post.siblings.where.not(id: #post.id).each do |sibling| %>
<li><%= link_to sibling.title, post_path(sibling)%></li>
<% end %>
<% elsif !#post.parent.nil? %>
<li><%= link_to #post.parent.title, post_path(#post.parent) %></li>
<% else %>
</ul>
</p>
<p>
There are no related posts.
</p>
<% end %>
Use only case as doz mentioned
<% case
when #post.has_children? %>
<% #post.children.each do |child| %>
<li><%= link_to child.title, post_path(child)%></li>
<% end %>
<% when #post.has_siblings? %>
<% #post.siblings.where.not(id: #post.id).each do |sibling| %>
<li><%= link_to sibling.title, post_path(sibling)%></li>
<% end %>
<% when !#post.parent.nil? %>
<li><%= link_to #post.parent.title, post_path(#post.parent) %></li>
<% else %>
</ul>
</p>
<p>
There are no related posts.
</p>
<% end %>

Answer 3

You can do it with a case statement. Just give case no parameter. Eg instead of case #post just use case
This is the equivalent of an if statement. And should work for what your trying to achieve
Check out ruby case statements for some examples