Ruby on Rails: conditionally display a partial

Question

I'm not sure if I'm doing the best approach here, but I have a block of data that I want to show after a search is done and to not be there at all before. First of all, there is nothing to show, and second the model it references is nil so it throws an exception.

I placed this block in a partial template and added it the appropriate spot in my layout. Is there a way to cleanly render the partial conditionally? Is there a better way to approach this problem?

Answer 1

Ruby allows you to do nice things like this:

<%= render :partial => "foo/bar" if @conditions %>

To make this a bit easier to read and understand, it can be written as:

<%= render(:partial => "foo/bar") if @conditions %>

render is a function, and you pass it a hash that tells it which partial to render. Ruby allows you to put things on one line (which often makes them more readable and concise, especially in views), so the if @conditions section is just a regular if statement. It can also be done like:

<% if @conditions %>
  <%= render :partial => "foo/bar" %>
<% end %>

Edit:

Ruby also allows you to use the unless keyword in place of if. This makes code even more readable, and stops you from having to do negative comparisons.

<%= render :partial => "foo/bar" if !@conditions %>
#becomes
<%= render :partial => "foo/bar" unless @conditions %>