检查红宝石哈希中的密钥是否可用

Question

I have a partial named test in rails and I am sending some data in locals hash, I need to check if title exists in locals hash.

<%= render partial: "/test", :locals => {
        :title  => "sample title"
      } 
      %>

I tried with

locals.has_key? 'title',

But it is not working. Can any one help in this?

Answer 1

I need to check if title exists in locals hash.

Well, for that you have to do local_assigns.has_key? :some_local local_assigns.has_key? :some_local .

<% if local_assigns.has_key?(:some_local) %>
  <%= some code here %>
<% end %>

I didn't get the documentation from Rails guide, but I knew this feature, that's why I mentioned it here. But here are some discussions on 15700 and 18970 about local_assigns on guides.

Finally with the help of @stefan I found out the documentation of the method local_assigns .

Answer 2

You need to write title as string ,not as symbol

<%= render partial: "/test", :locals => {"title"  => "sample title" } %>

Now locals.has_key? "title" locals.has_key? "title" will return true

For reference see this SO

Answer 3

You can write

<%= render '/test', title: 'sample title' %>

Within the locale you do this:

if defined?(title) 
  ...
end

Answer 4

It's because 'title' and :title are separate keys. You can use :title or 'title'.to_sym instead.