How to pass some parameters to the default rendering method?

Question

I am using Ruby on Rails 3.0.10 and I would like to pass some parameters to the default rendering method. That is, if I have a code like

def show
  ...

  respond_to do |format|
    format.html # This, by default, renders the 'show.html.erb' file
   end
end

I would like to pass some parameters, maybe like (note: the following doesn't work)

def show
  ...

  respond_to do |format|
    # Here I would like to add some local objects that will be available in the 'show.html.erb' template file
    format.html { render ..., :locals => { :content => { :value => 'Sample value' } } }
   end
end

so that in the show.html.erb template I can make something like:

<%=
  content[:value]
  # => 'Sample value'
%>

In few words, I would like to pass parameter values in the same way as made for partial template rendering related to the :locals key:

render :partial, 
       :locals => {
          :content => { :value => 'Sample value' }
       }

How can I do that?

Answer 1

You can do exactly what you described. I looked it up here http://apidock.com/rails/ActionController/Base/render under the heading "Rendering a template" and gave it a whirl myself. You learn something new everyday.

You can simply do

def show
  respond_to do |format|
    format.html { render :locals => { :content => { :value => 'Sample value' } } }
  end
end

I would consider why you need to do this instead of using instance variables. Maybe there is a better approach.

Answer 2

How about setting an instance variable?

# your_controller.rb

def show
  @content_value = ...
end

 

# show.html.erb

<%= @content_value %>

Answer 3

Usually when we're working with actions show.html.erb is an action view rather than a partial view, we're passing parameters via instance variables on the controller such as

def show
  ...
  @foo = "bar"
  respond_to do |format|
    format.html
   end
end

Now in the app/views/foos/show.html.erb file, we have access to @foo.

When rendering partials, there are a few ways to pass parameters:

This will render partial app/views/foos/_foo.html.erb by default because it knows @foo is of type Foo. In it, you will have access to a foo variable automatically.

<%= render @foo %>

Here we will render app/views/foos/_foo_details.html.erb, and pass in an object. The object takes the name of the partial, so inside _foo_details.html.erb we'll have access to a variable called foo_details.

<%= render :partial => "foo_details", :object => @foo %>

Finally, and mostly related to your question, we'll render a partial called _foo_things.html.erb and pass it some locals. In this case, you'd get a local variable called title which you could work with.

<%= render :partial => "foo_things", :locals => {:title=> "Test 123"} %>

I hope that answers your question.