Dynamic rendering of partials in Rails 3 - ruby-on-rails

Question

In the app I'm working on, I have defined a method task_types in the model:
task.rb
def self.task_types
["ad_hoc"]
end
I use task_types to populate a drop-down menu, but I would also like to use it to dynamically render a partial.
What I have in mind is, for each task type, there will be an associated comment box. I went ahead and made a helper that will call the correct partial depending upon which task type was selected:
#tasks_helper.rb
module TasksHelper
def completion_comment(task)
task_types = #task.task_type
render :partial => "#{Task.task_types}", :locals => {:task => task}
end
end
Unfortunately, when I called completion_comment, I received the error message "The partial name (["ad_hoc"]) is not a valid Ruby identifier."
What I'm looking for is a dynamic way to render the appropriate partial. I think I'm on the right track, but I'm not sure how to extract the array elements from my task_types method (as you can see in the error message, the brackets and quotation marks are getting pulled into the render action). Or, perhaps I need to utilize a different method for dynamically rendering the partial. Any help is appreciated.

Answer 1

Here's what worked:
module TasksHelper
def render_task_form(task)
render :partial => "/tasks/completed/#{task.task_type.downcase}"
end
end
I had tried this solution much earlier, and had received an error that "The partial name (/tasks/completed/) is not a valid Ruby identifier; make sure your partial name starts with a letter or underscore, and is followed by any combinations of letters, numbers, or underscores."
I tried it again, and to remedy this problem I deleted all tasks from the database. Now the partial renders dynamically. Hopefully this helps someone else!

Answer 2

You need a string instead of the entire task_types array. #task.task_type should return a key that a) matches an element in the task types array and b) matches a known partial.
The following is a bit more complicated that it needs to be but should do the trick:
tasks_helper.rb
module TasksHelper
def completion_comment(task)
if Task.task_types.include? task.task_type
render :partial => task.task_type,
:locals => {
:task => task
}
else
# render a generic comment box here
end
end
end

Answer 3

In Rails 4, the view or the partial name is supposed to respond to a valid Ruby identifier.
So, the entire view name must follow the same format as a ruby-identifier:
it should start with a _ or character
it cannot start with a number
it can have only _ and alphanumerics.
So, considering that task_type is a valid ruby identifier (which it should be), it will work. In generate this code will not work in Rails 4
render '/tasks/completed/some-task'
but this will work
render '/tasks/completed/some_task' # note the underscore.