Destroy data based on HTML class name in Rails - html

Question

I'm building a simple todo list using Rails (3.2.5).
I show all of the users todo items in an unordered list, each list item being the todo itself. By clicking on the todo item the user marks it as completed. Using jQuery I give the li a class of done so I can change its styling. By clicking on a "Clear completed" button I want the completed items to be destroyed (and deleted from the database).
How can this be done?
NB: I'm basically trying to recreate this app using Rails: http://davidpdrsn.com/todos/

Answer 1

You can do it using a remote form
So you would have something like
you would have a form with remote: true for each item or you could have only one form and submit it with JQuery.
class TodoController
def set_completed
#todo = Todo.find(params[:id])
#todo.done = true # you could move this to your model and do something like #todo.done! and that would save it automatically
#todo.save
end
def destroy_completed
#todos_to_delete = Todo.where(done: true)# here you could also move it to your model and do it like Todo.completed
#todos_to_delete.destroy_all
end
end
and you would render the response with the js for formatting, or even removing items on your list, like
views/todo/set_completed.erb.js
$("#item_<%= #todo.id %>").addClass("completed");

Answer 2

Supposing the model is called Todo and the completed column is called completed, you can write one of these in the controller:
Todo.destroy_all(:completed => true)
Todo.where(:completed => true).destroy_all
If you need help with how to manage the ajax request/response, here there is a good start (sorry, I don't want to give you the solution, IMHO you should make your way by yourself)
Resources: ActiveRecord#Base::destroy_all