Rails clone copy or duplicate - ruby-on-rails-3

Question

I have a nested form and once I save, I want to be able to click a link on the show page to copy or clone that form and open a new one. From there I should be able to make edits (like a new id) and save as a new record. I have seen some examples like this deep_cloneable gem, but I have no idea how to implement it. I think this should be simple, but I just don't understand where to put things in the controller and in the show view.

Answer 1

If you want to copy an activeRecord object you can use its attributes to create new one like
you can have an action in your controller which can be called on link,
def create_from_existing
#existing_post = Post.find(params[:id])
#create new object with attributes of existing record
#post = Post.new(#existing_post.attributes)
render "your_post_form"
end

Answer 2

I found these answers a little hard to follow. One answer shows this:
#post = Post.new(#existing_post.attributes)
which will not work as it will also pass the id, and timestamp values. I used .dup to fix that and I show that in my answer.
Here's how I achieved creating a new item from an existing item.
The model is for a Product, the controller Products_Controller.rb. We're going to add a new action to the controller called copy and we're going to link to it from the show view on an existing Product and render a filled out new view ready to be edited and saved.
First we create a route for the copy action in routes.rb
# Routes.rb
resources :Products do
member do
get 'copy'
end
end
Then a copy action in Products_controller.rb
# ProductController.rb
def copy
#source = Product.find(params[:id])
#product = #source.dup
render 'new'
end
Now we need to add a Link to the show view to call our copy action.
# show.html.erb
<%= link_to "copy", copy_product_path(params[:id]) %>
Rails 4-6 Update:
The strong parameter scaffold makes it even shorter:
# ProductController.rb
# GET /products/1/copy
def copy
#product = #product.dup
render :new
end
And in the erb template:
# show.html.erb
<%= link_to "copy", copy_product_path(#product) %>

Answer 3

class Foo < ActiveRecord::Base
def self.clone_from(parent)
parent = find(parent) unless parent.kind_of? Foo
foo = self.new
foo.attributes = parent.attributes
# if you want to also clone a habtm:
foo.some_association_ids = parent.some_association_ids
# etc.
foo
end
end
class FoosController < ApplicationController
def clone
foo = Foo.clone_from(params[:id])
respond_with(foo)
end
end

Answer 4

Also worth mentioning is the dup method on a model. It makes a copy with all attributes and outgoing relations but sets id to nil. Like this (borrowing code from Naren Sisodiya):
def create_from_existing
#existing_post = Post.find(params[:id])
#create new object with attributes of existing record
#post = #existing_post.dup
render "your_post_form"
end