Resort provides sorting capabilities to your Rails models.
$ gem install resort
Or in your Gemfile:
Most other sorting plugins work with an absolute
position attribute that sets
the weight of a given element within a tree. This field has no semantic sense,
since "84" by itself gives you absolutely no information about an element's
position or its relations with other elements of the tree.
Resort is implemented like a linked list,
rather than relying on absolute position values. This way, every model
next element, which seems a bit more sensible :)
First, run the migration for the model you want to Resort:
$ rails generate resort:migration product $ rake db:migrate
Then in your Product model:
class Product < ActiveRecord::Base resort! end
NOTE: By default, Resort will treat all products as a single big tree.
If you wanted to limit the tree scope, i.e. treating every ProductLine as a
separate tree of sortable products, you must override the
class Product < ActiveRecord::Base resort! def siblings # Tree contains only products from my own product line self.product_line.products end end
Multiple users modifying the same list at the same time could be a problem, so it's always a good practice to wrap the changes in a transaction:
Product.transaction do my_product.append_to(another_product) end
Every time a product is created, it will be appended after the last element.
Moreover, now a
product responds to the following methods:
first?— Returns true if the element is the first of the tree.
append_to(other_element)— Appends the element after another element.
prepend— Moves the element to the beginning of the list (sets it as first).
next— Returns the next element in the list.
previous— Returns the previous element in the list.
And the class Product has a new scope named
ordered that returns the
products in order.
Product example defined before, we can do things like:
Getting products in order:
Product.first_in_order # returns the first ordered product. Product.last_in_order # returns the last ordered product. Product.ordered # returns all products ordered as an Array, not a Relation!
Find ordered products with scopes or conditions:
Product.where('price > 10').ordered # => Ordered array of products with price > 10 Product.with_custom_scope.ordered # => Ordered array of products with your custom conditions
Modify the list of products:
product = Product.create(:name => 'Bread') product.first? # => true another_product = Product.create(:name => 'Milk') yet_another_product = Product.create(:name => 'Salami') yet_another_product.append_to(product) # puts the products right after the first one Product.ordered.map(&:name) # => ['Bread', 'Salami', 'Milk']
product = Product.create(:name => 'Bread') second_product = Product.create(:name => 'Milk') third_product = Product.create(:name => 'Salami') second_product.previous.name # => 'Bread' second_product.next.name # => 'Salami' third_product.next # => nil
Maybe you need different orders depending on the product vendor:
class Product < ActiveRecord::Base resort! belongs_to :vendor def siblings self.vendor.products end end bread = Product.create(:name => 'Bread', :vendor => Vendor.where(:name => 'Bread factory')) bread.first? # => true milk = Product.create(:name => 'Milk', :vendor => Vendor.where(:name => 'Cow world')) milk.first? # => true # bread and milk aren't neighbours
Under the hood
Run the test suite by typing:
You can also build the documentation with the following command:
Note on Patches/Pull Requests
- Fork the project.
- Make your feature addition or bug fix.
- Add tests for it. This is important so I don't break it in a future version unintentionally.
- Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)
- Send us a pull request. Bonus points for topic branches.
Copyright (c) 2011 Codegram. See LICENSE for details.