Rails model without database
There is a better way to do this in Rails 3: http://railscasts.com/episodes/219-active-model
activerecord
Rails 3 ActiveRecord: Order by count on association
Using named scopes: class Song has_many :listens scope :top5, select(“songs.id, OTHER_ATTRS_YOU_NEED, count(listens.id) AS listens_count”). joins(:listens). group(“songs.id”). order(“listens_count DESC”). limit(5) Song.top5 # top 5 most listened songs
UNION query with codeigniter’s active record pattern
CodeIgniter’s ActiveRecord doesn’t support UNION, so you would just write your query and use the ActiveRecord’s query method. $this->db->query(‘SELECT column_name(s) FROM table_name1 UNION SELECT column_name(s) FROM table_name2’);
ActiveRecord.find(array_of_ids), preserving order
Oddly, no one has suggested something like this: index = Something.find(array_of_ids).group_by(&:id) array_of_ids.map { |i| index[i].first } As efficient as it gets besides letting SQL backend do it. Edit: To improve on my own answer, you can also do it like this: Something.find(array_of_ids).index_by(&:id).slice(*array_of_ids).values #index_by and #slice are pretty handy additions in ActiveSupport for arrays and hashes … Read more
ActiveRecord Query Union
Here’s a quick little module I wrote that allows you to UNION multiple scopes. It also returns the results as an instance of ActiveRecord::Relation. module ActiveRecord::UnionScope def self.included(base) base.send :extend, ClassMethods end module ClassMethods def union_scope(*scopes) id_column = “#{table_name}.id” sub_query = scopes.map { |s| s.select(id_column).to_sql }.join(” UNION “) where “#{id_column} IN (#{sub_query})” end end end … Read more
How to do a LIKE query in Arel and Rails?
This is how you perform a like query in arel: users = User.arel_table User.where(users[:name].matches(“%#{user_name}%”)) PS: users = User.arel_table query_string = “%#{params[query]}%” param_matches_string = ->(param){ users[param].matches(query_string) } User.where(param_matches_string.(:name)\ .or(param_matches_string.(:description)))
accepts_nested_attributes_for with find_or_create?
When you define a hook for autosave associations, the normal code path is skipped and your method is called instead. Thus, you can do this: class Post < ActiveRecord::Base belongs_to :author, :autosave => true accepts_nested_attributes_for :author # If you need to validate the associated record, you can add a method like this: # validate_associated_record_for_author def … Read more
Eager load polymorphic
My guess is that your models look like this: class User < ActiveRecord::Base has_many :reviews end class Review < ActiveRecord::Base belongs_to :user belongs_to :reviewable, polymorphic: true end class Shop < ActiveRecord::Base has_many :reviews, as: :reviewable end You are unable to do that query for several reasons. ActiveRecord is unable to build the join without additional … Read more
Case-insensitive search in Rails model
You’ll probably have to be more verbose here name = “Blue Jeans” model = Product.where(‘lower(name) = ?’, name.downcase).first model ||= Product.create(:name => name)
Is there a way to get a collection of all the Models in your Rails app?
The whole answer for Rails 3, 4 and 5 is: If cache_classes is off (by default it’s off in development, but on in production): Rails.application.eager_load! Then: ActiveRecord::Base.descendants This makes sure all models in your application, regardless of where they are, are loaded, and any gems you are using which provide models are also loaded. This … Read more