Model.select(:rating) The result of this is a collection of Model objects. Not plain ratings. And from uniq‘s point of view, they are completely different. You can use this: Model.select(:rating).map(&:rating).uniq or this (most efficient): Model.uniq.pluck(:rating) Rails 5+ Model.distinct.pluck(:rating) Update Apparently, as of rails 5.0.0.1, it works only on “top level” queries, like above. Doesn’t work on … Read more
The ability to chain or clause along with where clause in ActiveRecord query will be available in Rails 5. See the related discussion and the pull request. So, you will be able to do the following things in Rails 5: To get a post with id 1 or 2: Post.where(‘id = 1’).or(Post.where(‘id = 2’)) Some … Read more
Thing.first(:order => “RANDOM()”) # For MySQL :order => “RAND()”, – thanx, @DanSingerman # Rails 3 Thing.order(“RANDOM()”).first or Thing.first(:offset => rand(Thing.count)) # Rails 3 Thing.offset(rand(Thing.count)).first Actually, in Rails 3 all examples will work. But using order RANDOM is quite slow for big tables but more sql-style UPD. You can use the following trick on an indexed … Read more
The column type is wrong. You should use Text instead of String. Therefore, your migration should be: def self.up add_column :users, :multi_wrong, :text end Then Rails will properly convert it into YAML for you (and perform proper serialization). Strings fields are limited in size and will only hold especially-small values.
Say you have these models: Car Engine Piston A car has_one :engine An engine belongs_to :car An engine has_many :pistons Piston belongs_to :engine A car has_many :pistons, through: :engine Piston has_one :car, through: :engine Essentially you are delegating a model relationship to another model, so instead of having to call car.engine.pistons, you can just do … Read more
There is a known issue with Rails 3.1.1 that breaks this functionality. If you are having this problem first try upgrading, it’s been fixed in 3.1.2 You’re so close. The problem is you’re misusing the :source option. :source should points to the polymorphic belongs_to relationship. Then all you need to do is specify :source_type for … Read more
You would do Person.where(‘name=? OR lastname=?’, ‘John’, ‘Smith’) Right now, there isn’t any other OR support by the new AR3 syntax (that is without using some 3rd party gem).
Rails 5+ Support for left outer joins was introduced in Rails 5 so you can use an outer join instead of using counter_cache to do this. This way you’ll still keep the records that have 0 relationships: Company .left_joins(:jobs) .group(:id) .order(‘COUNT(jobs.id) DESC’) .limit(10) The SQL equivalent of the query is this (got by calling .to_sql … Read more
There are 5 options that could be considered as implementations of «Hash notation» (the last two are kinda hash-ish): With Ruby on Rails 5 you are able to do the following chaining using ActiveRecord::Relation#or method: Person.where(name: ‘Neil’).or(Person.where(age: 27)) Use where_values together with reduce. The unscoped method is necessary only for Rails 4.1+ to ensure default_scope … Read more
ActiveSupport::Inflector.transliterate (requires Rails 2.2.1+ and Ruby 1.9 or 1.8.7) example: >> ActiveSupport::Inflector.transliterate(“àáâãäå”).to_s => “aaaaaa”