diff options
Diffstat (limited to 'activerecord/lib')
| -rw-r--r-- | activerecord/lib/active_record/relation/query_methods.rb | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb index a11b7a3864..670ba0987d 100644 --- a/activerecord/lib/active_record/relation/query_methods.rb +++ b/activerecord/lib/active_record/relation/query_methods.rb @@ -37,6 +37,35 @@ module ActiveRecord relation end + # Works in two unique ways. + # + # First: takes a block so it can be used just like Array#select. + # + # Model.scoped.select { |m| m.field == value } + # + # This will build an array of objects from the database for the scope, + # converting them into an array and iterating through them using Array#select. + # + # Second: Modifies the SELECT statement for the query so that only certain + # fields are retrieved: + # + # >> Model.select(:field) + # => [#<Model field:value>] + # + # Although in the above example it looks as though this method returns an + # array, it actually returns a relation object and can have other query + # methods appended to it, such as the other methods in ActiveRecord::QueryMethods. + # + # This method will also take multiple parameters: + # + # >> Model.select(:field, :other_field, :and_one_more) + # => [#<Model field: "value", other_field: "value", and_one_more: "value">] + # + # Any attributes that do not have fields retrieved by a select + # will return `nil` when the getter method for that attribute is used: + # + # >> Model.select(:field).first.other_field + # => nil def select(value = Proc.new) if block_given? to_a.select {|*block_args| value.call(*block_args) } |