diff options
Diffstat (limited to 'activerecord/lib/active_record/relation')
-rw-r--r-- | activerecord/lib/active_record/relation/calculations.rb | 55 | ||||
-rw-r--r-- | activerecord/lib/active_record/relation/merger.rb | 3 | ||||
-rw-r--r-- | activerecord/lib/active_record/relation/query_methods.rb | 34 |
3 files changed, 70 insertions, 22 deletions
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb index 3ce9995031..31d99f0192 100644 --- a/activerecord/lib/active_record/relation/calculations.rb +++ b/activerecord/lib/active_record/relation/calculations.rb @@ -108,34 +108,57 @@ module ActiveRecord 0 end - # This method is designed to perform select by a single column as direct SQL query - # Returns <tt>Array</tt> with values of the specified column name - # The values has same data type as column. + # Use <tt>pluck</tt> as a shortcut to select a single attribute without + # loading a bunch of records just to grab one attribute you want. + # + # Person.pluck(:name) + # + # instead of + # + # Person.all.map(&:name) + # + # Pluck returns an <tt>Array</tt> of attribute values type-casted to match + # the plucked column name, if it can be deduced. Plucking a SQL fragment + # returns String values by default. # # Examples: # - # Person.pluck(:id) # SELECT people.id FROM people - # Person.uniq.pluck(:role) # SELECT DISTINCT role FROM people - # Person.where(:age => 21).limit(5).pluck(:id) # SELECT people.id FROM people WHERE people.age = 21 LIMIT 5 + # Person.pluck(:id) + # # SELECT people.id FROM people + # # => [1, 2, 3] + # + # Person.uniq.pluck(:role) + # # SELECT DISTINCT role FROM people + # # => ['admin', 'member', 'guest'] + # + # Person.where(:age => 21).limit(5).pluck(:id) + # # SELECT people.id FROM people WHERE people.age = 21 LIMIT 5 + # # => [2, 3] + # + # Person.pluck('DATEDIFF(updated_at, created_at)') + # # SELECT DATEDIFF(updated_at, created_at) FROM people + # # => ['0', '27761', '173'] # def pluck(column_name) - key = column_name.to_s.split('.', 2).last - if column_name.is_a?(Symbol) && column_names.include?(column_name.to_s) column_name = "#{table_name}.#{column_name}" end result = klass.connection.select_all(select(column_name).arel, nil, bind_values) - types = result.column_types.merge klass.column_types - column = types[key] + + key = result.columns.first + column = klass.column_types.fetch(key) { + result.column_types.fetch(key) { + Class.new { def type_cast(v); v; end }.new + } + } result.map do |attributes| - value = klass.initialize_attributes(attributes)[key] - if column - column.type_cast value - else - value - end + raise ArgumentError, "Pluck expects to select just one attribute: #{attributes.inspect}" unless attributes.one? + + value = klass.initialize_attributes(attributes).values.first + + column.type_cast(value) end end diff --git a/activerecord/lib/active_record/relation/merger.rb b/activerecord/lib/active_record/relation/merger.rb index 3f880ce5e9..36f98c6480 100644 --- a/activerecord/lib/active_record/relation/merger.rb +++ b/activerecord/lib/active_record/relation/merger.rb @@ -43,7 +43,7 @@ module ActiveRecord def normal_values Relation::SINGLE_VALUE_METHODS + Relation::MULTI_VALUE_METHODS - - [:where, :order, :bind, :reverse_order, :lock, :create_with, :reordering] + [:where, :order, :bind, :reverse_order, :lock, :create_with, :reordering, :from] end def merge @@ -76,6 +76,7 @@ module ActiveRecord end def merge_single_values + relation.from_value = values[:from] unless relation.from_value relation.lock_value = values[:lock] unless relation.lock_value relation.reverse_order_value = values[:reverse_order] diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb index 29536b16c4..19fe8155d9 100644 --- a/activerecord/lib/active_record/relation/query_methods.rb +++ b/activerecord/lib/active_record/relation/query_methods.rb @@ -300,12 +300,25 @@ module ActiveRecord self end - def from(value) - spawn.from!(value) + # Specifies table from which the records will be fetched. For example: + # + # Topic.select('title').from('posts') + # #=> SELECT title FROM posts + # + # Can accept other relation objects. For example: + # + # Topic.select('title').from(Topics.approved) + # # => SELECT title FROM (SELECT * FROM topics WHERE approved = 't') subquery + # + # Topics.select('a.title').from(Topics.approved, :a) + # # => SELECT a.title FROM (SELECT * FROM topics WHERE approved = 't') a + # + def from(value, subquery_name = nil) + spawn.from!(value, subquery_name) end - def from!(value) - self.from_value = value + def from!(value, subquery_name = nil) + self.from_value = [value, subquery_name] self end @@ -415,7 +428,7 @@ module ActiveRecord build_select(arel, select_values.uniq) arel.distinct(uniq_value) - arel.from(from_value) if from_value + arel.from(build_from) if from_value arel.lock(lock_value) if lock_value arel @@ -464,6 +477,17 @@ module ActiveRecord end end + def build_from + opts, name = from_value + case opts + when Relation + name ||= 'subquery' + opts.arel.as(name.to_s) + else + opts + end + end + def build_joins(manager, joins) buckets = joins.group_by do |join| case join |