Class: EagerGroup::Preloader

Inherits:
Object
  • Object
show all
Defined in:
lib/eager_group/preloader.rb

Instance Method Summary collapse

Constructor Details

#initialize(klass, records, eager_group_values) ⇒ Preloader

Returns a new instance of Preloader.



3
4
5
6
7
 
# File 'lib/eager_group/preloader.rb', line 3

def initialize(klass, records, eager_group_values)
  @klass = klass
  @records = Array.wrap(records).compact.uniq
  @eager_group_values = eager_group_values
end

Instance Method Details

#run ⇒ Object

Preload aggregate functions



10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
 
# File 'lib/eager_group/preloader.rb', line 10

def run
  primary_key = @klass.primary_key
  record_ids = @records.map { |record| record.send primary_key }
  @eager_group_values.each do |eager_group_value|
    definition = @klass.eager_group_definations[eager_group_value]
    if definition
      reflect = @klass.reflect_on_association(definition.association)
      association_class = reflect.class_name.constantize
      association_class = association_class.instance_exec(&definition.scope) if definition.scope
      aggregate_hash = association_class.where(reflect.foreign_key => record_ids)
                                        .group(reflect.foreign_key)
                                        .send(definition.aggregate_function, definition.column_name)
      @records.each do |record|
        id = record.send primary_key
        record.send "#{eager_group_value}=", aggregate_hash[id]
      end
    end
  end
end