Class: EagerGroup::Preloader

Inherits:
Object
  • Object
show all
Defined in:
lib/eager_group/preloader.rb,
lib/eager_group/preloader/has_many.rb,
lib/eager_group/preloader/many_to_many.rb,
lib/eager_group/preloader/aggregation_finder.rb,
lib/eager_group/preloader/has_many_through_many.rb,
lib/eager_group/preloader/has_many_through_belongs_to.rb

Defined Under Namespace

Classes: AggregationFinder, HasMany, HasManyThroughBelongsTo, HasManyThroughMany, ManyToMany

Instance Method Summary collapse

Constructor Details

#initialize(klass, records, eager_group_values) ⇒ Preloader

Returns a new instance of Preloader.



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# File 'lib/eager_group/preloader.rb', line 11

def initialize(klass, records, eager_group_values)
  @klass = klass
  @records = Array.wrap(records).compact.uniq
  eager_group_definitions = @klass.eager_group_definitions
  @eager_group_values = eager_group_values.all? { |value| eager_group_definitions.key?(value) } ? eager_group_values : [eager_group_values]
end

Instance Method Details

#find_aggregate_values_per_definition!(definition_key, arguments) ⇒ Object 



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# File 'lib/eager_group/preloader.rb', line 38

def find_aggregate_values_per_definition!(definition_key, arguments)
  unless definition = @klass.eager_group_definitions[definition_key]
    return
  end

  reflection = @klass.reflect_on_association(definition.association)
  return if reflection.blank?

  aggregation_finder_class = if reflection.is_a?(ActiveRecord::Reflection::HasAndBelongsToManyReflection)
    ManyToMany
  elsif reflection.through_reflection
    if reflection.through_reflection.is_a?(ActiveRecord::Reflection::BelongsToReflection)
      HasManyThroughBelongsTo
    else
      HasManyThroughMany
    end
  else
    HasMany
  end

  aggregation_finder = aggregation_finder_class.new(@klass, definition, arguments, @records)
  aggregate_hash = aggregation_finder.aggregate_hash

  if definition.need_load_object
    aggregate_objects = reflection.klass.find(aggregate_hash.values).each_with_object({}) { |o, h| h[o.id] = o }
    aggregate_hash.keys.each { |key| aggregate_hash[key] = aggregate_objects[aggregate_hash[key]] }
  end

  @records.each do |record|
    id = record.send(aggregation_finder.group_by_key)
    record.send("#{definition_key}=", aggregate_hash[id] || definition.default_value)
  end
end

#run ⇒ Object

Preload aggregate functions



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# File 'lib/eager_group/preloader.rb', line 19

def run
  @eager_group_values.each do |eager_group_value|
    definition_key, arguments =
      eager_group_value.is_a?(Array) ? [eager_group_value.shift, eager_group_value] : [eager_group_value, nil]

    if definition_key.is_a?(Hash)
      association_name, definition_key = *definition_key.first
      @records = @records.flat_map { |record| record.send(association_name) }
      next if @records.empty?

      @klass = @records.first.class
    end

    Array.wrap(definition_key).each do |key|
      find_aggregate_values_per_definition!(key, arguments)
    end
  end
end