Module: Switchman::ActiveRecord::Preloader::Association

Defined in:
lib/switchman/active_record/association.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(klass) ⇒ Object 



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# File 'lib/switchman/active_record/association.rb', line 92

def self.included(klass)
  klass.send(:remove_method, :associated_records_by_owner)
  klass.send(:remove_method, :owners_by_key)
  klass.send(:remove_method, :scope)
end

Instance Method Details

#associated_records_by_owner(preloader = nil) ⇒ Object 



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# File 'lib/switchman/active_record/association.rb', line 98

def associated_records_by_owner(preloader = nil)
  owners_map = owners_by_key

  if klass.nil? || owners_map.empty?
    records = []
  else
    # determine the shard to search for each owner
    if reflection.macro == :belongs_to
      # for belongs_to, it's the shard of the foreign_key
      partition_proc = ->(owner) do
        if owner.class.sharded_column?(owner_key_name)
          Shard.shard_for(owner, owner[owner_key_name])
        else
          Shard.current
        end
      end
    elsif !reflection.options[:multishard]
      # for non-multishard associations, it's *just* the owner's shard
      partition_proc = ->(owner) { owner.shard }
    else
      # for multishard associations, it's the owner object itself
      # (all associated shards)

      # this is the default behavior of partition_by_shard, so just set it to nil
      # to avoid the proc call
      # partition_proc = ->(owner) { owner }
      partitition_proc = nil
    end

    records = Shard.partition_by_shard(owners, partition_proc) do |partitioned_owners|
      # Some databases impose a limit on the number of ids in a list (in Oracle it's 1000)
      # Make several smaller queries if necessary or make one query if the adapter supports it
      sliced_owners = partitioned_owners.each_slice(model.connection.in_clause_length || partitioned_owners.size)
      sliced_owners.map do |slice|
        relative_owner_keys = slice.map do |owner|
          key = owner[owner_key_name]
          if key && owner.class.sharded_column?(owner_key_name)
            key = Shard.relative_id_for(key, owner.shard, Shard.current(owner.class.shard_category))
          end
          key && key.to_s
        end
        relative_owner_keys.compact!
        relative_owner_keys.uniq!
        records_for(relative_owner_keys)
      end
    end
    records.flatten!
  end

  if ::Rails.version >= '4.1'
    @preloaded_records = records
  end

  # Each record may have multiple owners, and vice-versa
  records_by_owner = owners.each_with_object({}) do |owner,h|
    h[owner] = []
  end
  records.each do |record|
    owner_key = record[association_key_name]
    owner_key = Shard.global_id_for(owner_key, record.shard) if owner_key && record.class.sharded_column?(association_key_name)

    owners_map[owner_key.to_s].each do |owner|
      records_by_owner[owner] << record
    end
  end
  records_by_owner
end

#owners_by_key ⇒ Object 



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# File 'lib/switchman/active_record/association.rb', line 166

def owners_by_key
  @owners_by_key ||= owners.group_by do |owner|
    key = owner[owner_key_name]
    key = Shard.global_id_for(key, owner.shard) if key && owner.class.sharded_column?(owner_key_name)
    key && key.to_s
  end
end

#scope ⇒ Object 



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# File 'lib/switchman/active_record/association.rb', line 174

def scope
  build_scope
end