Module: CompositePrimaryKeys::ActiveRecord::Batches

Included in:
CompositeRelation
Defined in:
lib/composite_primary_keys/relation/batches.rb

Instance Method Summary collapse

Instance Method Details

#in_batches(of: 1000, start: nil, finish: nil, load: false, error_on_ignore: nil) ⇒ Object 



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# File 'lib/composite_primary_keys/relation/batches.rb', line 4

def in_batches(of: 1000, start: nil, finish: nil, load: false, error_on_ignore: nil)
  relation = self
  unless block_given?
    return BatchEnumerator.new(of: of, start: start, finish: finish, relation: self)
  end

  if arel.orders.present?
    act_on_ignored_order(error_on_ignore)
  end

  batch_limit = of
  if limit_value
    remaining   = limit_value
    batch_limit = remaining if remaining < batch_limit
  end

  relation = relation.reorder(batch_order).limit(batch_limit)
  relation = apply_limits(relation, start, finish)
  relation.skip_query_cache! # Retaining the results in the query cache would undermine the point of batching
  batch_relation = relation

  loop do
    if load
      records = batch_relation.records
      ids = records.map(&:id)
      # CPK
      # yielded_relation = self.where(primary_key => ids)
      yielded_relation = self.where(cpk_in_predicate(table, primary_keys, ids))
      yielded_relation.load_records(records)
    else
      # CPK
      # ids = batch_relation.pluck(primary_key)
      ids = batch_relation.pluck(*Array(primary_keys))
      # CPK
      # yielded_relation = self.where(primary_key => ids)
      yielded_relation = self.where(cpk_in_predicate(table, primary_keys, ids))
    end

    break if ids.empty?

    primary_key_offset = ids.last
    raise ArgumentError.new("Primary key not included in the custom select clause") unless primary_key_offset

    yield yielded_relation

    break if ids.length < batch_limit

    if limit_value
      remaining -= ids.length

      if remaining == 0
        # Saves a useless iteration when the limit is a multiple of the
        # batch size.
        break
      elsif remaining < batch_limit
        relation = relation.limit(remaining)
      end
    end

    # CPK
    # batch_relation = relation.where(arel_attribute(primary_key).gt(primary_key_offset))
    batch_relation = if composite?
      # CPK
      # Lexicographically select records
      #
      query = prefixes(primary_key.zip(primary_key_offset)).map do |kvs|
        and_clause = kvs.each_with_index.map do |(k, v), i|
          # Use > for the last key in the and clause
          # otherwise use =
          if i == kvs.length - 1
            table[k].gt(v)
          else
            table[k].eq(v)
          end
        end.reduce(:and)

        Arel::Nodes::Grouping.new(and_clause)
      end.reduce(:or)
      relation.where(query)
    else
      relation.where(arel_attribute(primary_key).gt(primary_key_offset))
    end
  end
end