Merge pull request #13201 from marcandre/find_in_batch_enumerator

`find_in_batches` now returns an `Enumerator`

Conflicts:
	activerecord/CHANGELOG.md
	activerecord/lib/active_record/relation/batches.rb

1 files changed, 9 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/relation/batches.rb b/activerecord/lib/active_record/relation/batches.rb
index e98b4712f5..dfcfef2ad2 100644
--- a/activerecord/lib/active_record/relation/batches.rb
+++ b/activerecord/lib/active_record/relation/batches.rb
@@ -64,6 +64,14 @@ module ActiveRecord
     #     group.each { |person| person.party_all_night! }
     #   end
     #
+    # If you do not provide a block to #find_in_batches, it will return an Enumerator
+    # for chaining with other methods:
+    #
+    #   Person.find_in_batches.with_index do |group, batch|
+    #     puts "Processing group ##{batch}"
+    #     group.each(&:recover_from_last_night!)
+    #   end
+    #
     # To be yielded each record one by one, use #find_each instead.
     #
     # ==== Options
@@ -88,6 +96,7 @@ module ActiveRecord
     # the batch sizes.
     def find_in_batches(options = {})
       options.assert_valid_keys(:start, :batch_size)
+      return to_enum(:find_in_batches, options) unless block_given?
 
       relation = self