Allow to pass array values to .in_order_of

Passing arrays allows to group records and order those groups with another query:

```rb
Posts
  .in_order_of(:state, [[:published, :canceled], :archived])
  .order(created_at: :desc)
```

activerecord/CHANGELOG.md

@@ -1,3 +1,21 @@
+*   Allow to pass array values to `in_order_of`
+
+    Passing arrays allows to group records and order those groups with another query:
+
+    ```rb
+    Posts
+      .in_order_of(:state, [[:published, :canceled], :archived])
+      .order(created_at: :desc)
+    # =>
+    # SELECT "posts".* FROM "posts" WHERE "posts"."state" IN (1, 2, 3)
+    # ORDER BY CASE
+    #   WHEN "posts"."state" IN (1, 2) THEN 1
+    #   WHEN "posts"."state" = 3 THEN 2
+    #  END ASC, "posts"."created_at" DESC
+    ```
+
+    *Markus Doits*
+
 *   Make Float distinguish between `float4` and `float8` in PostgreSQL.
 
     Fixes #52742

activerecord/lib/active_record/relation/query_methods.rb

@@ -719,17 +719,25 @@ def in_order_of(column, values, filter: true)
       references = column_references([column])
       self.references_values |= references unless references.empty?
 
-      values = values.map { |value| model.type_caster.type_cast_for_database(column, value) }
+      values = values.map do |value|
+        if value.is_a?(Array)
+          value.map do |current_value|
+            model.type_caster.type_cast_for_database(column, current_value)
+          end
+        else
+          model.type_caster.type_cast_for_database(column, value)
+        end
+      end
       arel_column = column.is_a?(Arel::Nodes::SqlLiteral) ? column : order_column(column.to_s)
 
       scope = spawn.order!(build_case_for_value_position(arel_column, values, filter: filter))
 
       if filter
         where_clause =
           if values.include?(nil)
-            arel_column.in(values.compact).or(arel_column.eq(nil))
+            arel_column.in(values.compact.flatten(1)).or(arel_column.eq(nil))
           else
-            arel_column.in(values)
+            arel_column.in(values.flatten(1))
           end
 
         scope = scope.where!(where_clause)
@@ -2133,7 +2141,11 @@ def order_column(field)
       def build_case_for_value_position(column, values, filter: true)
         node = Arel::Nodes::Case.new
         values.each.with_index(1) do |value, order|
-          node.when(column.eq(value)).then(order)
+          if value.is_a?(Array)
+            node.when(column.in(value)).then(order)
+          else
+            node.when(column.eq(value)).then(order)
+          end
         end
 
         node = node.else(values.length + 1) unless filter

activerecord/test/cases/relation/field_ordered_values_test.rb

@@ -117,4 +117,11 @@ def test_in_order_of_with_filter_false
     assert_equal(order, posts.limit(3).map(&:id))
     assert_equal(11, posts.count)
   end
+
+  def test_in_order_of_with_array_values
+    order = [3, [5, 2], [4, 7], 1]
+    posts = Post.in_order_of(:id, order).order(id: :asc)
+
+    assert_equal([3, 2, 5, 4, 7, 1], posts.map(&:id))
+  end
 end