Fix scope_for_create to take only equality nodes

Related #39683.

If a scope has IN cluase, `scope_for_create` which is passed to
`assign_attributes` will include array values, and it will cause weird
behaviors.

That behavior was due to the `In` node was a subclass of the `Equality`
node (now the checking has migrated to `equality?` method).

i.e. It works unless IN queries, for example (BETWEEN):

```ruby
user = User.where(role: 0..1).find_or_initialize_by(name: "name")
```

I think that the `In` node was a subclass of the `Equality` node is
accidental, so the behavior is almost a bug to me.

This makes `scope_for_create` takes only equality nodes to fix the
issue.

Fixes #41295.

activerecord/lib/active_record/relation.rb

@@ -683,8 +683,7 @@ module ActiveRecord
     end
 
     def scope_for_create
-      hash = where_values_hash
-      hash.delete(klass.inheritance_column) if klass.finder_needs_type_condition?
+      hash = where_clause.to_h(klass.table_name, equality_only: true)
       create_with_value.each { |k, v| hash[k.to_s] = v } unless create_with_value.empty?
       hash
     end

activerecord/lib/active_record/relation/where_clause.rb

@@ -58,8 +58,8 @@ module ActiveRecord
         end
       end
 
-      def to_h(table_name = nil)
-        equalities(predicates).each_with_object({}) do |node, hash|
+      def to_h(table_name = nil, equality_only: false)
+        equalities(predicates, equality_only).each_with_object({}) do |node, hash|
           next if table_name&.!= node.left.relation.name
           name = node.left.name.to_s
           value = extract_node_value(node.right)
@@ -134,14 +134,14 @@ module ActiveRecord
           attr_node
         end
 
-        def equalities(predicates)
+        def equalities(predicates, equality_only)
           equalities = []
 
           predicates.each do |node|
-            if equality_node?(node)
+            if equality_only ? Arel::Nodes::Equality === node : equality_node?(node)
               equalities << node
             elsif node.is_a?(Arel::Nodes::And)
-              equalities.concat equalities(node.children)
+              equalities.concat equalities(node.children, equality_only)
             end
           end
 

activerecord/test/cases/scoping/relation_scoping_test.rb

@@ -212,6 +212,26 @@ class RelationScopingTest < ActiveRecord::TestCase
     assert_includes Post.find(1).comments, new_comment
   end
 
+  def test_scoped_create_with_where_with_array
+    new_comment = VerySpecialComment.where(label: [0, 1], post_id: 1).scoping do
+      VerySpecialComment.create body: "Wonderful world"
+    end
+
+    assert_equal 1, new_comment.post_id
+    assert_equal "default", new_comment.label
+    assert_includes Post.find(1).comments, new_comment
+  end
+
+  def test_scoped_create_with_where_with_range
+    new_comment = VerySpecialComment.where(label: 0..1, post_id: 1).scoping do
+      VerySpecialComment.create body: "Wonderful world"
+    end
+
+    assert_equal 1, new_comment.post_id
+    assert_equal "default", new_comment.label
+    assert_includes Post.find(1).comments, new_comment
+  end
+
   def test_scoped_create_with_create_with
     new_comment = VerySpecialComment.create_with(post_id: 1).scoping do
       VerySpecialComment.create body: "Wonderful world"