Merge pull request #35350 from kamipo/deprecate_validate_uniqueness_mismatched_collation

Deprecate mismatched collation comparison for uniquness validator

6 files changed, 86 insertions, 12 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 42c0e6a190..ec412c2a9d 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,11 @@
+*   Deprecate mismatched collation comparison for uniquness validator.
+
+    Uniqueness validator will no longer enforce case sensitive comparison in Rails 6.1.
+    To continue case sensitive comparison on the case insensitive column,
+    pass `case_sensitive: true` option explicitly to the uniqueness validator.
+
+    *Ryuta Kamizono*
+
 *   Add `reselect` method. This is a short-hand for `unscope(:select).select(fields)`.
 
     Fixes #27340.
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index f205d77ddb..823efee301 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -506,7 +506,7 @@ module ActiveRecord
         @connection
       end
 
-      def default_uniqueness_comparison(attribute, value) # :nodoc:
+      def default_uniqueness_comparison(attribute, value, klass) # :nodoc:
         case_sensitive_comparison(attribute, value)
       end
 
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index 37506a97e2..96f902792e 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -453,6 +453,20 @@ module ActiveRecord
         SQL
       end
 
+      def default_uniqueness_comparison(attribute, value, klass) # :nodoc:
+        column = column_for_attribute(attribute)
+
+        if column.collation && !column.case_sensitive?
+          ActiveSupport::Deprecation.warn(<<~MSG.squish)
+            Uniqueness validator will no longer enforce case sensitive comparison in Rails 6.1.
+            To continue case sensitive comparison on the :#{attribute.name} attribute in #{klass} model,
+            pass `case_sensitive: true` option explicitly to the uniqueness validator.
+          MSG
+        end
+
+        super
+      end
+
       def case_sensitive_comparison(attribute, value) # :nodoc:
         column = column_for_attribute(attribute)
 
diff --git a/activerecord/lib/active_record/validations/uniqueness.rb b/activerecord/lib/active_record/validations/uniqueness.rb
index 88ae62c681..dc1be73a60 100644
--- a/activerecord/lib/active_record/validations/uniqueness.rb
+++ b/activerecord/lib/active_record/validations/uniqueness.rb
@@ -63,7 +63,7 @@ module ActiveRecord
           if bind.nil?
             attr.eq(bind)
           elsif !options.key?(:case_sensitive)
-            klass.connection.default_uniqueness_comparison(attr, bind)
+            klass.connection.default_uniqueness_comparison(attr, bind, klass)
           elsif options[:case_sensitive]
             klass.connection.case_sensitive_comparison(attr, bind)
           else
diff --git a/activerecord/test/cases/validations/uniqueness_validation_test.rb b/activerecord/test/cases/validations/uniqueness_validation_test.rb
index 8f6f47e5fb..301e552642 100644
--- a/activerecord/test/cases/validations/uniqueness_validation_test.rb
+++ b/activerecord/test/cases/validations/uniqueness_validation_test.rb
@@ -314,6 +314,51 @@ class UniquenessValidationTest < ActiveRecord::TestCase
     assert t3.save, "Should save t3 as unique"
   end
 
+  if current_adapter?(:Mysql2Adapter)
+    def test_deprecate_validate_uniqueness_mismatched_collation
+      Topic.validates_uniqueness_of(:author_email_address)
+
+      topic1 = Topic.new(author_email_address: "david@loudthinking.com")
+      topic2 = Topic.new(author_email_address: "David@loudthinking.com")
+
+      assert_equal 1, Topic.where(author_email_address: "david@loudthinking.com").count
+
+      assert_deprecated do
+        assert_not topic1.valid?
+        assert_not topic1.save
+        assert topic2.valid?
+        assert topic2.save
+      end
+
+      assert_equal 2, Topic.where(author_email_address: "david@loudthinking.com").count
+      assert_equal 2, Topic.where(author_email_address: "David@loudthinking.com").count
+    end
+  end
+
+  def test_validate_case_sensitive_uniqueness_by_default
+    Topic.validates_uniqueness_of(:author_email_address)
+
+    topic1 = Topic.new(author_email_address: "david@loudthinking.com")
+    topic2 = Topic.new(author_email_address: "David@loudthinking.com")
+
+    assert_equal 1, Topic.where(author_email_address: "david@loudthinking.com").count
+
+    ActiveSupport::Deprecation.silence do
+      assert_not topic1.valid?
+      assert_not topic1.save
+      assert topic2.valid?
+      assert topic2.save
+    end
+
+    if current_adapter?(:Mysql2Adapter)
+      assert_equal 2, Topic.where(author_email_address: "david@loudthinking.com").count
+      assert_equal 2, Topic.where(author_email_address: "David@loudthinking.com").count
+    else
+      assert_equal 1, Topic.where(author_email_address: "david@loudthinking.com").count
+      assert_equal 1, Topic.where(author_email_address: "David@loudthinking.com").count
+    end
+  end
+
   def test_validate_case_sensitive_uniqueness
     Topic.validates_uniqueness_of(:title, case_sensitive: true, allow_nil: true)
 
diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index 1dfea0f506..5d46bd47d9 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -8,6 +8,13 @@ ActiveRecord::Schema.define do
   #                                                                     #
   # ------------------------------------------------------------------- #
 
+  case_sensitive_options =
+    if current_adapter?(:Mysql2Adapter)
+      { collation: "utf8mb4_bin" }
+    else
+      {}
+    end
+
   create_table :accounts, force: true do |t|
     t.references :firm, index: false
     t.string  :firm_name
@@ -266,7 +273,7 @@ ActiveRecord::Schema.define do
   end
 
   create_table :dashboards, force: true, id: false do |t|
-    t.string :dashboard_id
+    t.string :dashboard_id, **case_sensitive_options
     t.string :name
   end
 
@@ -330,7 +337,7 @@ ActiveRecord::Schema.define do
   end
 
   create_table :essays, force: true do |t|
-    t.string :name
+    t.string :name, **case_sensitive_options
     t.string :writer_id
     t.string :writer_type
     t.string :category_id
@@ -338,7 +345,7 @@ ActiveRecord::Schema.define do
   end
 
   create_table :events, force: true do |t|
-    t.string :title, limit: 5
+    t.string :title, limit: 5, **case_sensitive_options
   end
 
   create_table :eyes, force: true do |t|
@@ -380,7 +387,7 @@ ActiveRecord::Schema.define do
   end
 
   create_table :guids, force: true do |t|
-    t.column :key, :string
+    t.column :key, :string, **case_sensitive_options
   end
 
   create_table :guitars, force: true do |t|
@@ -388,8 +395,8 @@ ActiveRecord::Schema.define do
   end
 
   create_table :inept_wizards, force: true do |t|
-    t.column :name, :string, null: false
-    t.column :city, :string, null: false
+    t.column :name, :string, null: false, **case_sensitive_options
+    t.column :city, :string, null: false, **case_sensitive_options
     t.column :type, :string
   end
 
@@ -876,8 +883,8 @@ ActiveRecord::Schema.define do
   end
 
   create_table :topics, force: true do |t|
-    t.string   :title, limit: 250
-    t.string   :author_name
+    t.string   :title, limit: 250, **case_sensitive_options
+    t.string   :author_name, **case_sensitive_options
     t.string   :author_email_address
     if subsecond_precision_supported?
       t.datetime :written_on, precision: 6
@@ -889,10 +896,10 @@ ActiveRecord::Schema.define do
     # use VARCHAR2(4000) instead of CLOB datatype as CLOB data type has many limitations in
     # Oracle SELECT WHERE clause which causes many unit test failures
     if current_adapter?(:OracleAdapter)
-      t.string   :content, limit: 4000
+      t.string   :content, limit: 4000, **case_sensitive_options
       t.string   :important, limit: 4000
     else
-      t.text     :content
+      t.text     :content, **case_sensitive_options
       t.text     :important
     end
     t.boolean  :approved, default: true