Don't passing a nil value to `case_sensitive_comparison`

A `value` is only used for checking `value.nil?`. It is unnecessary if
immediately return when `value.nil?`.

3 files changed, 9 insertions, 13 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index 0b8bacff4e..0c99c00e78 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -434,11 +434,7 @@ module ActiveRecord
       end
 
       def case_sensitive_comparison(table, attribute, column, value)
-        if value.nil?
-          table[attribute].eq(value)
-        else
-          table[attribute].eq(Arel::Nodes::BindParam.new)
-        end
+        table[attribute].eq(Arel::Nodes::BindParam.new)
       end
 
       def case_insensitive_comparison(table, attribute, column, value)
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 5e9705e02f..85321e825a 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -614,7 +614,7 @@ module ActiveRecord
       end
 
       def case_sensitive_comparison(table, attribute, column, value)
-        if !value.nil? && column.collation && !column.case_sensitive?
+        if column.collation && !column.case_sensitive?
           table[attribute].eq(Arel::Nodes::Bin.new(Arel::Nodes::BindParam.new))
         else
           super
diff --git a/activerecord/lib/active_record/validations/uniqueness.rb b/activerecord/lib/active_record/validations/uniqueness.rb
index 608d072e48..58273509be 100644
--- a/activerecord/lib/active_record/validations/uniqueness.rb
+++ b/activerecord/lib/active_record/validations/uniqueness.rb
@@ -55,6 +55,10 @@ module ActiveRecord
           value = value.attributes[reflection.klass.primary_key] unless value.nil?
         end
 
+        if value.nil?
+          return klass.unscoped.where!(attribute => value)
+        end
+
         # the attribute may be an aliased attribute
         if klass.attribute_alias?(attribute)
           attribute = klass.attribute_alias(attribute)
@@ -66,18 +70,14 @@ module ActiveRecord
         column = klass.columns_hash[attribute_name]
         cast_type = klass.type_for_attribute(attribute_name)
 
-        comparison = if !options[:case_sensitive] && !value.nil?
+        comparison = if !options[:case_sensitive]
           # will use SQL LOWER function before comparison, unless it detects a case insensitive collation
           klass.connection.case_insensitive_comparison(table, attribute, column, value)
         else
           klass.connection.case_sensitive_comparison(table, attribute, column, value)
         end
-        if value.nil?
-          klass.unscoped.where(comparison)
-        else
-          bind = Relation::QueryAttribute.new(attribute_name, value, cast_type)
-          klass.unscoped.where(comparison, bind)
-        end
+        bind = Relation::QueryAttribute.new(attribute_name, value, cast_type)
+        klass.unscoped.where!(comparison, bind)
       end
 
       def scope_relation(record, relation)