Use a type object for type casting behavior on SQLite3

activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb

@@ -50,6 +50,16 @@ module ActiveRecord
       end
     end
 
+    class SQLite3String < Type::String # :nodoc:
+      def type_cast_for_database(value)
+        if value.is_a?(::String) && value.encoding == Encoding::ASCII_8BIT
+          value.encode(Encoding::UTF_8)
+        else
+          super
+        end
+      end
+    end
+
     # The SQLite3 adapter works SQLite 3.6.16 or newer
     # with the sqlite3-ruby drivers (available as gem from https://rubygems.org/gems/sqlite3).
     #
@@ -220,13 +230,23 @@ module ActiveRecord
       # QUOTING ==================================================
 
       def _quote(value) # :nodoc:
-        if value.is_a?(Type::Binary::Data)
+        case value
+        when Type::Binary::Data
           "x'#{value.hex}'"
         else
           super
         end
       end
 
+      def _type_cast(value) # :nodoc:
+        case value
+        when BigDecimal
+          value.to_f
+        else
+          super
+        end
+      end
+
       def quote_string(s) #:nodoc:
         @connection.class.quote(s)
       end
@@ -249,19 +269,6 @@ module ActiveRecord
         end
       end
 
-      def type_cast(value, column) # :nodoc:
-        return value.to_f if BigDecimal === value
-        return super unless String === value
-        return super unless column && value
-
-        value = super
-        if column.type == :string && value.encoding == Encoding::ASCII_8BIT
-          logger.error "Binary data inserted for `string` type on column `#{column.name}`" if logger
-          value = value.encode Encoding::UTF_8
-        end
-        value
-      end
-
       # DATABASE STATEMENTS ======================================
 
       def explain(arel, binds = [])
@@ -503,6 +510,7 @@ module ActiveRecord
         def initialize_type_map(m)
           super
           m.register_type(/binary/i, SQLite3Binary.new)
+          register_class_with_limit m, %r(char)i, SQLite3String
         end
 
         def select(sql, name = nil, binds = []) #:nodoc:

activerecord/test/cases/adapters/sqlite3/quoting_test.rb

@@ -103,6 +103,13 @@ module ActiveRecord
           }.new
           assert_raise(TypeError) { @conn.type_cast(quoted_id_obj, nil) }
         end
+
+        def test_quoting_binary_strings
+          value = "hello".encode('ascii-8bit')
+          column = Column.new(nil, 1, SQLite3String.new)
+
+          assert_equal "'hello'", @conn.quote(value, column)
+        end
       end
     end
   end