Move the collation handling code from the MySQL adapter to common classes

Some databases like MySQL allow defining collation charset for specific
columns.

activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb

@@ -70,6 +70,7 @@ def column_options(o)
             column_options[:after] = o.after
             column_options[:auto_increment] = o.auto_increment
             column_options[:primary_key] = o.primary_key
+            column_options[:collation] = o.collation
             column_options
           end
 

activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb

@@ -15,7 +15,7 @@ class IndexDefinition < Struct.new(:table, :name, :unique, :columns, :lengths, :
     # are typically created by methods in TableDefinition, and added to the
     # +columns+ attribute of said TableDefinition object, in order to be used
     # for generating a number of table creation or table changing SQL statements.
-    class ColumnDefinition < Struct.new(:name, :type, :limit, :precision, :scale, :default, :null, :first, :after, :auto_increment, :primary_key, :sql_type) #:nodoc:
+    class ColumnDefinition < Struct.new(:name, :type, :limit, :precision, :scale, :default, :null, :first, :after, :auto_increment, :primary_key, :collation, :sql_type) #:nodoc:
 
       def primary_key?
         primary_key || type.to_sym == :primary_key
@@ -434,6 +434,7 @@ def new_column_definition(name, type, options) # :nodoc:
         column.after       = options[:after]
         column.auto_increment = options[:auto_increment]
         column.primary_key = type == :primary_key || options[:primary_key]
+        column.collation   = options[:collation]
         column
       end
 

activerecord/lib/active_record/connection_adapters/abstract/schema_dumper.rb

@@ -35,12 +35,16 @@ def prepare_column_options(column)
         default = schema_default(column) if column.has_default?
         spec[:default]   = default unless default.nil?
 
+        if collation = schema_collation(column)
+          spec[:collation] = collation
+        end
+
         spec
       end
 
       # Lists the valid migration options
       def migration_keys
-        [:name, :limit, :precision, :scale, :default, :null]
+        [:name, :limit, :precision, :scale, :default, :null, :collation]
       end
 
       private
@@ -56,6 +60,10 @@ def schema_default(column)
           type.type_cast_for_schema(default)
         end
       end
+
+      def schema_collation(column)
+        column.collation.inspect if column.collation
+      end
     end
   end
 end

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -387,8 +387,8 @@ def type_map # :nodoc:
         end
       end
 
-      def new_column(name, default, sql_type_metadata = nil, null = true)
-        Column.new(name, default, sql_type_metadata, null)
+      def new_column(name, default, sql_type_metadata = nil, null = true, default_function = nil, collation = nil)
+        Column.new(name, default, sql_type_metadata, null, default_function, collation)
       end
 
       def lookup_cast_type(sql_type) # :nodoc:

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -14,7 +14,7 @@ def primary_key(name, type = :primary_key, **options)
       end
 
       class ColumnDefinition < ActiveRecord::ConnectionAdapters::ColumnDefinition
-        attr_accessor :charset, :collation
+        attr_accessor :charset
       end
 
       class TableDefinition < ActiveRecord::ConnectionAdapters::TableDefinition
@@ -28,7 +28,6 @@ def new_column_definition(name, type, options) # :nodoc:
             column.auto_increment = true
           end
           column.charset = options[:charset]
-          column.collation = options[:collation]
           column
         end
 
@@ -75,7 +74,6 @@ def visit_ChangeColumnDefinition(o)
         def column_options(o)
           column_options = super
           column_options[:charset] = o.charset
-          column_options[:collation] = o.collation
           column_options
         end
 
@@ -128,20 +126,20 @@ def prepare_column_options(column)
         spec = super
         spec.delete(:precision) if /time/ === column.sql_type && column.precision == 0
         spec.delete(:limit)     if :boolean === column.type
+        spec
+      end
+
+      def schema_collation(column)
         if column.collation && table_name = column.instance_variable_get(:@table_name)
           @collation_cache ||= {}
           @collation_cache[table_name] ||= select_one("SHOW TABLE STATUS LIKE '#{table_name}'")["Collation"]
-          spec[:collation] = column.collation.inspect if column.collation != @collation_cache[table_name]
+          column.collation.inspect if column.collation != @collation_cache[table_name]
         end
-        spec
-      end
-
-      def migration_keys
-        super + [:collation]
       end
+      private :schema_collation
 
       class Column < ConnectionAdapters::Column # :nodoc:
-        delegate :strict, :collation, :extra, to: :sql_type_metadata, allow_nil: true
+        delegate :strict, :extra, to: :sql_type_metadata, allow_nil: true
 
         def initialize(*)
           super
@@ -195,12 +193,11 @@ def assert_valid_default(default)
       end
 
       class MysqlTypeMetadata < DelegateClass(SqlTypeMetadata) # :nodoc:
-        attr_reader :collation, :extra, :strict
+        attr_reader :extra, :strict
 
-        def initialize(type_metadata, collation: "", extra: "", strict: false)
+        def initialize(type_metadata, extra: "", strict: false)
           super(type_metadata)
           @type_metadata = type_metadata
-          @collation = collation
           @extra = extra
           @strict = strict
         end
@@ -218,7 +215,7 @@ def hash
         protected
 
         def attributes_for_hash
-          [self.class, @type_metadata, collation, extra, strict]
+          [self.class, @type_metadata, extra, strict]
         end
       end
 
@@ -342,8 +339,8 @@ def each_hash(result) # :nodoc:
         raise NotImplementedError
       end
 
-      def new_column(field, default, sql_type_metadata = nil, null = true) # :nodoc:
-        Column.new(field, default, sql_type_metadata, null)
+      def new_column(field, default, sql_type_metadata = nil, null = true, default_function = nil, collation = nil) # :nodoc:
+        Column.new(field, default, sql_type_metadata, null, default_function, collation)
       end
 
       # Must return the MySQL error number from the exception, if the exception has an
@@ -566,8 +563,8 @@ def columns(table_name)#:nodoc:
           each_hash(result).map do |field|
             field_name = set_field_encoding(field[:Field])
             sql_type = field[:Type]
-            type_metadata = fetch_type_metadata(sql_type, field[:Collation], field[:Extra])
-            new_column(field_name, field[:Default], type_metadata, field[:Null] == "YES")
+            type_metadata = fetch_type_metadata(sql_type, field[:Extra])
+            new_column(field_name, field[:Default], type_metadata, field[:Null] == "YES", nil, field[:Collation])
           end
         end
       end
@@ -826,8 +823,8 @@ def extract_precision(sql_type)
         end
       end
 
-      def fetch_type_metadata(sql_type, collation = "", extra = "")
-        MysqlTypeMetadata.new(super(sql_type), collation: collation, extra: extra, strict: strict_mode?)
+      def fetch_type_metadata(sql_type, extra = "")
+        MysqlTypeMetadata.new(super(sql_type), extra: extra, strict: strict_mode?)
       end
 
       # MySQL is too stupid to create a temporary table for use subquery, so we have

activerecord/lib/active_record/connection_adapters/column.rb

@@ -12,7 +12,7 @@ module Format
         ISO_DATETIME = /\A(\d{4})-(\d\d)-(\d\d) (\d\d):(\d\d):(\d\d)(\.\d+)?\z/
       end
 
-      attr_reader :name, :null, :sql_type_metadata, :default, :default_function
+      attr_reader :name, :null, :sql_type_metadata, :default, :default_function, :collation
 
       delegate :precision, :scale, :limit, :type, :sql_type, to: :sql_type_metadata, allow_nil: true
 
@@ -22,12 +22,13 @@ module Format
       # +default+ is the type-casted default value, such as +new+ in <tt>sales_stage varchar(20) default 'new'</tt>.
       # +sql_type_metadata+ is various information about the type of the column
       # +null+ determines if this column allows +NULL+ values.
-      def initialize(name, default, sql_type_metadata = nil, null = true, default_function = nil)
+      def initialize(name, default, sql_type_metadata = nil, null = true, default_function = nil, collation = nil)
         @name = name
         @sql_type_metadata = sql_type_metadata
         @null = null
         @default = default
         @default_function = default_function
+        @collation = collation
         @table_name = nil
       end
 
@@ -60,7 +61,7 @@ def hash
       protected
 
       def attributes_for_hash
-        [self.class, name, default, sql_type_metadata, null, default_function]
+        [self.class, name, default, sql_type_metadata, null, default_function, collation]
       end
     end
 

activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb

@@ -169,8 +169,8 @@ def columns(table_name)
           end
         end
 
-        def new_column(name, default, sql_type_metadata = nil, null = true, default_function = nil) # :nodoc:
-          PostgreSQLColumn.new(name, default, sql_type_metadata, null, default_function)
+        def new_column(name, default, sql_type_metadata = nil, null = true, default_function = nil, collation = nil) # :nodoc:
+          PostgreSQLColumn.new(name, default, sql_type_metadata, null, default_function, collation)
         end
 
         # Returns the current database name.