Extract data_source_sql to refactor data source statements

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

@@ -31,6 +31,8 @@ def table_alias_for(table_name)
       # Returns the relation names useable to back Active Record models.
       # For most adapters this means all #tables and #views.
       def data_sources
+        select_values(data_source_sql, "SCHEMA")
+      rescue NotImplementedError
         tables | views
       end
 
@@ -39,32 +41,38 @@ def data_sources
       #   data_source_exists?(:ebooks)
       #
       def data_source_exists?(name)
+        select_values(data_source_sql(name), "SCHEMA").any? if name.present?
+      rescue NotImplementedError
         data_sources.include?(name.to_s)
       end
 
       # Returns an array of table names defined in the database.
       def tables
-        raise NotImplementedError, "#tables is not implemented"
+        select_values(data_source_sql(type: "BASE TABLE"), "SCHEMA")
       end
 
       # Checks to see if the table +table_name+ exists on the database.
       #
       #   table_exists?(:developers)
       #
       def table_exists?(table_name)
+        select_values(data_source_sql(table_name, type: "BASE TABLE"), "SCHEMA").any? if table_name.present?
+      rescue NotImplementedError
         tables.include?(table_name.to_s)
       end
 
       # Returns an array of view names defined in the database.
       def views
-        raise NotImplementedError, "#views is not implemented"
+        select_values(data_source_sql(type: "VIEW"), "SCHEMA")
       end
 
       # Checks to see if the view +view_name+ exists on the database.
       #
       #   view_exists?(:ebooks)
       #
       def view_exists?(view_name)
+        select_values(data_source_sql(view_name, type: "VIEW"), "SCHEMA").any? if view_name.present?
+      rescue NotImplementedError
         views.include?(view_name.to_s)
       end
 
@@ -1306,6 +1314,14 @@ def extract_new_default_value(default_or_changes)
         def can_remove_index_by_name?(options)
           options.is_a?(Hash) && options.key?(:name) && options.except(:name, :algorithm).empty?
         end
+
+        def data_source_sql(name = nil, type: nil)
+          raise NotImplementedError
+        end
+
+        def quoted_scope(name = nil, type: nil)
+          raise NotImplementedError
+        end
     end
   end
 end

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -6,6 +6,7 @@
 require "active_record/connection_adapters/mysql/schema_creation"
 require "active_record/connection_adapters/mysql/schema_definitions"
 require "active_record/connection_adapters/mysql/schema_dumper"
+require "active_record/connection_adapters/mysql/schema_statements"
 require "active_record/connection_adapters/mysql/type_metadata"
 
 require "active_support/core_ext/string/strip"
@@ -15,6 +16,7 @@ module ConnectionAdapters
     class AbstractMysqlAdapter < AbstractAdapter
       include MySQL::Quoting
       include MySQL::ColumnDumper
+      include MySQL::SchemaStatements
 
       def update_table_definition(table_name, base) # :nodoc:
         MySQL::Table.new(table_name, base)
@@ -314,57 +316,6 @@ def collation
         show_variable "collation_database"
       end
 
-      def tables # :nodoc:
-        sql = "SELECT table_name FROM information_schema.tables WHERE table_type = 'BASE TABLE'"
-        sql << " AND table_schema = #{quote(@config[:database])}"
-
-        select_values(sql, "SCHEMA")
-      end
-
-      def views # :nodoc:
-        select_values("SHOW FULL TABLES WHERE table_type = 'VIEW'", "SCHEMA")
-      end
-
-      def data_sources # :nodoc:
-        sql = "SELECT table_name FROM information_schema.tables "
-        sql << "WHERE table_schema = #{quote(@config[:database])}"
-
-        select_values(sql, "SCHEMA")
-      end
-
-      def table_exists?(table_name) # :nodoc:
-        return false unless table_name.present?
-
-        schema, name = extract_schema_qualified_name(table_name)
-
-        sql = "SELECT table_name FROM information_schema.tables WHERE table_type = 'BASE TABLE'"
-        sql << " AND table_schema = #{quote(schema)} AND table_name = #{quote(name)}"
-
-        select_values(sql, "SCHEMA").any?
-      end
-
-      def data_source_exists?(table_name) # :nodoc:
-        return false unless table_name.present?
-
-        schema, name = extract_schema_qualified_name(table_name)
-
-        sql = "SELECT table_name FROM information_schema.tables "
-        sql << "WHERE table_schema = #{quote(schema)} AND table_name = #{quote(name)}"
-
-        select_values(sql, "SCHEMA").any?
-      end
-
-      def view_exists?(view_name) # :nodoc:
-        return false unless view_name.present?
-
-        schema, name = extract_schema_qualified_name(view_name)
-
-        sql = "SELECT table_name FROM information_schema.tables WHERE table_type = 'VIEW'"
-        sql << " AND table_schema = #{quote(schema)} AND table_name = #{quote(name)}"
-
-        select_values(sql, "SCHEMA").any?
-      end
-
       def truncate(table_name, name = nil)
         execute "TRUNCATE TABLE #{quote_table_name(table_name)}", name
       end
@@ -410,13 +361,13 @@ def new_column_from_field(table_name, field) # :nodoc:
       end
 
       def table_comment(table_name) # :nodoc:
-        schema, name = extract_schema_qualified_name(table_name)
+        scope = quoted_scope(table_name)
 
         select_value(<<-SQL.strip_heredoc, "SCHEMA")
           SELECT table_comment
           FROM information_schema.tables
-          WHERE table_schema = #{quote(schema)}
-            AND table_name = #{quote(name)}
+          WHERE table_schema = #{scope[:schema]}
+            AND table_name = #{scope[:name]}
         SQL
       end
 
@@ -516,7 +467,7 @@ def add_sql_comment!(sql, comment) # :nodoc:
       def foreign_keys(table_name)
         raise ArgumentError unless table_name.present?
 
-        schema, name = extract_schema_qualified_name(table_name)
+        scope = quoted_scope(table_name)
 
         fk_info = select_all(<<-SQL.strip_heredoc, "SCHEMA")
           SELECT fk.referenced_table_name AS 'to_table',
@@ -529,9 +480,9 @@ def foreign_keys(table_name)
           JOIN information_schema.referential_constraints rc
           USING (constraint_schema, constraint_name)
           WHERE fk.referenced_column_name IS NOT NULL
-            AND fk.table_schema = #{quote(schema)}
-            AND fk.table_name = #{quote(name)}
-            AND rc.table_name = #{quote(name)}
+            AND fk.table_schema = #{scope[:schema]}
+            AND fk.table_name = #{scope[:name]}
+            AND rc.table_name = #{scope[:name]}
         SQL
 
         fk_info.map do |row|
@@ -603,14 +554,14 @@ def show_variable(name)
       def primary_keys(table_name) # :nodoc:
         raise ArgumentError unless table_name.present?
 
-        schema, name = extract_schema_qualified_name(table_name)
+        scope = quoted_scope(table_name)
 
         select_values(<<-SQL.strip_heredoc, "SCHEMA")
           SELECT column_name
           FROM information_schema.key_column_usage
           WHERE constraint_name = 'PRIMARY'
-            AND table_schema = #{quote(schema)}
-            AND table_name = #{quote(name)}
+            AND table_schema = #{scope[:schema]}
+            AND table_name = #{scope[:name]}
           ORDER BY ordinal_position
         SQL
       end
@@ -948,12 +899,6 @@ def mismatched_foreign_key(message)
           )
         end
 
-        def extract_schema_qualified_name(string) # :nodoc:
-          schema, name = string.to_s.scan(/[^`.\s]+|`[^`]*`/)
-          schema, name = @config[:database], schema unless name
-          [schema, name]
-        end
-
         def integer_to_sql(limit) # :nodoc:
           case limit
           when 1; "tinyint"

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

@@ -0,0 +1,33 @@
+module ActiveRecord
+  module ConnectionAdapters
+    module MySQL
+      module SchemaStatements # :nodoc:
+        private
+          def data_source_sql(name = nil, type: nil)
+            scope = quoted_scope(name, type: type)
+
+            sql = "SELECT table_name FROM information_schema.tables"
+            sql << " WHERE table_schema = #{scope[:schema]}"
+            sql << " AND table_name = #{scope[:name]}" if scope[:name]
+            sql << " AND table_type = #{scope[:type]}" if scope[:type]
+            sql
+          end
+
+          def quoted_scope(name = nil, type: nil)
+            schema, name = extract_schema_qualified_name(name)
+            scope = {}
+            scope[:schema] = schema ? quote(schema) : "database()"
+            scope[:name] = quote(name) if name
+            scope[:type] = quote(type) if type
+            scope
+          end
+
+          def extract_schema_qualified_name(string)
+            schema, name = string.to_s.scan(/[^`.\s]+|`[^`]*`/)
+            schema, name = nil, schema unless name
+            [schema, name]
+          end
+      end
+    end
+  end
+end