Don't require an active connection for table and column quoting

Extracted from: rails#50793

Right now quoting table or column names requires a leased Adapter
instance, even though none of the implementations actually requires
an active connection.

The idea here is to move these methods to the class so that the quoting
can be done without leasing a connection or even needing the connection
to ever have been established.

I also checked `activerecord-sqlserver-adapter` and `oracle-enhanced`
gems, and neither need an active connection.

Author: byroot

activerecord/lib/active_record/attribute_methods/primary_key.rb

@@ -92,7 +92,7 @@ def composite_primary_key? # :nodoc:
           # Returns a quoted version of the primary key name, used to construct
           # SQL statements.
           def quoted_primary_key
-            @quoted_primary_key ||= connection.quote_column_name(primary_key)
+            @quoted_primary_key ||= adapter_class.quote_column_name(primary_key)
           end
 
           def reset_primary_key # :nodoc:

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

@@ -7,6 +7,67 @@ module ActiveRecord
   module ConnectionAdapters # :nodoc:
     # = Active Record Connection Adapters \Quoting
     module Quoting
+      extend ActiveSupport::Concern
+
+      module ClassMethods # :nodoc:
+        # Regexp for column names (with or without a table name prefix).
+        # Matches the following:
+        #
+        #   "#{table_name}.#{column_name}"
+        #   "#{column_name}"
+        def column_name_matcher
+          /
+            \A
+            (
+              (?:
+                # table_name.column_name | function(one or no argument)
+                ((?:\w+\.)?\w+ | \w+\((?:|\g<2>)\))
+              )
+              (?:(?:\s+AS)?\s+\w+)?
+            )
+            (?:\s*,\s*\g<1>)*
+            \z
+          /ix
+        end
+
+        # Regexp for column names with order (with or without a table name prefix,
+        # with or without various order modifiers). Matches the following:
+        #
+        #   "#{table_name}.#{column_name}"
+        #   "#{table_name}.#{column_name} #{direction}"
+        #   "#{table_name}.#{column_name} #{direction} NULLS FIRST"
+        #   "#{table_name}.#{column_name} NULLS LAST"
+        #   "#{column_name}"
+        #   "#{column_name} #{direction}"
+        #   "#{column_name} #{direction} NULLS FIRST"
+        #   "#{column_name} NULLS LAST"
+        def column_name_with_order_matcher
+          /
+            \A
+            (
+              (?:
+                # table_name.column_name | function(one or no argument)
+                ((?:\w+\.)?\w+ | \w+\((?:|\g<2>)\))
+              )
+              (?:\s+ASC|\s+DESC)?
+              (?:\s+NULLS\s+(?:FIRST|LAST))?
+            )
+            (?:\s*,\s*\g<1>)*
+            \z
+          /ix
+        end
+
+        # Quotes the column name. Must be implemented by subclasses
+        def quote_column_name(column_name)
+          raise NotImplementedError
+        end
+
+        # Quotes the table name. Defaults to column name quoting.
+        def quote_table_name(table_name)
+          quote_column_name(table_name)
+        end
+      end
+
       # Quotes the column value to help prevent
       # {SQL injection attacks}[https://en.wikipedia.org/wiki/SQL_injection].
       def quote(value)
@@ -71,14 +132,14 @@ def quote_string(s)
         s.gsub("\\", '\&\&').gsub("'", "''") # ' (for ruby-mode)
       end
 
-      # Quotes the column name. Defaults to no quoting.
+      # Quotes the column name.
       def quote_column_name(column_name)
-        column_name.to_s
+        self.class.quote_column_name(column_name)
       end
 
-      # Quotes the table name. Defaults to column name quoting.
+      # Quotes the table name.
       def quote_table_name(table_name)
-        quote_column_name(table_name)
+        self.class.quote_table_name(table_name)
       end
 
       # Override to return the quoted table name for assignment. Defaults to
@@ -159,59 +220,6 @@ def sanitize_as_sql_comment(value) # :nodoc:
         comment
       end
 
-      def column_name_matcher # :nodoc:
-        COLUMN_NAME
-      end
-
-      def column_name_with_order_matcher # :nodoc:
-        COLUMN_NAME_WITH_ORDER
-      end
-
-      # Regexp for column names (with or without a table name prefix).
-      # Matches the following:
-      #
-      #   "#{table_name}.#{column_name}"
-      #   "#{column_name}"
-      COLUMN_NAME = /
-        \A
-        (
-          (?:
-            # table_name.column_name | function(one or no argument)
-            ((?:\w+\.)?\w+ | \w+\((?:|\g<2>)\))
-          )
-          (?:(?:\s+AS)?\s+\w+)?
-        )
-        (?:\s*,\s*\g<1>)*
-        \z
-      /ix
-
-      # Regexp for column names with order (with or without a table name prefix,
-      # with or without various order modifiers). Matches the following:
-      #
-      #   "#{table_name}.#{column_name}"
-      #   "#{table_name}.#{column_name} #{direction}"
-      #   "#{table_name}.#{column_name} #{direction} NULLS FIRST"
-      #   "#{table_name}.#{column_name} NULLS LAST"
-      #   "#{column_name}"
-      #   "#{column_name} #{direction}"
-      #   "#{column_name} #{direction} NULLS FIRST"
-      #   "#{column_name} NULLS LAST"
-      COLUMN_NAME_WITH_ORDER = /
-        \A
-        (
-          (?:
-            # table_name.column_name | function(one or no argument)
-            ((?:\w+\.)?\w+ | \w+\((?:|\g<2>)\))
-          )
-          (?:\s+ASC|\s+DESC)?
-          (?:\s+NULLS\s+(?:FIRST|LAST))?
-        )
-        (?:\s*,\s*\g<1>)*
-        \z
-      /ix
-
-      private_constant :COLUMN_NAME, :COLUMN_NAME_WITH_ORDER
-
       private
         def type_casted_binds(binds)
           binds.map do |value|

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

@@ -6,9 +6,52 @@ module ActiveRecord
   module ConnectionAdapters
     module MySQL
       module Quoting # :nodoc:
+        extend ActiveSupport::Concern
+
         QUOTED_COLUMN_NAMES = Concurrent::Map.new # :nodoc:
         QUOTED_TABLE_NAMES = Concurrent::Map.new # :nodoc:
 
+        module ClassMethods # :nodoc:
+          def column_name_matcher
+            /
+              \A
+              (
+                (?:
+                  # `table_name`.`column_name` | function(one or no argument)
+                  ((?:\w+\.|`\w+`\.)?(?:\w+|`\w+`) | \w+\((?:|\g<2>)\))
+                )
+                (?:(?:\s+AS)?\s+(?:\w+|`\w+`))?
+              )
+              (?:\s*,\s*\g<1>)*
+              \z
+            /ix
+          end
+
+          def column_name_with_order_matcher
+            /
+              \A
+              (
+                (?:
+                  # `table_name`.`column_name` | function(one or no argument)
+                  ((?:\w+\.|`\w+`\.)?(?:\w+|`\w+`) | \w+\((?:|\g<2>)\))
+                )
+                (?:\s+COLLATE\s+(?:\w+|"\w+"))?
+                (?:\s+ASC|\s+DESC)?
+              )
+              (?:\s*,\s*\g<1>)*
+              \z
+            /ix
+          end
+
+          def quote_column_name(name)
+            QUOTED_COLUMN_NAMES[name] ||= "`#{name.to_s.gsub('`', '``')}`".freeze
+          end
+
+          def quote_table_name(name)
+            QUOTED_TABLE_NAMES[name] ||= "`#{name.to_s.gsub('`', '``').gsub(".", "`.`")}`".freeze
+          end
+        end
+
         def cast_bound_value(value)
           case value
           when Rational
@@ -26,14 +69,6 @@ def cast_bound_value(value)
           end
         end
 
-        def quote_column_name(name)
-          QUOTED_COLUMN_NAMES[name] ||= "`#{super.gsub('`', '``')}`".freeze
-        end
-
-        def quote_table_name(name)
-          QUOTED_TABLE_NAMES[name] ||= -super.gsub(".", "`.`").freeze
-        end
-
         def unquoted_true
           1
         end
@@ -81,43 +116,6 @@ def type_cast(value) # :nodoc:
             super
           end
         end
-
-        def column_name_matcher
-          COLUMN_NAME
-        end
-
-        def column_name_with_order_matcher
-          COLUMN_NAME_WITH_ORDER
-        end
-
-        COLUMN_NAME = /
-          \A
-          (
-            (?:
-              # `table_name`.`column_name` | function(one or no argument)
-              ((?:\w+\.|`\w+`\.)?(?:\w+|`\w+`) | \w+\((?:|\g<2>)\))
-            )
-            (?:(?:\s+AS)?\s+(?:\w+|`\w+`))?
-          )
-          (?:\s*,\s*\g<1>)*
-          \z
-        /ix
-
-        COLUMN_NAME_WITH_ORDER = /
-          \A
-          (
-            (?:
-              # `table_name`.`column_name` | function(one or no argument)
-              ((?:\w+\.|`\w+`\.)?(?:\w+|`\w+`) | \w+\((?:|\g<2>)\))
-            )
-            (?:\s+COLLATE\s+(?:\w+|"\w+"))?
-            (?:\s+ASC|\s+DESC)?
-          )
-          (?:\s*,\s*\g<1>)*
-          \z
-        /ix
-
-        private_constant :COLUMN_NAME, :COLUMN_NAME_WITH_ORDER
       end
     end
   end