Cache columns at the model level.

Allows two models to use the same table but have different primary keys.

3 files changed, 9 insertions, 17 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/primary_key.rb b/activerecord/lib/active_record/attribute_methods/primary_key.rb
index 0560f63949..e3c7344f59 100644
--- a/activerecord/lib/active_record/attribute_methods/primary_key.rb
+++ b/activerecord/lib/active_record/attribute_methods/primary_key.rb
@@ -102,8 +102,6 @@ module ActiveRecord
           @original_primary_key = @primary_key if defined?(@primary_key)
           @primary_key          = value && value.to_s
           @quoted_primary_key   = nil
-
-          connection.schema_cache.primary_keys[table_name] = @primary_key if connected?
         end
 
         def set_primary_key(value = nil, &block) #:nodoc:
diff --git a/activerecord/lib/active_record/connection_adapters/schema_cache.rb b/activerecord/lib/active_record/connection_adapters/schema_cache.rb
index bee03abd44..447e309f23 100644
--- a/activerecord/lib/active_record/connection_adapters/schema_cache.rb
+++ b/activerecord/lib/active_record/connection_adapters/schema_cache.rb
@@ -7,17 +7,10 @@ module ActiveRecord
 
       def initialize(conn)
         @connection = conn
-        @tables              = {}
+        @tables     = {}
 
         @columns     = Hash.new do |h, table_name|
-          h[table_name] =
-            # Fetch a list of columns
-            conn.columns(table_name, "#{table_name} Columns").tap do |cs|
-              # set primary key information
-              cs.each do |column|
-                column.primary = column.name == primary_keys[table_name]
-              end
-            end
+          h[table_name] = conn.columns(table_name, "#{table_name} Columns")
         end
 
         @columns_hash = Hash.new do |h, table_name|
diff --git a/activerecord/lib/active_record/model_schema.rb b/activerecord/lib/active_record/model_schema.rb
index 058161a2cb..9ed871a1cb 100644
--- a/activerecord/lib/active_record/model_schema.rb
+++ b/activerecord/lib/active_record/model_schema.rb
@@ -221,16 +221,16 @@ module ActiveRecord
 
       # Returns an array of column objects for the table associated with this class.
       def columns
-        if defined?(@primary_key)
-          connection.schema_cache.primary_keys[table_name] ||= primary_key
+        @columns ||= connection.schema_cache.columns[table_name].map do |col|
+          col = col.dup
+          col.primary = (col.name == primary_key)
+          col
         end
-
-        connection.schema_cache.columns[table_name]
       end
 
       # Returns a hash of column objects for the table associated with this class.
       def columns_hash
-        connection.schema_cache.columns_hash[table_name]
+        @columns_hash ||= Hash[columns.map { |c| [c.name, c] }]
       end
 
       # Returns a hash where the keys are column names and the values are
@@ -295,7 +295,8 @@ module ActiveRecord
         undefine_attribute_methods
         connection.schema_cache.clear_table_cache!(table_name) if table_exists?
 
-        @column_names = @content_columns = @column_defaults = @dynamic_methods_hash = @inheritance_column = nil
+        @column_names = @content_columns = @column_defaults = @columns = @columns_hash = nil
+        @dynamic_methods_hash = @inheritance_column = nil
         @arel_engine = @relation = nil
       end