1 files changed, 14 insertions, 1 deletions
diff --git a/activerecord/lib/active_record/errors.rb b/activerecord/lib/active_record/errors.rb
index ea1709cb1f..96870cb338 100644
--- a/activerecord/lib/active_record/errors.rb
+++ b/activerecord/lib/active_record/errors.rb
@@ -87,7 +87,7 @@ module ActiveRecord
   #
   # For example, in
   #
-  #   Location.find :all, :conditions => ["lat = ? AND lng = ?", 53.7362]
+  #   Location.where("lat = ? AND lng = ?", 53.7362)
   #
   # two placeholders are given but only one variable to fill them.
   class PreparedStatementInvalid < ActiveRecordError
@@ -169,4 +169,17 @@ module ActiveRecord
       @errors = errors
     end
   end
+
+  # Raised when a primary key is needed, but there is not one specified in the schema or model.
+  class UnknownPrimaryKey < ActiveRecordError
+    attr_reader :model
+
+    def initialize(model)
+      @model = model
+    end
+
+    def message
+      "Unknown primary key for table #{model.table_name} in model #{model}."
+    end
+  end
 end