Don't require a DB connection when setting primary key.

Closes #2807.

2 files changed, 4 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/primary_key.rb b/activerecord/lib/active_record/attribute_methods/primary_key.rb
index ed71b5e7d4..a404a5edd7 100644
--- a/activerecord/lib/active_record/attribute_methods/primary_key.rb
+++ b/activerecord/lib/active_record/attribute_methods/primary_key.rb
@@ -66,7 +66,6 @@ module ActiveRecord
           @primary_key ||= ''
           self.original_primary_key = @primary_key
           value &&= value.to_s
-          connection_pool.primary_keys[table_name] = value
           self.primary_key = block_given? ? instance_eval(&block) : value
         end
       end
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 558b341c06..78159d13d4 100644
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -707,6 +707,10 @@ module ActiveRecord #:nodoc:
 
       # Returns an array of column objects for the table associated with this class.
       def columns
+        if defined?(@primary_key)
+          connection_pool.primary_keys[table_name] ||= primary_key
+        end
+
         connection_pool.columns[table_name]
       end