String interpolation conditions

1 files changed, 11 insertions, 0 deletions

diff --git a/railties/guides/source/association_basics.textile b/railties/guides/source/association_basics.textile
index 4d75fb6dc4..aaea83fa32 100644
--- a/railties/guides/source/association_basics.textile
+++ b/railties/guides/source/association_basics.textile
@@ -1219,6 +1219,17 @@ end
 
 If you use a hash-style +:conditions+ option, then record creation via this association will be automatically scoped using the hash. In this case, using +@customer.confirmed_orders.create+ or +@customer.confirmed_orders.build+ will create orders where the confirmed column has the value +true+.
 
+If you need to evaluate conditions dynamically at runtime, you could use string interpolation in single quotes:
+
+<ruby>
+class Customer < ActiveRecord::Base
+  has_many :latest_orders, :class_name => "Order",
+    :conditions => 'orders.created_at > #{10.hours.ago.to_s(:db).inspect}'
+end
+</ruby>
+
+Be sure to use single quotes.
+
 h6. +:counter_sql+
 
 Normally Rails automatically generates the proper SQL to count the association members. With the +:counter_sql+ option, you can specify a complete SQL statement to count them yourself.