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Runtime conditions for associations should use procs

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The association guide previously recommended using a trick with single
quote delaying of string interpolation in order to handle setting association
conditions that would be evaluated at runtime. Using a proc is the new way as
this no longer works.
This commit is contained in:
Stephen Pike 2011-10-11 09:32:23 -04:00
parent 3ca269674f
commit c4e2954172
1 changed files with 2 additions and 4 deletions
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6
railties/guides/source/association_basics.textile
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@ -1229,17 +1229,15 @@ 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:
If you need to evaluate conditions dynamically at runtime, use a proc:
<ruby>
class Customer < ActiveRecord::Base
has_many :latest_orders, :class_name => "Order",
:conditions => 'orders.created_at > #{10.hours.ago.to_s(:db).inspect}'
:conditions => proc { "orders.created_at > #{10.hours.ago.to_s(:db).inspect}" }
end
</ruby>
Be sure to use single quotes.
h6(#has_many-counter_sql). +: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.