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revises recent commit related to :uniq => true

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1 parent 44b752b commit 86d5c728fbbce6ba8ae73f8926084f5c0eee9a41 @fxn fxn committed Jul 9, 2010
Showing with 23 additions and 29 deletions.
  1. +1 −1 activerecord/lib/active_record/associations.rb
  2. +22 −28 railties/guides/source/association_basics.textile
@@ -889,7 +889,7 @@ module ClassMethods
# Specifies type of the source association used by <tt>has_many :through</tt> queries where the source
# association is a polymorphic +belongs_to+.
# [:uniq]
- # If true, duplicates will be omitted from the collection. Works only in conjunction with <tt>:through</tt>.
+ # If true, duplicates will be omitted from the collection. Useful in conjunction with <tt>:through</tt>.
# [:readonly]
# If true, all the associated objects are readonly through the association.
# [:validate]
@@ -1371,47 +1371,41 @@ The +:through+ option specifies a join model through which to perform the query.
h6(#has_many-uniq). +:uniq+
-Specify the +:uniq => true+ option to remove duplicates from the collection. It only works with +:through+ option.
+Set the +:uniq+ option to true to keep the collection free of duplicates. This is mostly useful together with the +:through+ option.
<ruby>
class Person < ActiveRecord::Base
- has_many :readers
- has_many :posts, :through => :readers
-
- def self.lab
- person = Person.create(:name => 'john')
- p = Post.create(:name => 'a1')
- person.posts << p
- person.posts << p
- person.reload
- puts person.posts.inspect #=> [#<Post id: 5, name: "a1">, #<Post id: 5, name: "a1">]
- puts Reader.all.inspect #=> [#<Reader id: 12, person_id: 5, post_id: 5>, #<Reader id: 13, person_id: 5, post_id: 5>]
- end
+ has_many :readings
+ has_many :posts, :through => :readings
end
+
+person = Person.create(:name => 'john')
+post = Post.create(:name => 'a1')
+person.posts << post
+person.posts << post
+person.posts.inspect # => [#<Post id: 5, name: "a1">, #<Post id: 5, name: "a1">]
+Reading.all.inspect # => [#<Reading id: 12, person_id: 5, post_id: 5>, #<Reading id: 13, person_id: 5, post_id: 5>]
</ruby>
-In the above case +readers+ table has two records and +person.posts+ brings out both of these records even though these records are basically pointing to the same +post+ record.
+In the above case there are two readings and +person.posts+ brings out both of them even though these records are pointing to the same post.
-Now let's add +uniq => true+ option.
+Now let's set +:uniq+ to true:
<ruby>
class Person
- has_many :readers
- has_many :posts, :through => :readers, :uniq => true
-
- def self.experiment
- person = Person.create(:name => 'honda')
- p = Post.create(:name => 'a1')
- person.posts << p
- person.posts << p
- person.reload
- puts person.posts.inspect #=> [#<Post id: 7, name: "a1">]
- puts Reader.all.inspect #=> [#<Reader id: 16, person_id: 7, post_id: 7>, #<Reader id: 17, person_id: 7, post_id: 7>]
- end
+ has_many :readings
+ has_many :posts, :through => :readings, :uniq => true
end
+
+person = Person.create(:name => 'honda')
+post = Post.create(:name => 'a1')
+person.posts << post
+person.posts << post
+person.posts.inspect # => [#<Post id: 7, name: "a1">]
+Reading.all.inspect # => [#<Reading id: 16, person_id: 7, post_id: 7>, #<Reading id: 17, person_id: 7, post_id: 7>]
</ruby>
-In the above case +readers+ table still has two records. However +person.posts+ will show only one +post+ record because collection will load only +unique+ records.
+In the above case there are still two readings. However +person.posts+ shows only one post because collection loads only unique records.
h6(#has_many-validate). +:validate+

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