diff options
Diffstat (limited to 'activerecord/lib/active_record/associations.rb')
| -rw-r--r-- | activerecord/lib/active_record/associations.rb | 62 |
1 files changed, 32 insertions, 30 deletions
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb index 4979113b0b..1c7209e64e 100644 --- a/activerecord/lib/active_record/associations.rb +++ b/activerecord/lib/active_record/associations.rb @@ -469,9 +469,9 @@ module ActiveRecord # === Association Join Models # # Has Many associations can be configured with the <tt>:through</tt> option to use an - # explicit join model to retrieve the data. This operates similarly to a - # +has_and_belongs_to_many+ association. The advantage is that you're able to add validations, - # callbacks, and extra attributes on the join model. Consider the following schema: + # explicit join model to retrieve the data. This operates similarly to a + # +has_and_belongs_to_many+ association. The advantage is that you're able to add validations, + # callbacks, and extra attributes on the join model. Consider the following schema: # # class Author < ActiveRecord::Base # has_many :authorships @@ -528,7 +528,7 @@ module ActiveRecord # @group.avatars # selects all avatars by going through the User join model. # # An important caveat with going through +has_one+ or +has_many+ associations on the - # join model is that these associations are *read-only*. For example, the following + # join model is that these associations are *read-only*. For example, the following # would not work following the previous example: # # @group.avatars << Avatar.new # this would work if User belonged_to Avatar rather than the other way around @@ -596,7 +596,7 @@ module ActiveRecord # === Polymorphic Associations # # Polymorphic associations on models are not restricted on what types of models they - # can be associated with. Rather, they specify an interface that a +has_many+ association + # can be associated with. Rather, they specify an interface that a +has_many+ association # must adhere to. # # class Asset < ActiveRecord::Base @@ -610,7 +610,7 @@ module ActiveRecord # @asset.attachable = @post # # This works by using a type column in addition to a foreign key to specify the associated - # record. In the Asset example, you'd need an +attachable_id+ integer column and an + # record. In the Asset example, you'd need an +attachable_id+ integer column and an # +attachable_type+ string column. # # Using polymorphic associations in combination with single table inheritance (STI) is @@ -666,7 +666,7 @@ module ActiveRecord # # Consider the following loop using the class above: # - # for post in Post.all + # Post.all.each do |post| # puts "Post: " + post.title # puts "Written by: " + post.author.name # puts "Last comment on: " + post.comments.first.created_on @@ -675,7 +675,7 @@ module ActiveRecord # To iterate over these one hundred posts, we'll generate 201 database queries. Let's # first just optimize it for retrieving the author: # - # for post in Post.find(:all, :include => :author) + # Post.find(:all, :include => :author).each do |post| # # This references the name of the +belongs_to+ association that also used the <tt>:author</tt> # symbol. After loading the posts, find will collect the +author_id+ from each one and load @@ -684,7 +684,7 @@ module ActiveRecord # # We can improve upon the situation further by referencing both associations in the finder with: # - # for post in Post.find(:all, :include => [ :author, :comments ]) + # Post.find(:all, :include => [ :author, :comments ]).each do |post| # # This will load all comments with a single query. This reduces the total number of queries # to 3. More generally the number of queries will be 1 plus the number of associations @@ -692,7 +692,7 @@ module ActiveRecord # # To include a deep hierarchy of associations, use a hash: # - # for post in Post.find(:all, :include => [ :author, { :comments => { :author => :gravatar } } ]) + # Post.find(:all, :include => [ :author, { :comments => { :author => :gravatar } } ]).each do |post| # # That'll grab not only all the comments but all their authors and gravatar pictures. # You can mix and match symbols, arrays and hashes in any combination to describe the @@ -741,7 +741,7 @@ module ActiveRecord # Picture.find(:first, :include => :most_recent_comments).most_recent_comments # => returns all associated comments. # # When eager loaded, conditions are interpolated in the context of the model class, not - # the model instance. Conditions are lazily interpolated before the actual model exists. + # the model instance. Conditions are lazily interpolated before the actual model exists. # # Eager loading is supported with polymorphic associations. # @@ -765,7 +765,7 @@ module ActiveRecord # == Table Aliasing # # Active Record uses table aliasing in the case that a table is referenced multiple times - # in a join. If a table is referenced only once, the standard table name is used. The + # in a join. If a table is referenced only once, the standard table name is used. The # second time, the table is aliased as <tt>#{reflection_name}_#{parent_table_name}</tt>. # Indexes are appended for any more successive uses of the table name. # @@ -847,7 +847,7 @@ module ActiveRecord # == Bi-directional associations # # When you specify an association there is usually an association on the associated model - # that specifies the same relationship in reverse. For example, with the following models: + # that specifies the same relationship in reverse. For example, with the following models: # # class Dungeon < ActiveRecord::Base # has_many :traps @@ -864,9 +864,9 @@ module ActiveRecord # # The +traps+ association on +Dungeon+ and the +dungeon+ association on +Trap+ are # the inverse of each other and the inverse of the +dungeon+ association on +EvilWizard+ - # is the +evil_wizard+ association on +Dungeon+ (and vice-versa). By default, + # is the +evil_wizard+ association on +Dungeon+ (and vice-versa). By default, # Active Record doesn't know anything about these inverse relationships and so no object - # loading optimisation is possible. For example: + # loading optimisation is possible. For example: # # d = Dungeon.first # t = d.traps.first @@ -876,8 +876,8 @@ module ActiveRecord # # The +Dungeon+ instances +d+ and <tt>t.dungeon</tt> in the above example refer to # the same object data from the database, but are actually different in-memory copies - # of that data. Specifying the <tt>:inverse_of</tt> option on associations lets you tell - # Active Record about inverse relationships and it will optimise object loading. For + # of that data. Specifying the <tt>:inverse_of</tt> option on associations lets you tell + # Active Record about inverse relationships and it will optimise object loading. For # example, if we changed our model definitions to: # # class Dungeon < ActiveRecord::Base @@ -1060,7 +1060,7 @@ module ActiveRecord # specify it with this option. # [:conditions] # Specify the conditions that the associated objects must meet in order to be included as a +WHERE+ - # SQL fragment, such as <tt>price > 5 AND name LIKE 'B%'</tt>. Record creations from + # SQL fragment, such as <tt>price > 5 AND name LIKE 'B%'</tt>. Record creations from # the association are scoped if a hash is used. # <tt>has_many :posts, :conditions => {:published => true}</tt> will create published # posts with <tt>@blog.posts.create</tt> or <tt>@blog.posts.build</tt>. @@ -1075,10 +1075,11 @@ module ActiveRecord # Specify the method that returns the primary key used for the association. By default this is +id+. # [:dependent] # If set to <tt>:destroy</tt> all the associated objects are destroyed - # alongside this object by calling their +destroy+ method. If set to <tt>:delete_all</tt> all associated - # objects are deleted *without* calling their +destroy+ method. If set to <tt>:nullify</tt> all associated + # alongside this object by calling their +destroy+ method. If set to <tt>:delete_all</tt> all associated + # objects are deleted *without* calling their +destroy+ method. If set to <tt>:nullify</tt> all associated # objects' foreign keys are set to +NULL+ *without* calling their +save+ callbacks. If set to - # <tt>:restrict</tt> this object cannot be deleted if it has any associated object. + # <tt>:restrict</tt> this object raises an <tt>ActiveRecord::DeleteRestrictionError</tt> exception and + # cannot be deleted if it has any associated objects. # # If using with the <tt>:through</tt> option, the association on the join model must be # a +belongs_to+, and the records which get deleted are the join records, rather than @@ -1227,7 +1228,8 @@ module ActiveRecord # If set to <tt>:destroy</tt>, the associated object is destroyed when this object is. If set to # <tt>:delete</tt>, the associated object is deleted *without* calling its destroy method. # If set to <tt>:nullify</tt>, the associated object's foreign key is set to +NULL+. - # Also, association is assigned. + # Also, association is assigned. If set to <tt>:restrict</tt> this object raises an + # <tt>ActiveRecord::DeleteRestrictionError</tt> exception and cannot be deleted if it has any associated object. # [:foreign_key] # Specify the foreign key used for the association. By default this is guessed to be the name # of this class in lower-case and "_id" suffixed. So a Person class that makes a +has_one+ association @@ -1243,7 +1245,7 @@ module ActiveRecord # you want to do a join but not include the joined columns. Do not forget to include the # primary and foreign keys, otherwise it will raise an error. # [:through] - # Specifies a Join Model through which to perform the query. Options for <tt>:class_name</tt>, + # Specifies a Join Model through which to perform the query. Options for <tt>:class_name</tt>, # <tt>:primary_key</tt>, and <tt>:foreign_key</tt> are ignored, as the association uses the # source reflection. You can only use a <tt>:through</tt> query through a <tt>has_one</tt> # or <tt>belongs_to</tt> association on the join model. @@ -1265,7 +1267,7 @@ module ActiveRecord # By default, only save the associated object if it's a new record. # [:inverse_of] # Specifies the name of the <tt>belongs_to</tt> association on the associated object - # that is the inverse of this <tt>has_one</tt> association. Does not work in combination + # that is the inverse of this <tt>has_one</tt> association. Does not work in combination # with <tt>:through</tt> or <tt>:as</tt> options. # See ActiveRecord::Associations::ClassMethods's overview on Bi-directional associations for more detail. # @@ -1383,7 +1385,7 @@ module ActiveRecord # will be updated with the current time in addition to the updated_at/on attribute. # [:inverse_of] # Specifies the name of the <tt>has_one</tt> or <tt>has_many</tt> association on the associated - # object that is the inverse of this <tt>belongs_to</tt> association. Does not work in + # object that is the inverse of this <tt>belongs_to</tt> association. Does not work in # combination with the <tt>:polymorphic</tt> options. # See ActiveRecord::Associations::ClassMethods's overview on Bi-directional associations for more detail. # @@ -1403,15 +1405,15 @@ module ActiveRecord end # Specifies a many-to-many relationship with another class. This associates two classes via an - # intermediate join table. Unless the join table is explicitly specified as an option, it is + # intermediate join table. Unless the join table is explicitly specified as an option, it is # guessed using the lexical order of the class names. So a join between Developer and Project # will give the default join table name of "developers_projects" because "D" outranks "P". - # Note that this precedence is calculated using the <tt><</tt> operator for String. This + # Note that this precedence is calculated using the <tt><</tt> operator for String. This # means that if the strings are of different lengths, and the strings are equal when compared # up to the shortest length, then the longer string is considered of higher - # lexical precedence than the shorter one. For example, one would expect the tables "paper_boxes" and "papers" + # lexical precedence than the shorter one. For example, one would expect the tables "paper_boxes" and "papers" # to generate a join table name of "papers_paper_boxes" because of the length of the name "paper_boxes", - # but it in fact generates a join table name of "paper_boxes_papers". Be aware of this caveat, and use the + # but it in fact generates a join table name of "paper_boxes_papers". Be aware of this caveat, and use the # custom <tt>:join_table</tt> option if you need to. # # The join table should not have a primary key or a model associated with it. You must manually generate the @@ -1513,7 +1515,7 @@ module ActiveRecord # the association will use "project_id" as the default <tt>:association_foreign_key</tt>. # [:conditions] # Specify the conditions that the associated object must meet in order to be included as a +WHERE+ - # SQL fragment, such as <tt>authorized = 1</tt>. Record creations from the association are + # SQL fragment, such as <tt>authorized = 1</tt>. Record creations from the association are # scoped if a hash is used. # <tt>has_many :posts, :conditions => {:published => true}</tt> will create published posts with <tt>@blog.posts.create</tt> # or <tt>@blog.posts.build</tt>. |