| Module | Sequel::Model::Associations::ClassMethods |
| In: |
lib/sequel/model/associations.rb
|
Each kind of association adds a number of instance methods to the model class which are specialized according to the association type and optional parameters given in the definition. Example:
class Project < Sequel::Model
many_to_one :portfolio
one_to_many :milestones
# or: many_to_many :milestones
end
The project class now has the following instance methods:
If you want to override the behavior of the add_/remove_/remove_all_ methods, there are private instance methods created that a prepended with an underscore (e.g. _add_milestone). The private instance methods can be easily overridden, but you shouldn‘t override the public instance methods without calling super, as they deal with callbacks and caching.
By default the classes for the associations are inferred from the association name, so for example the Project#portfolio will return an instance of Portfolio, and Project#milestones will return an array of Milestone instances.
Association definitions are also reflected by the class, e.g.:
Project.associations
=> [:portfolio, :milestones]
Project.association_reflection(:portfolio)
=> {:type => :many_to_one, :name => :portfolio, :class_name => "Portfolio"}
| association_reflections | [R] | All association reflections defined for this model (default: none). |
Associates a related model with the current model. The following types are supported:
A one to one relationship can be set up with a many_to_one association on the table with the foreign key, and a one_to_many association with the :one_to_one option specified on the table without the foreign key. The two associations will operate similarly, except that the many_to_one association setter doesn‘t update the database until you call save manually. Also, in most cases you need to specify the plural association name when using one_to_many with the :one_to_one option.
The following options can be supplied:
# File lib/sequel/model/associations.rb, line 486
486: def associate(type, name, opts = {}, &block)
487: raise(Error, 'invalid association type') unless assoc_class = ASSOCIATION_TYPES[type]
488: raise(Error, 'Model.associate name argument must be a symbol') unless Symbol === name
489:
490: # merge early so we don't modify opts
491: orig_opts = opts.dup
492: orig_opts = association_reflection(opts[:clone])[:orig_opts].merge(orig_opts) if opts[:clone]
493: opts = orig_opts.merge(:type => type, :name => name, :cache => true, :model => self)
494: opts[:block] = block if block
495: opts = assoc_class.new.merge!(opts)
496: opts[:eager_block] = block unless opts.include?(:eager_block)
497: opts[:graph_join_type] ||= :left_outer
498: opts[:order_eager_graph] = true unless opts.include?(:order_eager_graph)
499: conds = opts[:conditions]
500: opts[:graph_conditions] = conds if !opts.include?(:graph_conditions) and Sequel.condition_specifier?(conds)
501: opts[:graph_conditions] = opts[:graph_conditions] ? opts[:graph_conditions].to_a : []
502: opts[:graph_select] = Array(opts[:graph_select]) if opts[:graph_select]
503: [:before_add, :before_remove, :after_add, :after_remove, :after_load, :extend].each do |cb_type|
504: opts[cb_type] = Array(opts[cb_type])
505: end
506:
507: # find class
508: case opts[:class]
509: when String, Symbol
510: # Delete :class to allow late binding
511: opts[:class_name] ||= opts.delete(:class).to_s
512: when Class
513: opts[:class_name] ||= opts[:class].name
514: end
515:
516: send("def_#{type}""def_#{type}", opts)
517:
518: orig_opts.delete(:clone)
519: orig_opts.merge!(:class_name=>opts[:class_name], :class=>opts[:class], :block=>block)
520: opts[:orig_opts] = orig_opts
521: # don't add to association_reflections until we are sure there are no errors
522: association_reflections[name] = opts
523: end
The association reflection hash for the association of the given name.
# File lib/sequel/model/associations.rb, line 526
526: def association_reflection(name)
527: association_reflections[name]
528: end
Modify and return eager loading dataset based on association options
# File lib/sequel/model/associations.rb, line 536
536: def eager_loading_dataset(opts, ds, select, associations)
537: ds = ds.select(*select) if select
538: ds = ds.filter(opts[:conditions]) if opts[:conditions]
539: ds = ds.order(*opts[:order]) if opts[:order]
540: ds = ds.eager(opts[:eager]) if opts[:eager]
541: ds = ds.eager_graph(opts[:eager_graph]) if opts[:eager_graph]
542: ds = ds.eager(associations) unless Array(associations).empty?
543: ds = opts[:eager_block].call(ds) if opts[:eager_block]
544: ds
545: end
Copy the association reflections to the subclass
# File lib/sequel/model/associations.rb, line 548
548: def inherited(subclass)
549: super
550: subclass.instance_variable_set(:@association_reflections, @association_reflections.dup)
551: end
Shortcut for adding a many_to_many association, see associate
# File lib/sequel/model/associations.rb, line 554
554: def many_to_many(*args, &block)
555: associate(:many_to_many, *args, &block)
556: end
Shortcut for adding a many_to_one association, see associate
# File lib/sequel/model/associations.rb, line 559
559: def many_to_one(*args, &block)
560: associate(:many_to_one, *args, &block)
561: end
Shortcut for adding a one_to_many association, see associate
# File lib/sequel/model/associations.rb, line 564
564: def one_to_many(*args, &block)
565: associate(:one_to_many, *args, &block)
566: end