Dear all Refer to http://guides.rails.info/association_basics.html Why :physician and :patient some with (s), and some not...? It actually refer to the class name or table name? ** really confuse >_<. Can someone explain it? Is it a convention of rail? Thank you. class Physician < ActiveRecord::Base has_many :appointments has_many :patients, :through => :appointments end class Appointment < ActiveRecord::Base belongs_to :physician belongs_to :patient end class Patient < ActiveRecord::Base has_many :appointments has_many :physicians, :through => :appointments end Many thanks Valentino
on 2009-02-11 17:19
on 2009-02-11 17:45
It is the convention in Rails A Physician (singular) has many appointments (plural) An Appointment (singular) belongs to one patient (singular) 2009/2/11 Valentino Lun <email@example.com>
on 2009-02-11 19:45
Valentino Lun wrote: > Dear all > > Refer to http://guides.rails.info/association_basics.html > > Why :physician and :patient some with (s), and some not...? It actually > refer to the class name or table name? ** really confuse >_<. Can > someone explain it? Is it a convention of rail? Thank you. My guess is that English is not your native language. This might be why you are confused by the Rails conventions, which follows English singular/plural conventions. Here's the scoop. I hope you can follow along: First let's look at a Rails model object. The model class is like a prototype (or template) representing a single row in a database table. This is why the model class name is singular. Example: class Physician < ActiveRecord::Base ... end The database table that stores each physician contains a collection of physicians, which is why the table name is plural. Rails associations can represent either one or many model objects. Associations described as either has_one or belongs_to represent one object and therefore use the singular form: Examples: class Appointment < ActiveRecord::Base has_one :physician # This is one Physician object (singular) end class Appointment < ActiveRecord::Base belongs_to :physician # This is one Physician object (singular) end Note: Notice that has_one is used for one side of a one-to-one association. There other side would use belongs_to. Example: class Unicycle << ActiveRecord::Base has_one :wheel end class Wheel << ActiveRecord::Base belongs_to :unicycle end Associations described as has_many refer to a collection (array) of objects and therefore use the plural form: Examples: class Physician < ActiveRecord::Base has_many :appointments # This is an array of Appointment objects (plural) end I hope this makes things a little more clear to you.
on 2009-02-12 02:22
It depends whether there are more than one or not. A class is the blueprint of an instance object. Thus a physician class describes one object, of class physician. Has many means one physician has a collection of some other kind of object. Belongs to means a physician can be part of A collection of physicians for another class of object and is therefore the other 'side' if you will. Blog: http://random8.zenunit.com/ Learn rails: http://sensei.zenunit.com/ On 12/02/2009, at 3:19 AM, Valentino Lun <firstname.lastname@example.org