Hi
I have following models
class Room < ActiveRecord::Base
belongs_to :roomtype, :foreign_key=>''t_name''
end
class Roomtype < ActiveRecord::Base
has_many :rooms
accepts_nested_attributes_for :rooms
end
and the following tables
class CreateRoomtypes < ActiveRecord::Migration
create_table :roomtypes do |t|
t.string :t_name
t.string :rate
t.string :comment
t.timestamps
end
end
class CreateRooms < ActiveRecord::Migration
create_table :rooms do |t|
t.string :name
t.boolean :avail
t.string :type_name - to reference Roomtype''s name
t.timestamps
end
end
I want to use type_name column of Rooms as foreign key to Roomtype
model. I tried running below queries but in vein. What am I doing
wrong? How to ''plumb these together''?
ruby-1.9.2-p0 > Roomtype.first
=> #<Roomtype id: 1, t_name: "type1", rate: "100",
comment: nil,
created_at: "2010-10-19 05:33:50", updated_at: "2010-10-19
05:33:50">
ruby-1.9.2-p0 > Room.first
=> #<Room id: 1, name: "201", avail: true, created_at:
"2010-10-19
05:33:50", updated_at: "2010-10-19 05:44:32", type_name:
"type1">
ruby-1.9.2-p0 > Room.first.roomtype
=> nil
--i was expecting type1 here since the foreign key was t_name which
has type1 value.
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I found I needed to use :primary_key => ''type_name'' in the room model. I come from DB world and I know a primary key is one that shouldn''t be duplicated, so I am confused why I am telling the foreign key as primary_key in rails and the reference column in the parent as foreign_key. On Oct 19, 1:02 am, Arun Srini <arunro...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> Hi > I have following models > > class Room < ActiveRecord::Base > belongs_to :roomtype, :foreign_key=>''t_name'' > end > > class Roomtype < ActiveRecord::Base > has_many :rooms > accepts_nested_attributes_for :rooms > end > > and the following tables > > class CreateRoomtypes < ActiveRecord::Migration > create_table :roomtypes do |t| > t.string :t_name > t.string :rate > t.string :comment > > t.timestamps > end > end > class CreateRooms < ActiveRecord::Migration > create_table :rooms do |t| > t.string :name > t.boolean :avail > t.string :type_name - to reference Roomtype''s name > > t.timestamps > end > end > > I want to use type_name column of Rooms as foreign key to Roomtype > model. I tried running below queries but in vein. What am I doing > wrong? How to ''plumb these together''? > > ruby-1.9.2-p0 > Roomtype.first > => #<Roomtype id: 1, t_name: "type1", rate: "100", comment: nil, > created_at: "2010-10-19 05:33:50", updated_at: "2010-10-19 05:33:50"> > > ruby-1.9.2-p0 > Room.first > => #<Room id: 1, name: "201", avail: true, created_at: "2010-10-19 > 05:33:50", updated_at: "2010-10-19 05:44:32", type_name: "type1"> > > ruby-1.9.2-p0 > Room.first.roomtype > => nil > --i was expecting type1 here since the foreign key was t_name which > has type1 value.-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
On Oct 19, 7:17 am, Arun Srini <arunro...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> I found I needed to use :primary_key => ''type_name'' in the room model. > I come from DB world and I know a primary key is one that shouldn''t be > duplicated, so I am confused why I am telling the foreign key as > primary_key in rails and the reference column in the parent as > foreign_key. >Normally in a rails association the foreign key for a belongs to always refers to the other table''s primary key. If you want it to refer to a different column then, as you discovered, you use the primary_key option. Fred> On Oct 19, 1:02 am, Arun Srini <arunro...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote: > > > > > Hi > > I have following models > > > class Room < ActiveRecord::Base > > belongs_to :roomtype, :foreign_key=>''t_name'' > > end > > > class Roomtype < ActiveRecord::Base > > has_many :rooms > > accepts_nested_attributes_for :rooms > > end > > > and the following tables > > > class CreateRoomtypes < ActiveRecord::Migration > > create_table :roomtypes do |t| > > t.string :t_name > > t.string :rate > > t.string :comment > > > t.timestamps > > end > > end > > class CreateRooms < ActiveRecord::Migration > > create_table :rooms do |t| > > t.string :name > > t.boolean :avail > > t.string :type_name - to reference Roomtype''s name > > > t.timestamps > > end > > end > > > I want to use type_name column of Rooms as foreign key to Roomtype > > model. I tried running below queries but in vein. What am I doing > > wrong? How to ''plumb these together''? > > > ruby-1.9.2-p0 > Roomtype.first > > => #<Roomtype id: 1, t_name: "type1", rate: "100", comment: nil, > > created_at: "2010-10-19 05:33:50", updated_at: "2010-10-19 05:33:50"> > > > ruby-1.9.2-p0 > Room.first > > => #<Room id: 1, name: "201", avail: true, created_at: "2010-10-19 > > 05:33:50", updated_at: "2010-10-19 05:44:32", type_name: "type1"> > > > ruby-1.9.2-p0 > Room.first.roomtype > > => nil > > --i was expecting type1 here since the foreign key was t_name which > > has type1 value.-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
I think here room''s(associator for belongs_to) primary_key refers to room_type(associated) foreign_key. This was why I got confused. If the code was like class room belongs_to :room_type, foreign_key => ''type_name'', refers_to => ''t_name'' #(t_name - column in room_type class) end This would''ve been cleaner to think that the room''s type_name refers to room_type''s t_name column. Anyway.. me just getting to know if you don''t do it the rails way, its going to be tough way.... On Oct 19, 2:43 am, Frederick Cheung <frederick.che...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> On Oct 19, 7:17 am, Arun Srini <arunro...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> I found I needed to use :primary_key => ''type_name'' in the room model. > > I come from DB world and I know a primary key is one that shouldn''t be > > duplicated, so I am confused why I am telling the foreign key as > > primary_key in rails and the reference column in the parent as > > foreign_key. > > Normally in a rails association the foreign key for a belongs to > always refers to the other table''s primary key. If you want it to > refer to a different column then, as you discovered, you use the > primary_key option. > > Fred > > > > > On Oct 19, 1:02 am, Arun Srini <arunro...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote: > > > > Hi > > > I have following models > > > > class Room < ActiveRecord::Base > > > belongs_to :roomtype, :foreign_key=>''t_name'' > > > end > > > > class Roomtype < ActiveRecord::Base > > > has_many :rooms > > > accepts_nested_attributes_for :rooms > > > end > > > > and the following tables > > > > class CreateRoomtypes < ActiveRecord::Migration > > > create_table :roomtypes do |t| > > > t.string :t_name > > > t.string :rate > > > t.string :comment > > > > t.timestamps > > > end > > > end > > > class CreateRooms < ActiveRecord::Migration > > > create_table :rooms do |t| > > > t.string :name > > > t.boolean :avail > > > t.string :type_name - to reference Roomtype''s name > > > > t.timestamps > > > end > > > end > > > > I want to use type_name column of Rooms as foreign key to Roomtype > > > model. I tried running below queries but in vein. What am I doing > > > wrong? How to ''plumb these together''? > > > > ruby-1.9.2-p0 > Roomtype.first > > > => #<Roomtype id: 1, t_name: "type1", rate: "100", comment: nil, > > > created_at: "2010-10-19 05:33:50", updated_at: "2010-10-19 05:33:50"> > > > > ruby-1.9.2-p0 > Room.first > > > => #<Room id: 1, name: "201", avail: true, created_at: "2010-10-19 > > > 05:33:50", updated_at: "2010-10-19 05:44:32", type_name: "type1"> > > > > ruby-1.9.2-p0 > Room.first.roomtype > > > => nil > > > --i was expecting type1 here since the foreign key was t_name which > > > has type1 value.-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
Arun Srini wrote in post #955342:> > class CreateRoomtypes < ActiveRecord::Migration > create_table :roomtypes do |t| > t.string :t_name > t.string :rate > t.string :comment > t.timestamps > end > end > class CreateRooms < ActiveRecord::Migration > create_table :rooms do |t| > t.string :name > t.boolean :avail > t.string :type_name - to reference Roomtype''s name > > t.timestamps > end > end > > I want to use type_name column of Rooms as foreign key to Roomtype > model. I tried running below queries but in vein. What am I doing > wrong? How to ''plumb these together''? >Since you do seem to be defining the rooms table, why not use the rails ''traditional'' roomtypes_id field as your key? It is much clearer (I know what that field is, and I know where it connects to), it is the ''convention over configuration'' solution, and it alleviates any potential issue with someone in the future deciding that "Oh, that room type name doesn''t really fit anymore, can I change it?" - I personally abhor descriptive strings as keys for precisely that reason... Leave some of that DB world training behind and embrace the ''rails way'', you''ll be much happier, and things tend to fit more naturally. -- Posted via http://www.ruby-forum.com/. -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
Your argument was very fine, and I accept that. I am a hardcore DBA and SQL expert, with good data modelling experience, and have come across many models that needs to have multiple keys as prmary and foreign. Thus my quest to custom foreign keys. Anyway, the ''magic'' rails does is very interesting.. On Oct 19, 8:01 am, Ar Chron <li...-fsXkhYbjdPsEEoCn2XhGlw@public.gmane.org> wrote:> Arun Srini wrote in post #955342: > > > > > > > > > class CreateRoomtypes < ActiveRecord::Migration > > create_table :roomtypes do |t| > > t.string :t_name > > t.string :rate > > t.string :comment > > t.timestamps > > end > > end > > class CreateRooms < ActiveRecord::Migration > > create_table :rooms do |t| > > t.string :name > > t.boolean :avail > > t.string :type_name - to reference Roomtype''s name > > > t.timestamps > > end > > end > > > I want to use type_name column of Rooms as foreign key to Roomtype > > model. I tried running below queries but in vein. What am I doing > > wrong? How to ''plumb these together''? > > Since you do seem to be defining the rooms table, why not use the rails > ''traditional'' roomtypes_id field as your key? It is much clearer (I > know what that field is, and I know where it connects to), it is the > ''convention over configuration'' solution, and it alleviates any > potential issue with someone in the future deciding that "Oh, that room > type name doesn''t really fit anymore, can I change it?" - I personally > abhor descriptive strings as keys for precisely that reason... > > Leave some of that DB world training behind and embrace the ''rails way'', > you''ll be much happier, and things tend to fit more naturally. > > -- > Posted viahttp://www.ruby-forum.com/.-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
Arun Srini wrote in post #955420:> Your argument was very fine, and I accept that. I am a hardcore DBA > and SQL expert, with good data modelling experience,If that were true, then you''d know that your original schema is not normalized to 3NF and should not be used for general purposes.> and have come > across many models that needs to have multiple keys as prmary and > foreign. Thus my quest to custom foreign keys.You don''t need custom foreign keys for this. Just normalize your DB schema properly and you''ll most likely get something that Rails can work with.> Anyway, the ''magic'' rails does is very interesting..Best, -- Marnen Laibow-Koser http://www.marnen.org marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org -- Posted via http://www.ruby-forum.com/. -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
On Oct 19, 9:06 am, Marnen Laibow-Koser <li...-fsXkhYbjdPsEEoCn2XhGlw@public.gmane.org> wrote:> Arun Srini wrote in post #955420: > > > Your argument was very fine, and I accept that. I am a hardcore DBA > > and SQL expert, with good data modelling experience, > > If that were true, then you''d know that your original schema is not > normalized to 3NF and should not be used for general purposes.3NF - every non prime attribute int he table should be directly dependent on candidate key. I have room_type that is not directly dependent on key(or even storing the motel info in central table), and thus it''s not in 3rd NF. I understand that , no need of any personal comments here.> > > and have come > > across many models that needs to have multiple keys as prmary and > > foreign. Thus my quest to custom foreign keys. > > You don''t need custom foreign keys for this. Just normalize your DB > schema properly and you''ll most likely get something that Rails can work > with.I don''t need custom foreign keys here, all I was tellign was that there have been some cases where I needed more than one column to refer to parent column and wanted to do this in rails.> > > Anyway, the ''magic'' rails does is very interesting.. > > Best, > -- > Marnen Laibow-Koserhttp://www.marnen.org > mar...-sbuyVjPbboAdnm+yROfE0A@public.gmane.org > > -- > Posted viahttp://www.ruby-forum.com/.-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.