I''m having trouble getting this right (ActiveRecord associations are my
weakness). Given two models:
Racers:
:racer_id
:name
TandemRacers:
:racer_1_id
:racer_2_id
:start (datetime)
:return (datetime)
How do I associate the models such that I can call a Riders coriders,
and also see what riders have ridden on a tandem? Not all Racers will
ride tandem, and those that do won''t ride them for the whole race.
TandemRacers will have it''s own controller.
So far I have:
class Racer < ActiveRecord::Base
has_and_belongs_to_many :coracers,
:class_name => "Racer",
:join_table => "tandem_racers",
:association_foreign_key => "racer_2_id",
:foreign_key => "racer_1_id"
end
I''m not sure what should in the TandemRacers model on the other end
though.
--
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-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---
Chris Bloom wrote:> I''m having trouble getting this right (ActiveRecord associations are my > weakness). Given two models: > > Racers: > :racer_id > :name > > TandemRacers: > :racer_1_id > :racer_2_id > :start (datetime) > :return (datetime) > > How do I associate the models such that I can call a Riders coriders, > and also see what riders have ridden on a tandem? Not all Racers will > ride tandem, and those that do won''t ride them for the whole race. > TandemRacers will have it''s own controller. > > So far I have: > class Racer < ActiveRecord::Base > has_and_belongs_to_many :coracers, > :class_name => "Racer", > :join_table => "tandem_racers", > :association_foreign_key => "racer_2_id", > :foreign_key => "racer_1_id" > end > > I''m not sure what should in the TandemRacers model on the other end > though.Is there really an "ordering" to the pairings. E.g. what does it mean for a racer to be racer_1 or racer_2? -- Michael Wang --~--~---------~--~----~------------~-------~--~----~ 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-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
Michael Wang wrote:> Is there really an "ordering" to the pairings. E.g. what does it mean > for a racer to be racer_1 or racer_2?No, there is no ordering. A tandem bike has two riders. It doesn''t matter what order. I could have called it front_racer, back_racer, etc. Ordering is not important, only the pairing. -- 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-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
Chris Bloom wrote:> Michael Wang wrote: >> Is there really an "ordering" to the pairings. E.g. what does it mean >> for a racer to be racer_1 or racer_2? > > No, there is no ordering. A tandem bike has two riders. It doesn''t > matter what order. I could have called it front_racer, back_racer, etc. > Ordering is not important, only the pairing.The problem that I''m facing is that I will need to be able to know: 1. If a rider was part of a tandem team, and if so how many times 2. The riders s/he was partnered with. However, this has to be done regardless of whether they were rider A or rider B. I don''t think a simple link table will work as it would require that for every pairing I have to enter 2 rows: A -> B and B -> A. Perhaps there is a way to do it using the :conditions or :finder_sql options of the association, but I''m not sure where to begin with those. Suggestions are appreciated :) -- 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-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
From: rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org [mailto:rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org] On Behalf Of Chris Bloom> The problem that I''m facing is that I will need to be able to know:1. If a rider was part of a tandem team, and if so how many times 2. The riders s/he was partnered with.< Would it help to introduce a Bike model? Some Bikes have two Riders; some have one. ///ark --~--~---------~--~----~------------~-------~--~----~ 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-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
Mark Wilden wrote:> From: rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org > [mailto:rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org] On Behalf Of Chris Bloom > >> The problem that I''m facing is that I will need to be able to know: > 1. If a rider was part of a tandem team, and if so how many times > 2. The riders s/he was partnered with.< > > Would it help to introduce a Bike model? Some Bikes have two Riders; > some > have one. > > ///arkI''m not sure that would help. I''m assuming that all racers will have and use a one-rider bike. However, part of the race involves the option of using a tandem bike for extra points. So, it''s assumed from the Racers table that they each have a one-rider bike. And there is only one tandem bike that will be shared - two riders at a time - and that''s what I am most interested in tracking - what two riders were on the bike. I suppose that it is less important to know who was paired with who, but I would like to know who rode the tandem bike at any given time, and perhaps how many times (though this will probably be 0 or 1) -- 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-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
-----Original Message----- From: rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org [mailto:rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org] On Behalf Of Chris Bloom Subject: [Rails] Re: Associating 2 Users in 1 modeled join table> Would it help to introduce a Bike model? Some Bikes have two Riders; > some have one.>So, it''s assumed from the Racers table that they each have a one-rider >bike. And there is only one tandem bike that will be shared - two riders >at a time - and that''s what I am most interested in tracking - what two >riders were on the bike. I suppose that it is less important to know who >was paired with who, but I would like to know who rode the tandem bike >at any given time, and perhaps how many times (though this will probably >be 0 or 1)If a Bike has_many Racers, then you could avoid the racer_1 and racer_2 columns. ///ark --~--~---------~--~----~------------~-------~--~----~ 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-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
On 10/4/07, Chris Bloom <rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:> > Chris Bloom wrote: > > Michael Wang wrote: > >> Is there really an "ordering" to the pairings. E.g. what does it mean > >> for a racer to be racer_1 or racer_2? > > > > No, there is no ordering. A tandem bike has two riders. It doesn''t > > matter what order. I could have called it front_racer, back_racer, etc. > > Ordering is not important, only the pairing. > > The problem that I''m facing is that I will need to be able to know: > 1. If a rider was part of a tandem team, and if so how many times > 2. The riders s/he was partnered with. > > However, this has to be done regardless of whether they were rider A or > rider B. I don''t think a simple link table will work as it would require > that for every pairing I have to enter 2 rows: A -> B and B -> A. > Perhaps there is a way to do it using the :conditions or :finder_sql > options of the association, but I''m not sure where to begin with those.Seems to me you need a model for a Rider, and another model for an "Event". The "Event" would represent a specific instance of a bike running a race, so it would have dates, times, etc. Since an "Event" (not sure that''s the best name) could have 1 or 2 riders, and any given rider could participate in multiple "Events", it looks like a habtm relationship to me. riders <-- events_riders --> events --~--~---------~--~----~------------~-------~--~----~ 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-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
-----Original Message----- From: rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org [mailto:rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org] On Behalf Of Bob Showalter Subject: [Rails] Re: Associating 2 Users in 1 modeled join table>Seems to me you need a model for a Rider, and another model for an >"Event". The "Event" would represent a specific instance of a bike >running a race, so it would have dates, times, etc.>Since an "Event" (not sure that''s the best name) could have 1 or 2 >riders, and any given rider could participate in multiple "Events", it >looks like a habtm relationship to me.> riders <-- events_riders --> eventsI think this is similar to what I was thinking about Bike, except that in my case, I would flatten the habtms by discriminating by Race (sorry, I just couldn''t resist!): Race has_many Bikes has_many Racers ///ark --~--~---------~--~----~------------~-------~--~----~ 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-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
Bob Showalter wrote:> Seems to me you need a model for a Rider, and another model for an > "Event". The "Event" would represent a specific instance of a bike > running a race, so it would have dates, times, etc. > > Since an "Event" (not sure that''s the best name) could have 1 or 2 > riders, and any given rider could participate in multiple "Events", it > looks like a habtm relationship to me. > > riders <-- events_riders --> eventsI understand that logic, but I''m not sure that''s an appropriate solution for this reason: This is a one-off application for a one-off race. No other racing events need to be tracked. Even if you consider an event to just be the fact that a racer is riding a bike in the race, they will always be riding at least one bike by virtue of signing up for the race, so that seems a bit redundant. These racers will typically be riding their own one-rider bikes but may, optionally, over the course of the single race, ride a tandem bike with another rider - It''s a silly race, what can I say... The other problem that I see with the suggested model is that it still doesn''t tell me who rode with whom. But I guess I did say that was less important, didn''t I? :) Really what I want from this is the ability to say Rider.CoRiders and get back Rider B, C and D, etc. Or to say Rider.tandem_rides.count, etc. If all else fails, I can always fall back to straight SQL and not worry about the mapping (this tool will be used for all of 2 hours, and could probably be done in Excel much easier, but looked like a good place to stretch my Rails muscles) Thanks for the proposed solutions. I appreciate the thought you''ve put into this. -- 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-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
On 10/4/07, Chris Bloom <rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:> > Bob Showalter wrote: > > Seems to me you need a model for a Rider, and another model for an > > "Event". The "Event" would represent a specific instance of a bike > > running a race, so it would have dates, times, etc. > > > > Since an "Event" (not sure that''s the best name) could have 1 or 2 > > riders, and any given rider could participate in multiple "Events", it > > looks like a habtm relationship to me. > > > > riders <-- events_riders --> events > > I understand that logic, but I''m not sure that''s an appropriate solution > for this reason: > > This is a one-off application for a one-off race. No other racing events > need to be tracked. Even if you consider an event to just be the fact > that a racer is riding a bike in the race, they will always be riding at > least one bike by virtue of signing up for the race, so that seems a bit > redundant. These racers will typically be riding their own one-rider > bikes but may, optionally, over the course of the single race, ride a > tandem bike with another rider - It''s a silly race, what can I say... > > The other problem that I see with the suggested model is that it still > doesn''t tell me who rode with whom. But I guess I did say that was less > important, didn''t I? :) > > Really what I want from this is the ability to say Rider.CoRiders and > get back Rider B, C and D, etc. Or to say Rider.tandem_rides.count, etc. > > If all else fails, I can always fall back to straight SQL and not worry > about the mapping (this tool will be used for all of 2 hours, and could > probably be done in Excel much easier, but looked like a good place to > stretch my Rails muscles) > > Thanks for the proposed solutions. I appreciate the thought you''ve put > into this. > --I''m thinking something like: class TandemRide has_and_belongs_to_many :riders # work out how to constrain/validate this to only two end class Rider < ActiveRecord::Base has_and_belongs_to_many :tandem_rides # Theres probably a better way to do this with sql, but if there aren''t too many riders # and rides this would probably work def co_riders_with_duplicates tandem_rides.inject([]) {|res, p| res << p.riders - [self]) end def co_riders co_riders_with_dupicates.uniq end end -- Rick DeNatale My blog on Ruby http://talklikeaduck.denhaven2.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-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
Rick Denatale wrote:> I''m thinking something like: > > > class TandemRide > has_and_belongs_to_many :riders > # work out how to constrain/validate this to only two > end > > class Rider < ActiveRecord::Base > > has_and_belongs_to_many :tandem_rides > > # Theres probably a better way to do this with sql, but if there > aren''t too many riders > # and rides this would probably work > def co_riders_with_duplicates > tandem_rides.inject([]) {|res, p| res << p.riders - [self]) > end > > def co_riders > co_riders_with_dupicates.uniq > end > end > -- > Rick DeNatale > > My blog on Ruby > http://talklikeaduck.denhaven2.com/Hmm, that looks interesting. But does that put me back to having two entries in tandemride for each pairing, A -> B and B -> A? If so, so be it. That''s easy enough to do and build constraints for. Also, what does the "- [self]" part of the inject block do? Thanks for the idea! -- 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-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
On 10/4/07, Chris Bloom <rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:> > Rick Denatale wrote: > > I''m thinking something like: > > > > > > class TandemRide > > has_and_belongs_to_many :riders > > # work out how to constrain/validate this to only two > > end > > > > class Rider < ActiveRecord::Base > > > > has_and_belongs_to_many :tandem_rides > > > > # Theres probably a better way to do this with sql, but if there > > aren''t too many riders > > # and rides this would probably work > > def co_riders_with_duplicates > > tandem_rides.inject([]) {|res, p| res << p.riders - [self]) > > end > > > > def co_riders > > co_riders_with_dupicates.uniq > > end > > end > > -- > > Rick DeNatale > > > > My blog on Ruby > > http://talklikeaduck.denhaven2.com/ > > Hmm, that looks interesting. But does that put me back to having two > entries in tandemride for each pairing, A -> B and B -> A? If so, so be > it. That''s easy enough to do and build constraints for.the tandemride table really only needs an id field, at least with the requirements you''ve given. You''ll need a riders_tandem_rides table to represent the habtm relationships Now lets say we had the following tandem rides Joe and Sally Joe and Sam Sally and Sam riders table id Name .... 1 Joe 2 Sally 3 Sam tandem_rides table id 1 2 3 iders_tandem_rides table rider_id tandem_ride_id 1 1 1 2 2 1 2 3 3 2 3 3> > Also, what does the "- [self]" part of the inject block do?It removes the rider himself from the list of his co_riders. Mind you, none of this is tested code. -- Rick DeNatale My blog on Ruby http://talklikeaduck.denhaven2.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-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
Rick Denatale wrote:> the tandemride table really only needs an id field, at least with the > requirements you''ve given. > > You''ll need a riders_tandem_rides table to represent the habtm > relationshipsAh, OK. I''ll try that. Thanks! -- 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-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
Rick Denatale wrote:> I''m thinking something like: > > > class TandemRide > has_and_belongs_to_many :riders > # work out how to constrain/validate this to only two > end > > class Rider < ActiveRecord::Base > > has_and_belongs_to_many :tandem_rides > > # Theres probably a better way to do this with sql, but if there > aren''t too many riders > # and rides this would probably work > def co_riders_with_duplicates > tandem_rides.inject([]) {|res, p| res << p.riders - [self]) > end > > def co_riders > co_riders_with_dupicates.uniq > end > endHi Rick, I had to make some changes to get it to work, but it works! Thanks!! Here''s what I ended up with: class Racer < ActiveRecord::Base has_and_belongs_to_many :tandem_rides, :class_name => "TandemRide" # Theres probably a better way to do this with sql, but if there # aren''t too many riders and rides this would probably work def co_riders_with_duplicates tandem_rides.inject([]) { |res, p| res << p.riders - [self] } end def co_riders co_riders_with_duplicates.flatten.uniq end end class TandemRide < ActiveRecord::Base has_and_belongs_to_many :riders, :class_name => "Racer" end So now, this works:>> t = TandemRide.create=> #<TandemRide:0x492bef0>>> t.riders << Racer.find(2)=> [#<Racer:0x490af34>]>> t.riders << Racer.find(3)=> [#<Racer:0x490af34>, #<Racer:0x4903b80>]>> r = Racer.find(2)=> #<Racer:0x48fbac0>>> r.tandem_rides=> [#<TandemRide:0x48f8fb4>]>> r.co_riders=> [#<Racer:0x48f6458>, #<Racer:0x48f4a18>] Thanks again!! -- 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-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---