Rails - Jul 2006 - has_many :through with multiple paths

Hi all.

I am currently thinking about how to do the following:

I have the following models.
Team
Person

Team has various positions (manager, programmer etc.) I would like each 
one of those positions to reference one or more Person records. A single 
Person record could be on 6 different teams at the same time in 
different roles. the same person could even be on the same team multiple 
times in different roles.

I am not 100% sure how to go about this. I am thinking that I will need 
something like an intermediate record.

teams_people
id
team_id
people_id
role

I would then have (I think) to have methods in the Team model that will 
find each person in the @team.people array based on the role.

I the end I want a view to have something like:

Team Name
Manager: Person1, Person 4
Programmer: Person2, Person 3
Designer: Person2
Lackey: Person3

With just a single find that :includes all the relevant people.

I apologise if this isn''t very clear. The joys of not being a Ruby 
programmer but a Ruby dabbler ;)

RJ

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Posted via http://www.ruby-forum.com/.

RurouniJones wrote:
> Hi all.
> 
> I am currently thinking about how to do the following:
> 
> I have the following models.
> Team
> Person
> 
> Team has various positions (manager, programmer etc.) I would like each 
> one of those positions to reference one or more Person records. A single 
> Person record could be on 6 different teams at the same time in 
> different roles. the same person could even be on the same team multiple 
> times in different roles.
> 
> I am not 100% sure how to go about this. I am thinking that I will need 
> something like an intermediate record.
> 
> teams_people
> id
> team_id
> people_id
> role
> 
> I would then have (I think) to have methods in the Team model that will 
> find each person in the @team.people array based on the role.
> 
> I the end I want a view to have something like:
> 
> Team Name
> Manager: Person1, Person 4
> Programmer: Person2, Person 3
> Designer: Person2
> Lackey: Person3
> 
> With just a single find that :includes all the relevant people.
You''re definitely on the right track. I''d suggest naming the
join model
something like Membership (table name ''memberships'' instead of
''teams_people''), which is the way to go when using has_many
:through
instead of habtm. Your use of the ''role'' field is exactly what
I''d do.
Here''s something I wrote that talks about working with this kind of
join
model and shows how you can use that to create convenient specialized 
accessors for the various roles:
http://blog.hasmanythrough.com/articles/2006/05/06/through_gets_uniq

I haven''t played around with using :include for that kind of setup, but
I think you should just be able to :include the various specialized 
associations and it will do the right thing.

--
Josh Susser
http://blog.hasmanythrough.com

-- 
Posted via http://www.ruby-forum.com/.

Josh Susser wrote:
> I haven''t played around with using :include for that kind of
setup, but
> I think you should just be able to :include the various specialized 
> associations and it will do the right thing.
> 
> --
> Josh Susser
> http://blog.hasmanythrough.com
Ye gods!

Thank you very much for the link. It is a stupendously good tutorial for 
this sort of thing. Thank you very much.

Do you have plans on adding that to the wiki.rubyonrails site? (Or 
create a page that then links to the blog?) I use the Wiki site 
extensively (as I imagine others do to) and a page that has this 
information would be great.

Many thanks

RJ

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