Rails - Dec 2007 - Using Models as Join Tables and/or Self Referential Joins?

Given a User model, I would like to describe a relationship between
two users and add additional information about the connection.  For
example, user A and B msg''d each other on X date, and are Y miles
apart.  In the book Agile Web Dev with Rails (pg 337), they describe
using models as join tables to add more information than foreign
keys.  However, join table models seems to only help describe
relationships if you have two models.

What do you use if you only have one User model and want to add
additional information about relationships between users?

I''ve googled through self referential joins, but most solutions only
outline simple relationship titles.  For example, user A is boss of
user B.  How would you add more information to this relationship in
one model?

Any advice is welcome, the solution need not be limited to one model.
--~--~---------~--~----~------------~-------~--~----~
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 19 Dec 2007, at 08:52, Chris wrote:
>
> Given a User model, I would like to describe a relationship between
> two users and add additional information about the connection.  For
> example, user A and B msg''d each other on X date, and are Y miles
> apart.  In the book Agile Web Dev with Rails (pg 337), they describe
> using models as join tables to add more information than foreign
> keys.  However, join table models seems to only help describe
> relationships if you have two models.
>
> What do you use if you only have one User model and want to add
> additional information about relationships between users?
>
See http://blog.hasmanythrough.com/2006/4/21/self-referential-through

Fred
> I''ve googled through self referential joins, but most solutions
only
> outline simple relationship titles.  For example, user A is boss of
> user B.  How would you add more information to this relationship in
> one model?
>
> Any advice is welcome, the solution need not be limited to one model.
> >

--~--~---------~--~----~------------~-------~--~----~
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 Dec 19, 2007, at 2:52 AM, Chris wrote:
>
> Given a User model, I would like to describe a relationship between
> two users and add additional information about the connection.  For
> example, user A and B msg''d each other on X date, and are Y miles
> apart.  In the book Agile Web Dev with Rails (pg 337), they describe
> using models as join tables to add more information than foreign
> keys.  However, join table models seems to only help describe
> relationships if you have two models.
>
> What do you use if you only have one User model and want to add
> additional information about relationships between users?
Do you really want to limit your message tracking to just one user  
per user?  In your example, if you''d have to have two fields,  
last_messaged_user_id and last_messaged_date on your User model.  So  
your two user records would look like:

id    name    last_messaged_user_id    last_messaged_date
1     A            2                                              
2007-12-19
2     B            1                                              
2007-12-19

You would never be able to track multiple messages this way.  A  
better design, if I understand your problem (which I doubt), is to  
use a join table and a has_many :through. The join table would have a  
from_user_id, a to_user_id, a date/time, and could even have the  
message, in which case, you could call it messages. Even if you don''t  
keep the message text here, my opinion is to not clutter up the user  
record with information not specifically related to the user.  This  
often results in over-normalization, in which case I sometimes have  
to denormalize some things, but I''d rather go that way than to have  
chaotic tables/models.

Peace,
Phillip


--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---

Wouldn''t you have a messages table (and therefore a messages table)
where
you would keep a from_id and a to_id representing both users, a message
field and a created_at field? Then from there you can get both the from and
the to user and work out how far apart they are. I''m assuming
you''re using
rails 2.0 here.

class Message
belongs_to :from, :class_name => "User"
belongs_to :to, :class_name => "User"
end




On Dec 20, 2007 12:02 AM, Phillip Koebbe
<phillipkoebbe-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
>
> On Dec 19, 2007, at 2:52 AM, Chris wrote:
>
> >
> > Given a User model, I would like to describe a relationship between
> > two users and add additional information about the connection.  For
> > example, user A and B msg''d each other on X date, and are Y
miles
> > apart.  In the book Agile Web Dev with Rails (pg 337), they describe
> > using models as join tables to add more information than foreign
> > keys.  However, join table models seems to only help describe
> > relationships if you have two models.
> >
> > What do you use if you only have one User model and want to add
> > additional information about relationships between users?
>
> Do you really want to limit your message tracking to just one user
> per user?  In your example, if you''d have to have two fields,
> last_messaged_user_id and last_messaged_date on your User model.  So
> your two user records would look like:
>
> id    name    last_messaged_user_id    last_messaged_date
> 1     A            2
> 2007-12-19
> 2     B            1
> 2007-12-19
>
> You would never be able to track multiple messages this way.  A
> better design, if I understand your problem (which I doubt), is to
> use a join table and a has_many :through. The join table would have a
> from_user_id, a to_user_id, a date/time, and could even have the
> message, in which case, you could call it messages. Even if you
don''t
> keep the message text here, my opinion is to not clutter up the user
> record with information not specifically related to the user.  This
> often results in over-normalization, in which case I sometimes have
> to denormalize some things, but I''d rather go that way than to
have
> chaotic tables/models.
>
> Peace,
> Phillip
>
>
> >
>

-- 
Ryan Bigg
http://www.frozenplague.net

--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---

Fred:  Thanks for the link, I came across that article after doing on
search on googletalk about self-referential models.  I wasn''t sure it
allowed for more than declaring simple relationships.  Over time, I
would like to add more information about the relationship, perhaps I
didn''t understand the article clearly -- I will take a look at it
again.

Phillip:  I believe you actually do sort of get what I''m trying to do,
and I''m just not thinking correctly about how the database should be
set up.  If I understand your post correctly, you recommend I add a
message model and then I can use a join table: message_user.  This
would be much better than self-referencing because even if I could
figure out a way to describe a relationship among users within a
single model, that information would clutter up in a single model
solution.

Ryan:  I think your solution is a better/simpler way of doing what I
am trying to accomplish.  Which leads me to a few other questions...

1. With a messages and users table I''m doing a 2 model w/ join table
solution, correct?  If this is the case, how would you keep track of
relationships among users, if messaging doesn''t equal having a
relationship?

2.  Also, any additional information about the relationship, say,
distance, level of correspondence, etc. that wouldn''t cleanly fit into
a messages model.  How would you go about organizing any  additional
relationship info.? Make a new model and join table between each User
model and (X Info) model?  (It''s obvious to me now that using only a
self-referential technique would lead to a massive and painfully slow
users table)

3.  I''m still on rails 1.2 and learning through the classic agile
dev.  Is it worth upgrading to 2.0 now? I don''t need to be bleeding
edge, and still learning the basics.

Chris
--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---

I think I''m sort of seeing what you are trying to do.  I would  
probably have a users table/model, a messages table/model, and a  
relationships table/model:

users have_many relationships
users have_many messages

relationships have_many users
messages have_many users

The relationships table would link the users together, and on that  
table you store the information specific to the relationship  
(distance, level of correspondence, etc).  One user can be part of  
many relationships.

The messages table would be an instance of a message between two  
users and could have from_user, to_user, sent_at, subject, body,  
parent_message_id (for threading/replies).

Peace,
Phillip

On Dec 19, 2007, at 7:31 PM, Chris wrote:
>
> Fred:  Thanks for the link, I came across that article after doing on
> search on googletalk about self-referential models.  I wasn''t sure
it
> allowed for more than declaring simple relationships.  Over time, I
> would like to add more information about the relationship, perhaps I
> didn''t understand the article clearly -- I will take a look at it
> again.
>
> Phillip:  I believe you actually do sort of get what I''m trying to
do,
> and I''m just not thinking correctly about how the database should
be
> set up.  If I understand your post correctly, you recommend I add a
> message model and then I can use a join table: message_user.  This
> would be much better than self-referencing because even if I could
> figure out a way to describe a relationship among users within a
> single model, that information would clutter up in a single model
> solution.
>
> Ryan:  I think your solution is a better/simpler way of doing what I
> am trying to accomplish.  Which leads me to a few other questions...
>
> 1. With a messages and users table I''m doing a 2 model w/ join
table
> solution, correct?  If this is the case, how would you keep track of
> relationships among users, if messaging doesn''t equal having a
> relationship?
>
> 2.  Also, any additional information about the relationship, say,
> distance, level of correspondence, etc. that wouldn''t cleanly fit
into
> a messages model.  How would you go about organizing any  additional
> relationship info.? Make a new model and join table between each User
> model and (X Info) model?  (It''s obvious to me now that using only
a
> self-referential technique would lead to a massive and painfully slow
> users table)
>
> 3.  I''m still on rails 1.2 and learning through the classic agile
> dev.  Is it worth upgrading to 2.0 now? I don''t need to be
bleeding
> edge, and still learning the basics.
>
--~--~---------~--~----~------------~-------~--~----~
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 Dec 20, 2007 12:01 PM, Chris
<mousepad-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> Ryan:  I think your solution is a better/simpler way of doing what I
> am trying to accomplish.  Which leads me to a few other questions...
>
> 1. With a messages and users table I''m doing a 2 model w/ join
table
> solution, correct?  If this is the case, how would you keep track of
> relationships among users, if messaging doesn''t equal having a
> relationship?
>
You''re doing two tables, users & messages, The messages table has
two fields
that link it to the users table. These are from_id and to_id. I''m
guessing
the last question in that point is that you want to see how many times a
user has messaged another user. Unfortunately there''s no easy way to go
about this. You would do a find on the Message model looking for all
messages that a user has sent to another user. Something like
Message.find_by_from_id_and_to_id(from,to).

>
> 2.  Also, any additional information about the relationship, say,
> distance, level of correspondence, etc. that wouldn''t cleanly fit
into
> a messages model.  How would you go about organizing any  additional
> relationship info.? Make a new model and join table between each User
> model and (X Info) model?  (It''s obvious to me now that using only
a
> self-referential technique would lead to a massive and painfully slow
> users table)
>
   This can be worked out on the fly when needed I guess. It''s not
processor
intensive (is it?).
>
>
> 3.  I''m still on rails 1.2 and learning through the classic agile
> dev.  Is it worth upgrading to 2.0 now? I don''t need to be
bleeding
> edge, and still learning the basics.
>
>
Upgrading is advisable.
-- 
Ryan Bigg
http://www.frozenplague.net

--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---

Phillip: That sounds great, I have a clear understanding of the next
steps to implement.  About the relationship model though, it will have
two foreign keys (one for each user) along with a few other useful
columns.  Even though it will always be 2 users to a relationship, we
would still consider it a many-to-many relationship (users table and
relationship table), thus requiring a join table relationships_users
and messages_users?
--~--~---------~--~----~------------~-------~--~----~
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 Dec 19, 2007, at 8:50 PM, Chris Shen wrote:
>
> Phillip: That sounds great, I have a clear understanding of the next
> steps to implement.  About the relationship model though, it will have
> two foreign keys (one for each user) along with a few other useful
> columns.  Even though it will always be 2 users to a relationship, we
> would still consider it a many-to-many relationship (users table and
> relationship table), thus requiring a join table relationships_users
> and messages_users?
>
Well, let me ask you this:  Can User A be in only one relationship at  
a time?  So if User A is in a relationship with User B, User C is out  
in the cold until User D comes along?  If that''s true, then no, you  
don''t need a many to many.  But I was going on the assumption that  
User A could have simultaneous relationships with any number of other  
users, in which case you need a many to many. Unless there is a gap  
in my knowledge, which there often is.

Phillip

--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---

Phillip:  Haha, no you''re assumption is correct.  Thanks for all your
help.

Ryan: I''ll take a look at upgrading when I can find a good milestone
to stop at on my current project.  Have your heard of any projects in
development breaking after upgrading to the recent 2.0?
--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---

Nope. Rails 2.0 is designed to be as stable or even more stable than
previous versions.

On Dec 20, 2007 2:37 PM, Chris Shen
<mousepad-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> Phillip:  Haha, no you''re assumption is correct.  Thanks for all
your
> help.
>
> Ryan: I''ll take a look at upgrading when I can find a good
milestone
> to stop at on my current project.  Have your heard of any projects in
> development breaking after upgrading to the recent 2.0?
> >
>

-- 
Ryan Bigg
http://www.frozenplague.net

--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---

Ran into a wall when trying to implement a n-to-n relationship between
two models: User and Relationship.  One user can have multiple
relationships with other users.  One relationship has two users.

My models:

class Relationship < ActiveRecord::Base
  has_many :relationships_users
  has_many :users, :through => :users_relationships
end

class User < ActiveRecord::Base
  has_many :relationships_users
  has_many :relationships, :through => :users_relationships
end



My migration:

class CreateRelationships < ActiveRecord::Migration
  def self.up
    create_table :relationships do |t|
      t.column :person1, :integer
      t.column :person2, :integer
      t.column :created_at, :datetime
    end

    create_table :users_relationships, :id => false do |t|
      t.column :user_id, :integer
      t.column :relationship_id, :integer
    end
   ...
end


I am currently able to have users populate the relationships table so
it fills with user_id''s in the person1&2 columns; relationship
established.  But I can''t figure out how to utilize the connections
I''ve formed in rails to make calls like:

# I have no idea if the code below is the proper way to go about this

user = Relationship.find_all_by_person1("35")  # This should find all
rows where user_id 35 appears in the person1 column and returns an
array??
relationship_user1 = User.find_by_id(user)
relationship_user1.display_photo

In other words, I know which two users are paired, but how do I pull
information out of the User model through the relationship table? I''ve
spent the whole day reading through all the explanations on the
internet on this topic, so please no links.  I''m having great
difficulty understanding the theoretical syntax to traverse through
these relationships.


--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---

Blargh!

has_and_belongs_to_many is your friend. Please show him/her/it some respect.

On Dec 21, 2007 5:14 PM, Chris Shen
<mousepad-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> Ran into a wall when trying to implement a n-to-n relationship between
> two models: User and Relationship.  One user can have multiple
> relationships with other users.  One relationship has two users.
>
> My models:
>
> class Relationship < ActiveRecord::Base
>  has_many :relationships_users
>  has_many :users, :through => :users_relationships
> end
>
> class User < ActiveRecord::Base
>  has_many :relationships_users
>  has_many :relationships, :through => :users_relationships
> end
>
>
>
> My migration:
>
> class CreateRelationships < ActiveRecord::Migration
>  def self.up
>    create_table :relationships do |t|
>      t.column :person1, :integer
>      t.column :person2, :integer
>      t.column :created_at, :datetime
>    end
>
>    create_table :users_relationships, :id => false do |t|
>      t.column :user_id, :integer
>      t.column :relationship_id, :integer
>    end
>   ...
> end
>
>
> I am currently able to have users populate the relationships table so
> it fills with user_id''s in the person1&2 columns; relationship
> established.  But I can''t figure out how to utilize the
connections
> I''ve formed in rails to make calls like:
>
> # I have no idea if the code below is the proper way to go about this
>
> user = Relationship.find_all_by_person1("35")  # This should find
all
> rows where user_id 35 appears in the person1 column and returns an
> array??
> relationship_user1 = User.find_by_id(user)
> relationship_user1.display_photo
>
> In other words, I know which two users are paired, but how do I pull
> information out of the User model through the relationship table?
I''ve
> spent the whole day reading through all the explanations on the
> internet on this topic, so please no links.  I''m having great
> difficulty understanding the theoretical syntax to traverse through
> these relationships.
>
>
> >
>

-- 
Ryan Bigg
http://www.frozenplague.net

--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---

Ok cool, if I use habtm what will the syntax look like to call a user
method from the relationship table?

--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---

The current models does not make much sense. Without the requirements  
it is not possible to help

Sent from my iPhone

On Dec 20, 2007, at 10:44 PM, Chris Shen
<mousepad-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> Ran into a wall when trying to implement a n-to-n relationship between
> two models: User and Relationship.  One user can have multiple
> relationships with other users.  One relationship has two users.
>
> My models:
>
> class Relationship < ActiveRecord::Base
>  has_many :relationships_users
>  has_many :users, :through => :users_relationships
> end
>
> class User < ActiveRecord::Base
>  has_many :relationships_users
>  has_many :relationships, :through => :users_relationships
> end
>
>
>
> My migration:
>
> class CreateRelationships < ActiveRecord::Migration
>  def self.up
>    create_table :relationships do |t|
>      t.column :person1, :integer
>      t.column :person2, :integer
>      t.column :created_at, :datetime
>    end
>
>    create_table :users_relationships, :id => false do |t|
>      t.column :user_id, :integer
>      t.column :relationship_id, :integer
>    end
>   ...
> end
>
>
> I am currently able to have users populate the relationships table so
> it fills with user_id''s in the person1&2 columns; relationship
> established.  But I can''t figure out how to utilize the
connections
> I''ve formed in rails to make calls like:
>
> # I have no idea if the code below is the proper way to go about this
>
> user = Relationship.find_all_by_person1("35")  # This should find
all
> rows where user_id 35 appears in the person1 column and returns an
> array??
> relationship_user1 = User.find_by_id(user)
> relationship_user1.display_photo
>
> In other words, I know which two users are paired, but how do I pull
> information out of the User model through the relationship table?
I''ve
> spent the whole day reading through all the explanations on the
> internet on this topic, so please no links.  I''m having great
> difficulty understanding the theoretical syntax to traverse through
> these relationships.
>
>
> >
--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---

your migration don''t look correct then using through you should not
use:
create_table :users_relationships, :id => false do |t|
just use
create_table :relationships_users

regards
svend

On Dec 21, 9:56 am, Bcp <bcpar...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> The current models does not make much sense. Without the requirements
> it is not possible to help
>
> Sent from my iPhone
>
> On Dec 20, 2007, at 10:44 PM, Chris Shen
<mouse...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> > Ran into a wall when trying to implement a n-to-n relationship between
> > two models: User and Relationship.  One user can have multiple
> > relationships with other users.  One relationship has two users.
>
> > My models:
>
> > class Relationship < ActiveRecord::Base
> >  has_many :relationships_users
> >  has_many :users, :through => :users_relationships
> > end
>
> > class User < ActiveRecord::Base
> >  has_many :relationships_users
> >  has_many :relationships, :through => :users_relationships
> > end
>
> > My migration:
>
> > class CreateRelationships < ActiveRecord::Migration
> >  def self.up
> >    create_table :relationships do |t|
> >      t.column :person1, :integer
> >      t.column :person2, :integer
> >      t.column :created_at, :datetime
> >    end
>
> >    create_table :users_relationships, :id => false do |t|
> >      t.column :user_id, :integer
> >      t.column :relationship_id, :integer
> >    end
> >   ...
> > end
>
> > I am currently able to have users populate the relationships table so
> > it fills with user_id''s in the person1&2 columns;
relationship
> > established.  But I can''t figure out how to utilize the
connections
> > I''ve formed in rails to make calls like:
>
> > # I have no idea if the code below is the proper way to go about this
>
> > user = Relationship.find_all_by_person1("35")  # This should
find all
> > rows where user_id 35 appears in the person1 column and returns an
> > array??
> > relationship_user1 = User.find_by_id(user)
> > relationship_user1.display_photo
>
> > In other words, I know which two users are paired, but how do I pull
> > information out of the User model through the relationship table?
I''ve
> > spent the whole day reading through all the explanations on the
> > internet on this topic, so please no links.  I''m having great
> > difficulty understanding the theoretical syntax to traverse through
> > these relationships.
--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---

bcp: My apologies, for not stating my goals clearly.  I am trying to
keep track of relationships among users with a users table and
relationships table.  The requirements are that there can only be two
users in one relationship and I should be able to retrieve information
about each user in a relationship given a relationship_id.  I am
trying to accomplish this with the models I''ve written.

gundestrup: I think you''re right, I''ve tried implementing
habtm and
through relationships at the same time and end up not being able to do
either.  Thanks for catching that.  I''ve removed the :through in each
of my models and they are now all has_and_belongs_to_many in the User
and Relationship models, which justifies the :id => false, me
thinks.   In any case, can you describe what the CRUD syntax will be
if I''m using habtm or through relationships to retrieve data from the
users table?
--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---

#1. What is the person1, person2 columns?
#2. What are the concepts in your domain?
#3. What is the use case?

It seems to me your current models are not having the right attributes or
you are missing a key abstraction in your domain.
On Dec 21, 2007 12:29 PM, Chris Shen
<mousepad-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> bcp: My apologies, for not stating my goals clearly.  I am trying to
>
>
--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---

Just replied to another mail doing something very similar, and I have no
idea if it''ll work, but you could try:

class User < ActiveRecord::Base
has_and_belongs_to_many :relationships, :foreign_key => "from_id"
has_and_belongs_to_many :related_with, :table_name =>
"relationships_users",
:foreign_key => "to_id"
end



On Dec 22, 2007 7:17 AM, Bala Paranj
<bcparanj-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> #1. What is the person1, person2 columns?
> #2. What are the concepts in your domain?
> #3. What is the use case?
>
> It seems to me your current models are not having the right attributes or
> you are missing a key abstraction in your domain.
> On Dec 21, 2007 12:29 PM, Chris Shen
<mousepad-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> >
> > bcp: My apologies, for not stating my goals clearly.  I am trying to
> >
> >
> >
>

-- 
Ryan Bigg
http://www.frozenplague.net

--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---