Hi all, Another newb online... trying belongs_to and has_one constructs for the first time. table Location defined as: nickname, street, city, ... , contact_id the model includes "belongs_to :contact" table Contact defined as: name, title, ... , location_id the model includes "has_one :location" When I build a list_contacts view, I assume h(contact.location.nickname) will make the connection. However Rails returns nil for contact.location. (Verified the linkage is present, thanks to script/console.) Seems like I''m missing something very simple, but I''m stumped. Ideas? Best, Brian Austin, Texas --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
bjpcjp-rphTv4pjVZMJGwgDXS7ZQA@public.gmane.org wrote:> > When I build a list_contacts view, I assume > h(contact.location.nickname) will make the connection. However Rails > returns nil for contact.location. (Verified the linkage is present, > thanks to script/console.) Seems like I''m missing something very > simple, but I''m stumped. Ideas? > > Best, > Brian > Austin, TexasCan you post your controller code for list_contacts? If you have ''dereferenced'' your scaffold code also make sure you have an instance variable that holds the information for your contact in the controller or else your view wont have anything to display. Also, maybe you just left this out, but contact.location is nil but is just contact nil also? Lastly, your table should be named w/ pluralizes names. Ex: ''create table Contacts ...'' and ''create table Locations...'' not the singular version you posted in your original mail. Remember models are singular and the db tables they are tied to are pluralized. I''ll assume that you posted just pseudo code but I had to mention it just in case. Hope this, at the least, kicks off a direction for a solution to your problem. -- 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 -~----------~----~----~----~------~----~------~--~---
You have 2 columns locations.contact_id and contacts.location_id. Of
these, only locations.contact_id is used by the associations you have
defined.
class Location < AR::Base
# This will lookup locations.contact_id to find the association
belongs_to :contact
end
class Contact < AR::Base
# This will also lookup locations.contact_id to find the association
has_one :location
end
Make sure that locations.contact_id is populated in your DB, and that
you haven''t mistakenly populated contacts.location_id instead.
BTW, if you need to query a list of contacts, think about the
performance of using associations.
Option 1:
contacts = Contact.find(:all)
# Each call to c.location triggers a DB query to delay load the
location for that contact
contacts.each { |c| c.location.nickname }
Option 2:
contacts = Contact.find(:all, :includes => [:location])
# All locations are loaded upfront, so there is only ever 1 DB call
contacts.each { |c| c.location.nickname }
Cheers,
Chris
On Jul 24, 3:02 pm, Jean Nibee
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:> bjp...-rphTv4pjVZMJGwgDXS7ZQA@public.gmane.org wrote:
>
> > When I build a list_contacts view, I assume
> > h(contact.location.nickname) will make the connection. However Rails
> > returns nil for contact.location. (Verified the linkage is present,
> > thanks to script/console.) Seems like I''m missing something
very
> > simple, but I''m stumped. Ideas?
>
> > Best,
> > Brian
> > Austin, Texas
>
> Can you post your controller code for list_contacts? If you have
> ''dereferenced'' your scaffold code also make sure you have
an instance
> variable that holds the information for your contact in the controller
> or else your view wont have anything to display.
>
> Also, maybe you just left this out, but contact.location is nil but is
> just contact nil also?
>
> Lastly, your table should be named w/ pluralizes names.
>
> Ex: ''create table Contacts ...'' and ''create
table Locations...'' not the
> singular version you posted in your original mail. Remember models are
> singular and the db tables they are tied to are pluralized.
>
> I''ll assume that you posted just pseudo code but I had to mention
it
> just in case.
>
> Hope this, at the least, kicks off a direction for a solution to your
> problem.
> --
> 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-/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 wrote:> > Option 1: > contacts = Contact.find(:all) > # Each call to c.location triggers a DB query to delay load the > location for that contact > contacts.each { |c| c.location.nickname } > > Option 2: > contacts = Contact.find(:all, :includes => [:location]) > # All locations are loaded upfront, so there is only ever 1 DB call > contacts.each { |c| c.location.nickname } > > Cheers, > Chris > > On Jul 24, 3:02 pm, Jean Nibee <rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>Adding to this, remove any DB calls in your view. this breaks the model / view/ controller architecture as you''re having a view interact directly WITH the Database. Encapsulate ALL ''business logic / use cases'' and database access in your controller and let your view determine how all the data ''sent'' to it is displayed. Even using a loop and querying the db for your location, although a minor infraction, is considered logic and not display. -- 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 -~----------~----~----~----~------~----~------~--~---