Find with has_many

Rails
1

I have a model Person and one Organisation. A Person can belong to any
number of Organisations and an Organisation can have any number of
Persons attributed to it. As below:

====
class Person < ActiveRecord::Base
has_many :person_organisations, :dependent => true
has_many :organisations, :through => :person_organisations
end

class Organisation < ActiveRecord::Base
has_many :person_organisations, :dependent => true
has_many :persons, :through => :person_organisations
end

I’m writing an action on my Person controller called
‘list_by_organisation’ which will return all the contacts from a
specified organisation. How do I achieve this?

Do I do something like the following? But what goes in the condition?

====
def list_by_organisation
@person_pages, @persons = paginate(:persons, :per_page => 20, :order
=> ‘id’, :conditions => [???])
render_action ‘list’
end

If I’m doing this in completely the wrong way then please do let me
know.

Thanks for any suggestions.

2

Matthew Planchant wrote:

class Organisation < ActiveRecord::Base

Thanks for any suggestions.

You need either has_and_belongs_to_many (if the join table has no
attributes), in which case you don’t need :through (AR does all that for
you), or if the join table has attributes (e.g. date of joining) you
need to declare that as a model (in which case I’d prob just call it
membership).

In your Person controller you could do something like @organisations =
Organisation.find(:all, :include => :persons) if you want all the
organisations, and then in your view iterate through them:

<% @organisations.each do |organisation| %>

<%= h(organisation.title) %>


organisation.persons.each do |person|

<%= h(person.name) %>


<% end %>
<% end %>

or if you just want members of a specific organisation (identified by,
say, params[:organisation_id])
@persons = Organisation.find(params[:organisation_id]).persons

Or something like that.

HTH
CT
p.s. I think rails by default uses people as the plural of persons (so
should be has_many :people, not has_many :persons, ditto all the other
persons)

3

You need either has_and_belongs_to_many (if the join table has no
attributes), in which case you don’t need :through (AR does all that for
you), or if the join table has attributes (e.g. date of joining) you
need to declare that as a model (in which case I’d prob just call it
membership).

Yep.

In your Person controller you could do something like @organisations =
Organisation.find(:all, :include => :persons) if you want all the
organisations, and then in your view iterate through them:

<% @organisations.each do |organisation| %>

<%= h(organisation.title) %>


organisation.persons.each do |person|

<%= h(person.name) %>


<% end %>
<% end %>

or if you just want members of a specific organisation (identified by,
say, params[:organisation_id])
@persons = Organisation.find(params[:organisation_id]).persons

Or something like that.

OK. Thanks.

So what is wrong with:

@person_pages, @people = paginate(:people, :per_page => 20, :order =>
‘id’, :include => :organisations, :conditions => [‘organisations.id=?’,
params[:id]])

p.s. I think rails by default uses people as the plural of persons (so
should be has_many :people, not has_many :persons, ditto all the other
persons)

Yep I’ve realised this. The above is just an example though.

4

Chris T wrote:

or if you just want members of a specific organisation (identified by,
say, params[:organisation_id])
@persons = Organisation.find(params[:organisation_id]).persons

That worked many thanks!