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LuisRuby

2012-May-28 03:37 UTC

How to load a selection list into the method new of a controller?

Hi friends!
I''m relatively new with Rails and I''m struggling for a long
time with this
problem (it should have a pattern solution but until now I didn''t find
it):
I have the following models: Institution, City, State and Country.

class Country < ActiveRecord::Base
  has_many :states
  has_many :cities, :through => :states
end
# == Schema Information
# Table name: countries
#  id         :integer         not null, primary key
#  sigla      :string(2)       not null
#  nome       :string(30)      not null

class State < ActiveRecord::Base
  has_many   :cities
  has_many   :institutions, :through => :cities
  belongs_to :country
end
# == Schema Information
# Table name: states
#  id         :integer         not null, primary key
#  country_id :integer     not null
#  sigla      :string(2)      not null
#  nome       :string(40)  not null

class City < ActiveRecord::Base
  has_many :institutions
  belongs_to :country
  belongs_to :state
end
# == Schema Information
# Table name: cities
#  id          :integer         not null, primary key
#  country_id  :integer         not null
#  state_id    :integer         not null
#  nome        :string(40)      not null

class Institution < ActiveRecord::Base
  belongs_to :city
end
# == Schema Information
# Table name: institutions
#  id                 :integer         not null, primary key
#  city_id            :integer

The table states is pre-loaded with all Brazil''s states (seed):

State.create!(country_id: Country.find(:first, conditions: "sigla = 
''ZZ''").id, nome: ''desconhecido'', sigla:
''ZZ'')
State.create!(country_id: Country.find(:first, conditions: "sigla = 
''BR''").id, nome: ''Distrito Federal'',
sigla: ''DF'')
State.create!(country_id: Country.find(:first, conditions: "sigla = 
''BR''").id, nome: ''Acre'', sigla:
''AC'') ... and so on...
City.create!(country_id: Country.find(:first, conditions: "sigla = 
''BR''").id,
             state_id: State.find(:first, conditions: "nome = 
''desconhecido''").id,
             nome: ''desconhecida'')
City.create!(country_id: Country.find(:first, conditions: "sigla = 
''BR''").id,
             state_id: State.find(:first, conditions: "nome =
''Paraná''").id,
             nome: ''Cianorte'')
City.create!(country_id: Country.find(:first, conditions: "sigla = 
''BR''").id,
             state_id: State.find(:first, conditions: "nome = ''São
Paulo''").id,
             nome: ''Campinas'') ... and so on...

 When I create a new institution, I have to select a city from a drop-down 
list. But I need to constrain this list with the state the cities belong 
to. So I tried this way:

routes.rb:
Application.routes.draw do
  get "states/index"
  resources :institutions do
    post ''selstate''
  end
  resources :cities
  resources :states, only: :index

rake routes:
          states_index GET    
/states/index(.:format)                                      states#index
institution_selstate POST   
/institutions/:institution_id/selstate(.:format)        
institutions#selstate
             institutions GET    /institutions(.:format)            
                             institutions#index
                            POST   /institutions(.:format)              
                           institutions#create
       new_institution GET    /institutions/new(.:format)         
                         institutions#new

Institution new template:
<%= form_for(@institution) do |f| %>
  <fieldset>
  <legend>Cidade onde se localiza a instituição</legend>
    <div class="field">
      Estado selecionado:
      <%= @estado_selecionado %>
      <%= link_to "Selecionar estado...", states_path %><br
/>
      <%= f.label :cidade %>
      <%= f.collection_select :city_id, @cities, :id, :nome, include_blank: 
true %>
      <!--%#= link_to "Incluir nova cidade", new_city_path %-->
(to be
included later)
    </div>
<% end %>
  </fieldset>

State index template:
<h3>Selecione um estado</h3>
<table>
  <% @states.each do |s| %>
    <tr>
      <td><%= s.sigla %></td>
      <td><%= s.nome %></td>
      <td><%= button_to ''Selecionar'',
institution_selstate_path( s ) %></td>
    </tr>
  <% end %>
</table>

class StatesController < ApplicationController
  def index
    @states = State.where(''nome != ?'',
''desconhecido'').order(:nome)
  end

class InstitutionsController < ApplicationController
  def new
    @institution = Institution.new
    if session[:state_id].nil?
      session[:state_id] = State.find_by_sigla(''ZZ'').id
    end
    @estado_selecionado = State.find(session[:state_id]).nome
    if @estado_selecionado == ''desconhecido''
      @cities = City.all
    else
      @cities = City.where(''state_id = ?'',
session[:state_id]).order(:nome)
    end
    respond_to do |format| ...
    end
  end

  def create
    @institution = Institution.new(params[:institution])
    respond_to do |format|
      if @institution.save ...
    end

  def selstate
    session[:state_id] = params[:id]
    redirect_to new_institution_path
  end
 end

As you can see, after select the state, I return to the Institution new 
action. My hope was to have a state selected and the cities list 
constrained to those pertaining to that state. But nothing happens. I 
receive the same screen before the state selection. I have many similar 
situations in my system... all waiting for this solution  :-) .
Is my approach correct?
Any help will be very appreciated. Sorry my bad english!
Thanks in advance!

Luis

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Colin Law

2012-May-28 06:27 UTC

head link

Re: How to load a selection list into the method new of a controller?

On 28 May 2012 04:37, LuisRuby
<alfamemoria-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Hi friends!
> I''m relatively new with Rails and I''m struggling for a
long time with this
> problem (it should have a pattern solution but until now I didn''t
find it):
> I have the following models: Institution, City, State and Country.
>
> class Country < ActiveRecord::Base
>   has_many :states
>   has_many :cities, :through => :states
> end
> # == Schema Information
> # Table name: countries
> #  id         :integer         not null, primary key
> #  sigla      :string(2)       not null
> #  nome       :string(30)      not null
>
> class State < ActiveRecord::Base
>   has_many   :cities
>   has_many   :institutions, :through => :cities
>   belongs_to :country
> end
> # == Schema Information
> # Table name: states
> #  id         :integer         not null, primary key
> #  country_id :integer     not null
> #  sigla      :string(2)      not null
> #  nome       :string(40)  not null
>
> class City < ActiveRecord::Base
>   has_many :institutions
>   belongs_to :country
That is not right, a cities country is accessible through the state
via @city.state.country.
>   belongs_to :state
> end
> # == Schema Information
> # Table name: cities
> #  id          :integer         not null, primary key
> #  country_id  :integer         not null
Above is not needed.

I have not even read the rest, you have provided much too much
information.  If you still have a problem then simplify it down to to
the smallest amount of code that demonstrates it and post that.

Colin
> #  state_id    :integer         not null
> #  nome        :string(40)      not null
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LuisRuby

2012-May-28 12:58 UTC

head link

Re: How to load a selection list into the method new of a controller?

Thank you for your fast reply!
Yes, I agree it isn''t necessary to put a direct relation to country
inside
the city model. But I did it because sometimes the user will not know to 
which state a new city belongs to, and at least he will know the country.

Luis

Em segunda-feira, 28 de maio de 2012 03h27min39s UTC-3, Colin Law
escreveu:>
> On 28 May 2012 04:37, LuisRuby wrote: 
> > Hi friends! 
> > I''m relatively new with Rails and I''m struggling for
a long time with
> this 
> > problem (it should have a pattern solution but until now I
didn''t find
> it): 
> > I have the following models: Institution, City, State and Country. 
> > 
> > class Country < ActiveRecord::Base 
> >   has_many :states 
> >   has_many :cities, :through => :states 
> > end 
> > # == Schema Information 
> > # Table name: countries 
> > #  id         :integer         not null, primary key 
> > #  sigla      :string(2)       not null 
> > #  nome       :string(30)      not null 
> > 
> > class State < ActiveRecord::Base 
> >   has_many   :cities 
> >   has_many   :institutions, :through => :cities 
> >   belongs_to :country 
> > end 
> > # == Schema Information 
> > # Table name: states 
> > #  id         :integer         not null, primary key 
> > #  country_id :integer     not null 
> > #  sigla      :string(2)      not null 
> > #  nome       :string(40)  not null 
> > 
> > class City < ActiveRecord::Base 
> >   has_many :institutions 
> >   belongs_to :country 
>
> That is not right, a cities country is accessible through the state 
> via @city.state.country. 
>
> >   belongs_to :state 
> > end 
> > # == Schema Information 
> > # Table name: cities 
> > #  id          :integer         not null, primary key 
> > #  country_id  :integer         not null 
>
> Above is not needed. 
>
> I have not even read the rest, you have provided much too much 
> information.  If you still have a problem then simplify it down to to 
> the smallest amount of code that demonstrates it and post that. 
>
> Colin 
>
> > #  state_id    :integer         not null 
> > #  nome        :string(40)      not null 
>
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Colin Law

2012-May-28 19:49 UTC

head link

Re: How to load a selection list into the method new of a controller?

On 28 May 2012 13:58, LuisRuby
<alfamemoria-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Thank you for your fast reply!
> Yes, I agree it isn''t necessary to put a direct relation to
country inside
> the city model. But I did it because sometimes the user will not know to
> which state a new city belongs to, and at least he will know the country.
With it in you could get into a situation where @city.country is not
the same as @city.state.country.  Also note that @country.cities will
only include those accessed via state.

Please don''t top post, it makes it difficult to follow the thread.
Insert you reply at appropriate points in the previous message.
Thanks.

Colin
>
> Luis
>
> Em segunda-feira, 28 de maio de 2012 03h27min39s UTC-3, Colin Law escreveu:
>>
>> On 28 May 2012 04:37, LuisRuby wrote:
>> > Hi friends!
>> > I''m relatively new with Rails and I''m struggling
for a long time with
>> > this
>> > problem (it should have a pattern solution but until now I
didn''t find
>> > it):
>> > I have the following models: Institution, City, State and Country.
>> >
>> > class Country < ActiveRecord::Base
>> >   has_many :states
>> >   has_many :cities, :through => :states
>> > end
>> > # == Schema Information
>> > # Table name: countries
>> > #  id         :integer         not null, primary key
>> > #  sigla      :string(2)       not null
>> > #  nome       :string(30)      not null
>> >
>> > class State < ActiveRecord::Base
>> >   has_many   :cities
>> >   has_many   :institutions, :through => :cities
>> >   belongs_to :country
>> > end
>> > # == Schema Information
>> > # Table name: states
>> > #  id         :integer         not null, primary key
>> > #  country_id :integer     not null
>> > #  sigla      :string(2)      not null
>> > #  nome       :string(40)  not null
>> >
>> > class City < ActiveRecord::Base
>> >   has_many :institutions
>> >   belongs_to :country
>>
>> That is not right, a cities country is accessible through the state
>> via @city.state.country.
>>
>> >   belongs_to :state
>> > end
>> > # == Schema Information
>> > # Table name: cities
>> > #  id          :integer         not null, primary key
>> > #  country_id  :integer         not null
>>
>> Above is not needed.
>>
>> I have not even read the rest, you have provided much too much
>> information.  If you still have a problem then simplify it down to to
>> the smallest amount of code that demonstrates it and post that.
>>
>> Colin
>>
>> > #  state_id    :integer         not null
>> > #  nome        :string(40)      not null
>
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>
> To post to this group, send email to
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>
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LuisRuby

2012-May-28 22:31 UTC

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Re: How to load a selection list into the method new of a controller?

Em segunda-feira, 28 de maio de 2012 00h37min14s UTC-3, LuisRuby
escreveu:>
> Hi friends!
> I''m relatively new with Rails and I''m struggling for a
long time with this
> problem (it should have a pattern solution but until now I didn''t
find it):
> I have the following models: Institution, City, State and Country.
>
> class Country < ActiveRecord::Base
>   has_many :states
>   has_many :cities, :through => :states
> end
> # == Schema Information
> # Table name: countries
> #  id         :integer         not null, primary key
> #  sigla      :string(2)       not null
> #  nome       :string(30)      not null
>
> class State < ActiveRecord::Base
>   has_many   :cities
>   has_many   :institutions, :through => :cities
>   belongs_to :country
> end
> # == Schema Information
> # Table name: states
> #  id         :integer         not null, primary key
> #  country_id :integer     not null
> #  sigla      :string(2)      not null
> #  nome       :string(40)  not null
>
> class City < ActiveRecord::Base
>   has_many :institutions
>   belongs_to :country
>   belongs_to :state
> end
> # == Schema Information
> # Table name: cities
> #  id          :integer         not null, primary key
> #  country_id  :integer         not null
> #  state_id    :integer         not null
> #  nome        :string(40)      not null
>
> class Institution < ActiveRecord::Base
>   belongs_to :city
> end
> # == Schema Information
> # Table name: institutions
> #  id                 :integer         not null, primary key
> #  city_id            :integer
>
> The table states is pre-loaded with all Brazil''s states (seed):
>
> State.create!(country_id: Country.find(:first, conditions: "sigla = 
> ''ZZ''").id, nome: ''desconhecido'',
sigla: ''ZZ'')
> State.create!(country_id: Country.find(:first, conditions: "sigla = 
> ''BR''").id, nome: ''Distrito
Federal'', sigla: ''DF'')
> State.create!(country_id: Country.find(:first, conditions: "sigla = 
> ''BR''").id, nome: ''Acre'', sigla:
''AC'') ... and so on...
> City.create!(country_id: Country.find(:first, conditions: "sigla = 
> ''BR''").id,
>              state_id: State.find(:first, conditions: "nome = 
> ''desconhecido''").id,
>              nome: ''desconhecida'')
> City.create!(country_id: Country.find(:first, conditions: "sigla = 
> ''BR''").id,
>              state_id: State.find(:first, conditions: "nome = 
> ''Paraná''").id,
>              nome: ''Cianorte'')
> City.create!(country_id: Country.find(:first, conditions: "sigla = 
> ''BR''").id,
>              state_id: State.find(:first, conditions: "nome =
''São
> Paulo''").id,
>              nome: ''Campinas'') ... and so on...
>
>  When I create a new institution, I have to select a city from a drop-down 
> list. But I need to constrain this list with the state the cities belong 
> to. So I tried this way:
>
> routes.rb:
> Application.routes.draw do
>   get "states/index"
>   resources :institutions do
>     post ''selstate''
>   end
>   resources :cities
>   resources :states, only: :index
>
> rake routes:
>           states_index GET    
> /states/index(.:format)                                      states#index
> institution_selstate POST   
> /institutions/:institution_id/selstate(.:format)        
> institutions#selstate
>              institutions GET    /institutions(.:format)            
>                              institutions#index
>                             POST   /institutions(.:format)              
>                            institutions#create
>        new_institution GET    /institutions/new(.:format)         
>                          institutions#new
>
> Institution new template:
> <%= form_for(@institution) do |f| %>
>   <fieldset>
>   <legend>Cidade onde se localiza a instituição</legend>
>     <div class="field">
>       Estado selecionado:
>       <%= @estado_selecionado %>
>       <%= link_to "Selecionar estado...", states_path
%><br />
>       <%= f.label :cidade %>
>       <%= f.collection_select :city_id, @cities, :id, :nome, 
> include_blank: true %>
>       <!--%#= link_to "Incluir nova cidade", new_city_path
%--> (to be
> included later)
>     </div>
> <% end %>
>   </fieldset>
>
> State index template:
> <h3>Selecione um estado</h3>
> <table>
>   <% @states.each do |s| %>
>     <tr>
>       <td><%= s.sigla %></td>
>       <td><%= s.nome %></td>
>       <td><%= button_to ''Selecionar'',
institution_selstate_path( s )
> %></td>
>     </tr>
>   <% end %>
> </table>
>
> class StatesController < ApplicationController
>   def index
>     @states = State.where(''nome != ?'',
''desconhecido'').order(:nome)
>   end
>
> class InstitutionsController < ApplicationController
>   def new
>     @institution = Institution.new
>     if session[:state_id].nil?
>       session[:state_id] = State.find_by_sigla(''ZZ'').id
>     end
>     @estado_selecionado = State.find(session[:state_id]).nome
>     if @estado_selecionado == ''desconhecido''
>       @cities = City.all
>     else
>       @cities = City.where(''state_id = ?'',
session[:state_id]).order(:nome)
>     end
>     respond_to do |format| ...
>     end
>   end
>
>   def create
>     @institution = Institution.new(params[:institution])
>     respond_to do |format|
>       if @institution.save ...
>     end
>
>   def selstate
>     session[:state_id] = params[:id]
>     redirect_to new_institution_path
>   end
>  end
>
> As you can see, after select the state, I return to the Institution new 
> action. My hope was to have a state selected and the cities list 
> constrained to those pertaining to that state. But nothing happens. I 
> receive the same screen before the state selection. I have many similar 
> situations in my system... all waiting for this solution  :-) .
> Is my approach correct?
> Any help will be very appreciated. Sorry my bad english!
> Thanks in advance!
>
> Luis
>
Hmmmm, I didn''t think in this situation... you are right. I will
exclude
country_id from de city model. 
Well. Filtering my models to simplify the explanation of my problem, I end 
up with these:

class State < ActiveRecord::Base
  has_many   :cities
  has_many   :institutions, :through => :cities
  belongs_to :country
end

class City < ActiveRecord::Base
  has_many :institutions
  belongs_to :state
end

class Institution < ActiveRecord::Base
  belongs_to :city
end

The table states is pre-loaded with all Brazil''s states (seed):

State.create!(country_id: Country.find(:first, conditions: "sigla = 
''ZZ''").id, nome: ''desconhecido'', sigla:
''ZZ'')
State.create!(country_id: Country.find(:first, conditions: "sigla = 
''BR''").id, nome: ''Distrito Federal'',
sigla: ''DF'')
State.create!(country_id: Country.find(:first, conditions: "sigla = 
''BR''").id, nome: ''Acre'', sigla:
''AC'') ... and so on...
City.create!(state_id: State.find(:first, conditions: "nome = 
''desconhecido''").id, nome:
''desconhecida'')
City.create!(state_id: State.find(:first, conditions: "nome = 
''Paraná''").id, nome: ''Cianorte'')
City.create!(state_id: State.find(:first, conditions: "nome = ''São
Paulo''").id, nome: ''Campinas'') ... and so on...

 When I create a new institution, I have to select a city from a drop-down 
list. But I need to constrain this list with the state the cities belong 
to. So I tried this way:

routes.rb:
Application.routes.draw do
  get ''states/index''
  resources :institutions do
    post ''selstate''
  end
  resources :cities

rake routes:
          states_index GET    /states/index(.:format)       
                               states#index
institution_selstate POST   
/institutions/:institution_id/selstate(.:format)        
institutions#selstate
             institutions GET    /institutions(.:format)            
                             institutions#index
                            POST   /institutions(.:format)              
                           institutions#create
       new_institution GET    /institutions/new(.:format)         
                         institutions#new

Institution new template:
<%= form_for(@institution) do |f| %>
    <div class="field">
      Estado selecionado: <%= @estado_selecionado %>
      <%= link_to "Selecionar estado...", states_path %><br
/>
      <%= f.label :cidade %>
      <%= f.collection_select :city_id, @cities, :id, :nome, include_blank: 
true %>
    </div>
<% end %>

State index template:
<h3>Selecione um estado</h3>
<table>
  <% @states.each do |s| %>
    <tr>
      <td><%= s.sigla %></td>
      <td><%= s.nome %></td>
      <td><%= button_to ''Selecionar'',
institution_selstate_path( s ) %></td>
    </tr>
  <% end %>
</table>

class StatesController < ApplicationController
  def index
    @states = State.all
  end

class InstitutionsController < ApplicationController
  def new
    @institution = Institution.new
    if session[:state_id].nil?
      session[:state_id] = State.find_by_sigla(''ZZ'').id
    end
    @estado_selecionado = State.find(session[:state_id]).nome
    if @estado_selecionado == ''desconhecido''
      @cities = City.all
    else
      @cities = City.where(''state_id = ?'',
session[:state_id]).order(:nome)
    end
    respond_to do |format| ...
    end
  end

  def create
    @institution = Institution.new(params[:institution])
    respond_to do |format|
      if @institution.save ...
    end

  def selstate
    session[:state_id] = params[:id]
    redirect_to new_institution_path
  end
 end

As you can see, after select the state, I return to the Institution new 
action. My hope was to have a state selected and the cities list 
constrained to those pertaining to that state. But nothing happens. I 
receive the same screen before the state selection. Is my approach correct?
 
Thanks!
Luis

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