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 =
‘Paran’”).id,
nome: ‘Cianorte’)
City.create!(country_id: Country.find(:first, conditions: “sigla =
‘BR’”).id,
state_id: State.find(:first, conditions: “nome = ‘So
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| %>
<%= f.label :cidade %> <%= f.collection_select :city_id, @cities, :id, :nome, include_blank: true %> (to be included later)
State index template:
Selecione um estado
| <%= s.sigla %> | <%= s.nome %> | <%= button_to 'Selecionar', institution_selstate_path( s ) %> |
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
.