Hello,
I''m pretty new to Ruby on Rails (ROR) so I''m sorry if this is
a silly
thing to ask. I have tried looking at several tutorials online but
most of them are for the earlier version of ROR and even the API is
not helping me too much!
Basically I would like to create a drop down list in a form. I have
simplified my problem so that you''ll be able to understand it in a few
lines.
A simple diagram is here:
http://learningspirit.co.uk/class_diagram.png
The migration and model files are here:
## db/migrate/003_books.rb
class Books < ActiveRecord::Migration
def self.up
create_table :books do |t|
t.column :title, :string, :limit => 32, :null => false
t.column :price, :float
t.column :subject_id, :integer
t.column :description, :text
t.column :created_at, :timestamp
end
end
def self.down
drop_table :books
end
end
## db/migrate/004_subjects.rb
class Subjects < ActiveRecord::Migration
def self.up
create_table :subjects do |t|
t.column :name, :string
end
Subject.create :name => "Physics"
Subject.create :name => "Mathematics"
Subject.create :name => "Chemistry"
Subject.create :name => "Psychology"
Subject.create :name => "Geography"
end
def self.down
drop_table :subjects
end
end
## app/model/book.rb
class Book < ActiveRecord::Base
belongs_to :subject
validates_presence_of :title
validates_numericality_of :price, :message=>"Error message"
end
## app/model/subject.rb
class Subject < ActiveRecord::Base
has_many :books
end
The relevant book_controller.rb methods are:
def new
@book = Book.new
@subjects = Subject.find(:all)
end
def create
@book = Book.new(params[:book])
if @book.save
redirect_to :action => ''list''
else
@subjects = Subject.find(:all)
render :action => ''new''
end
end
The problem I have is in the view for the form to create a new book
entry. The view (app/views/book/new.html.erb) is looking like this at
the moment:
<h1>Add new book</h1>
<% form_for :book, @book, :url => { :action => "create" } do
|f| %>
<p>
<label>Title</label>:
<%= text_field @book, :title %>
</p>
<p>
<label>Price</label>:
<%= text_field @book, :price %>
</p>
<p>
<label>Subject</label>:
<%= collection_select :book, :subject_id, @subjects, :id, :name %>
</p>
<p>
<label>Description</label>:
<%= text_area @book, :description %>
</p>
<p>
<%= f.submit "Create"%>
</p>
<% end %>
<%= link_to ''Back'', {:action =>
''list''} %>
My problem is that I cannot get the drop down list to work! I have
tried select (instead of collection_sort) but I am always getting
errors. At the moment I have the following error:
undefined method `subject_id'' for #<Book id: nil, created_at: nil,
updated_at: nil>
I don''t understand this at all because from the documentation, there
should be a method there!
Please could some help me? What exactly are the arguments for the
collection_select method? What is wrong with my collection_select
call?
Thank you very much and I hope this wasn''t too long winded!
Inuka.
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On Jun 7, 1:33 am, nuky <inuk...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> > My problem is that I cannot get the drop down list to work! I have > tried select (instead of collection_sort) but I am always getting > errors. At the moment I have the following error: > > undefined method `subject_id'' for #<Book id: nil, created_at: nil, > updated_at: nil> > > I don''t understand this at all because from the documentation, there > should be a method there! >Did you change a migration after having run it (for example to add subject_id to the books table). Rails won''t notice if you do that. You either need to create a new migration when you want a changed like that or you need to migrate down and then up again. Fred --~--~---------~--~----~------------~-------~--~----~ 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@googlegroups.com For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
Hi, So you''re on here too huh? I think the problem is you''re trying to access the subject model from within the book model...so rails is not gonna understand what subject_id is and is therefore probably looking for a method by that name which doesn''t exist. I haven''t tried this out myself yet but I think this might help you: http://railscasts.com/episodes/73 On Jun 7, 5:33 am, nuky <inuk...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> Hello, > > I''m pretty new to Ruby on Rails (ROR) so I''m sorry if this is a silly > thing to ask. I have tried looking at several tutorials online but > most of them are for the earlier version of ROR and even the API is > not helping me too much! > > Basically I would like to create a drop down list in a form. I have > simplified my problem so that you''ll be able to understand it in a few > lines. > > A simple diagram is here:http://learningspirit.co.uk/class_diagram.png > > The migration and model files are here: > ## db/migrate/003_books.rb > class Books < ActiveRecord::Migration > def self.up > create_table :books do |t| > t.column :title, :string, :limit => 32, :null => false > t.column :price, :float > t.column :subject_id, :integer > t.column :description, :text > t.column :created_at, :timestamp > end > end > > def self.down > drop_table :books > end > end > > ## db/migrate/004_subjects.rb > class Subjects < ActiveRecord::Migration > def self.up > create_table :subjects do |t| > t.column :name, :string > end > > Subject.create :name => "Physics" > Subject.create :name => "Mathematics" > Subject.create :name => "Chemistry" > Subject.create :name => "Psychology" > Subject.create :name => "Geography" > end > > def self.down > drop_table :subjects > end > end > > ## app/model/book.rb > class Book < ActiveRecord::Base > belongs_to :subject > validates_presence_of :title > validates_numericality_of :price, :message=>"Error message" > end > > ## app/model/subject.rb > class Subject < ActiveRecord::Base > has_many :books > end > > The relevant book_controller.rb methods are: > def new > @book = Book.new > @subjects = Subject.find(:all) > end > > def create > @book = Book.new(params[:book]) > if @book.save > redirect_to :action => ''list'' > else > @subjects = Subject.find(:all) > render :action => ''new'' > end > end > > The problem I have is in the view for the form to create a new book > entry. The view (app/views/book/new.html.erb) is looking like this at > the moment: > > <h1>Add new book</h1> > <% form_for :book, @book, :url => { :action => "create" } do |f| %> > <p> > <label>Title</label>: > <%= text_field @book, :title %> > </p> > <p> > <label>Price</label>: > <%= text_field @book, :price %> > </p> > <p> > <label>Subject</label>: > <%= collection_select :book, :subject_id, @subjects, :id, :name %> > </p> > <p> > <label>Description</label>: > <%= text_area @book, :description %> > </p> > <p> > <%= f.submit "Create"%> > </p> > <% end %> > <%= link_to ''Back'', {:action => ''list''} %> > > My problem is that I cannot get the drop down list to work! I have > tried select (instead of collection_sort) but I am always getting > errors. At the moment I have the following error: > > undefined method `subject_id'' for #<Book id: nil, created_at: nil, > updated_at: nil> > > I don''t understand this at all because from the documentation, there > should be a method there! > > Please could some help me? What exactly are the arguments for the > collection_select method? What is wrong with my collection_select > call? > > Thank you very much and I hope this wasn''t too long winded! > Inuka.--~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
Thank you for the replies!
It turns out that there were many problems with my form. I fixed them
and it is pasted below in case it will be of some use to someone else
having problems with collection_sort!
% if flash[:notice] %>
<%= flash[:notice] %>
<% end %>
<h1>Add new book</h1>
<% form_for :book, @book, :url => { :action => "create" } do
|f| %>
<p>
Title:
<%= f.text_field :title %>
</p>
<p>
Price:
<%= f.text_field :price %>
</p>
<p>
Subject:
<%= f.collection_select :subject_id, @subjects, :id, :name %>
</p>
<p>
Description:
<%= f.text_area :description %>
</p>
<p>
<%= f.submit "Create"%>
</p>
<% end %>
<%= link_to ''Back'', {:action =>
''list''} %>
Thank you.
On Jun 7, 11:30 am, Housni
<housni.yak...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Hi,
> So you''re on here too huh?
>
> I think the problem is you''re trying to access the subject model
from
> within the book model...so rails is not gonna understand what
> subject_id is and is therefore probably looking for a method by that
> name which doesn''t exist.
>
> I haven''t tried this out myself yet but I think this might help
you:http://railscasts.com/episodes/73
>
> On Jun 7, 5:33 am, nuky
<inuk...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> > Hello,
>
> > I''m pretty new to Ruby on Rails (ROR) so I''m sorry
if this is a silly
> > thing to ask. I have tried looking at several tutorials online but
> > most of them are for the earlier version of ROR and even the API is
> > not helping me too much!
>
> > Basically I would like to create a drop down list in a form. I have
> > simplified my problem so that you''ll be able to understand it
in a few
> > lines.
>
> > A simple diagram is here:http://learningspirit.co.uk/class_diagram.png
>
> > The migration and model files are here:
> > ## db/migrate/003_books.rb
> > class Books < ActiveRecord::Migration
> > def self.up
> > create_table :books do |t|
> > t.column :title, :string, :limit => 32, :null
=> false
> > t.column :price, :float
> > t.column :subject_id, :integer
> > t.column :description, :text
> > t.column :created_at, :timestamp
> > end
> > end
>
> > def self.down
> > drop_table :books
> > end
> > end
>
> > ## db/migrate/004_subjects.rb
> > class Subjects < ActiveRecord::Migration
> > def self.up
> > create_table :subjects do |t|
> > t.column :name, :string
> > end
>
> > Subject.create :name => "Physics"
> > Subject.create :name => "Mathematics"
> > Subject.create :name => "Chemistry"
> > Subject.create :name => "Psychology"
> > Subject.create :name => "Geography"
> > end
>
> > def self.down
> > drop_table :subjects
> > end
> > end
>
> > ## app/model/book.rb
> > class Book < ActiveRecord::Base
> > belongs_to :subject
> > validates_presence_of :title
> > validates_numericality_of :price, :message=>"Error
message"
> > end
>
> > ## app/model/subject.rb
> > class Subject < ActiveRecord::Base
> > has_many :books
> > end
>
> > The relevant book_controller.rb methods are:
> > def new
> > @book = Book.new
> > @subjects = Subject.find(:all)
> > end
>
> > def create
> > @book = Book.new(params[:book])
> > if @book.save
> > redirect_to :action =>
''list''
> > else
> > @subjects = Subject.find(:all)
> > render :action => ''new''
> > end
> > end
>
> > The problem I have is in the view for the form to create a new book
> > entry. The view (app/views/book/new.html.erb) is looking like this at
> > the moment:
>
> > <h1>Add new book</h1>
> > <% form_for :book, @book, :url => { :action =>
"create" } do |f| %>
> > <p>
> > <label>Title</label>:
> > <%= text_field @book, :title %>
> > </p>
> > <p>
> > <label>Price</label>:
> > <%= text_field @book, :price %>
> > </p>
> > <p>
> > <label>Subject</label>:
> > <%=collection_select:book, :subject_id, @subjects, :id, :name %>
> > </p>
> > <p>
> > <label>Description</label>:
> > <%= text_area @book, :description %>
> > </p>
> > <p>
> > <%= f.submit "Create"%>
> > </p>
> > <% end %>
> > <%= link_to ''Back'', {:action =>
''list''} %>
>
> > My problem is that I cannot get the drop down list to work! I have
> > tried select (instead of collection_sort) but I am always getting
> > errors. At the moment I have the following error:
>
> > undefined method `subject_id'' for #<Book id: nil,
created_at: nil,
> > updated_at: nil>
>
> > I don''t understand this at all because from the
documentation, there
> > should be a method there!
>
> > Please could some help me? What exactly are the arguments for the
> >collection_selectmethod? What is wrong with mycollection_select
> > call?
>
> > Thank you very much and I hope this wasn''t too long winded!
> > Inuka.
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