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Michael Henry

2006-Dec-20 22:37 UTC

belongs_to behaviour and missing method updated?

Hi,

I''ve got a really simple model and controller which are producing an
error. The model is one line:

    class NaturalPerson < ActiveRecord::Base
      belongs_to :nationality, {:class_name => "Country"}
    end

and the controller, specifically the create action, is equally simple:

    class NaturalPeopleController < ApplicationController
      def create
        person = NaturalPerson.new(params[:natural_person])

        if person.save
          flash[:notice] = "Person was successfully created"
          redirect_to :action => "list"
        else
          render_scaffold(''new'')
        end
      end
    end

If I run the code like this I get this error:

    ActiveRecord::AssociationTypeMismatch in Natural
peopleController#create
    Country expected, got String

I have given ActiveRecord enough information to know it should
instantiate a Country and assign to "nationality", no?

OK, so I need to do it myself in a constructor for the NaturalPerson
model:

  def initialize(params)
    @postal_address = params[:postal_address]
    @fax_number = params[:fax_number]
    @name = params[:name]
    @phone_number = params[:phone_number]
    @dob = Date.civil(params["dob(1i)"].to_i,
params["dob(2i)"].to_i,
         params["dob(3i)"].to_i)
    @visa =params[:visa]
    @mobile_number = params[:mobile_number]
    @email_address = params[:email_address]
    @nationality = Country.find(params[:nationality].to_i)
  end

Now I get this error:

    NoMethodError in Natural peopleController#create
    undefined method `updated?'' for #<Country:0x412cb0a0
      @attributes={"name"=>"TONGA",
"id"=>"220"}>

A search of the web and usenet suggests that the "definitive" reason
for
this error is described in this post:

http://lists.rubyonrails.org/pipermail/rails/2006-March/026246.html

    "my problem was caused by a badly chosen name of a variable
     in the validates method of my interface model. Originally
     I called it @device, after renaming it the error was gone."

Unfortuately the post doesn''t say what it was about the variable name
what was bad. This thread provides another useful tidbit of information:

http://groups.google.com/group/rubyonrails-talk/browse_thread/thread/28afcde31492865f/11bbc512dd6215bf?lnk=st&q=undefined+method+%60updated%3F%27&rnum=1#11bbc512dd6215bf

    "Looking back at the reason, it would never get into the block
     that I mentioned in my original post if the :belongs_to object
     is null and if i have a different variable name, that would be
     the case and the association is only saved due to the link
     from the Doctor''s side."

OK. In my case the belongs_to object *is* nil because it hasn''t been
assigned a value yet.

The name of my foreign key was originally "nationality" but, without
really knowing what was causing the problem, I thought there might be
some conflict with the instance variable so I changed the field to
"country_id". Hence this code in the model:

    belongs_to :nationality, {:class_name => "Country"}

which implies a foreign key of "country_id".

So I''m at a point where I don''t think the previous examples of
this
error apply to me. If anyone has any suggestions I would be extremely
grateful!

Regards,

    Michael

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Agnieszka Figiel

2006-Dec-21 10:56 UTC

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Re: belongs_to behaviour and missing method updated?

Michael Henry wrote:> Hi,
> 
> I''ve got a really simple model and controller which are producing
an
> error. The model is one line:
Hello,

it would be helpful to know what params[:natural_person] looks like to 
analyze the first of the errors you described (one without overriding 
the constructor)

--
Agnieszka Figiel

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Michael Henry

2006-Dec-22 01:04 UTC

head link

Re: belongs_to behaviour and missing method updated?

Agnieszka Figiel wrote:> Michael Henry wrote:
>> Hi,
>> 
>> I''ve got a really simple model and controller which are
producing an
>> error. The model is one line:
> 
> Hello,
> 
> it would be helpful to know what params[:natural_person] looks like to 
> analyze the first of the errors you described (one without overriding 
> the constructor)
Sure, here it is with some formatting to make it more readable:

Parameters: {
    "natural_person"=> {
        "postal_address"=>"",
        "fax_number"=>"",
        "name"=>"Maikolo",
        "phone_number"=>"",
        "dob(1i)"=>"2006",
        "visa"=>"",
        "dob(2i)"=>"12",
        "dob(3i)"=>"14",
        "mobile_number"=>"",
        "email_address"=>"",
        "nationality"=>"220"
    },
    "commit"=>"Create"
}

The view that produced the drop-down for "Nationality" looks like
this:

<p>
  <label
for="natural_person_nationality">Nationality</label>
  <br />
  <select id="natural_person_nationality" 
name="natural_person[nationality]" />
    <%= options_from_collection_for_select(@countries, :id, :name, 
@selected) %>
  </select>
</p>

...where @countries and @selected are defined in the controller as:

    @countries = Country.find(:all)
    @selected = Country.find_by_name("TONGA").id

@selected has the value of 220 (I didn''t change the country before 
submitting the form).

Regards,

    Michael




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Michael Henry

2006-Dec-22 04:13 UTC

head link

Re: belongs_to behaviour and missing method updated?

I''ve found a workaround as outlined below.
> I''ve got a really simple model and controller which are producing
an
> error. The model is one line:
> 
>     class NaturalPerson < ActiveRecord::Base
>       belongs_to :nationality, {:class_name => "Country"}
>     end
I''ve made no changes to the model. The constructor I included in my 
initial post has been discarded.
> and the controller, specifically the create action, is equally simple:
> 
>     class NaturalPeopleController < ApplicationController
>       def create
>         person = NaturalPerson.new(params[:natural_person])
> 
>         if person.save
>           flash[:notice] = "Person was successfully created"
>           redirect_to :action => "list"
>         else
>           render_scaffold(''new'')
>         end
>       end
>     end
I''ve inserted this line of code before I instantiate the NaturalPerson:

    params[:natural_person][:nationality] = 
Country.find(params[:country].to_i)

Note that I''m referring to a new form element: "country". I
have changed
the view so that this is the name of the country drop-down.

I don''t suppose anybody''s reading this but it gives me a sense
of
closure to put my workaround on the list :)

Michael



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Adam Rails

2006-Dec-22 20:01 UTC

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Re: belongs_to behaviour and missing method updated?

Just thinking out loud here..

What about if you changed the parameter to nationality_id instead of
nationality.  That way, when the constructor is creating the object calls
the method nationality_id= which is expecting a integer instead of the the
method its currently calling nationality= which is created from the
belongs_to declaration.

In either case, your workaround does the trick but this might be a little
more efficient.

Adam

On 12/21/06, Michael Henry
<rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:>
>
> I''ve found a workaround as outlined below.
>
> > I''ve got a really simple model and controller which are
producing an
> > error. The model is one line:
> >
> >     class NaturalPerson < ActiveRecord::Base
> >       belongs_to :nationality, {:class_name => "Country"}
> >     end
>
> I''ve made no changes to the model. The constructor I included in
my
> initial post has been discarded.
>
> > and the controller, specifically the create action, is equally simple:
> >
> >     class NaturalPeopleController < ApplicationController
> >       def create
> >         person = NaturalPerson.new(params[:natural_person])
> >
> >         if person.save
> >           flash[:notice] = "Person was successfully created"
> >           redirect_to :action => "list"
> >         else
> >           render_scaffold(''new'')
> >         end
> >       end
> >     end
>
> I''ve inserted this line of code before I instantiate the
NaturalPerson:
>
>     params[:natural_person][:nationality] >
Country.find(params[:country].to_i)
>
> Note that I''m referring to a new form element:
"country". I have changed
> the view so that this is the name of the country drop-down.
>
> I don''t suppose anybody''s reading this but it gives me a
sense of
> closure to put my workaround on the list :)
>
> Michael
>
>
>
> --
> Posted via http://www.ruby-forum.com/.
>
> >
>
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Michael Henry

2006-Dec-24 01:02 UTC

head link

Re: belongs_to behaviour and missing method updated?

Adam Rails wrote:> What about if you changed the parameter to nationality_id instead of
> nationality.
Do you mean the association? It originally referred to a foreign key 
which was also called "nationality" but I changed the foreign key to 
"country_id" so that: a) it conforms to the ActiveRecord convention,
and
b) removes any possibility of conflict between the association and field 
names. Unfortunately this change didn''t affect the error.
>  That way, when the constructor is creating the object calls
> the method nationality_id= which is expecting a integer instead of the 
> the
> method its currently calling nationality= which is created from the
> belongs_to declaration.
The belongs_to invocation *should* cause the same code to be run 
regardless of the name of the association. I''m happy to be corrected on
that point. Also, I think the "_id" naming convention only applies to 
the database and as such should be kept in the persistence layer and not 
make its way to the middle tier of my application.
> In either case, your workaround does the trick but this might be a 
> little more efficient.
I''m in the early stages of developing this application so I''m
not that
bothered by efficiency yet. My main problem with the workaround is that 
the Country.find() method will have to be invoked every time I want to 
create a NaturalPerson. ie, it violates the DRY principle.

Michael



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Adam Rails

2006-Dec-29 11:03 UTC

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Re: belongs_to behaviour and missing method updated?

I was referring to the parameter passed in from the view...

so then your html would look like this:

<select id="natural_person_nationality_id"
name="natural_person[nationality_id]" />
   <%= options_from_collection_for_select(@countries, :id, :name,
@selected) %>

I believe that should work and not require querying the Nationality
database.

Adam


On 12/23/06, Michael Henry
<rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:>
>
> Adam Rails wrote:
> > What about if you changed the parameter to nationality_id instead of
> > nationality.
>
> Do you mean the association? It originally referred to a foreign key
> which was also called "nationality" but I changed the foreign key
to
> "country_id" so that: a) it conforms to the ActiveRecord
convention, and
> b) removes any possibility of conflict between the association and field
> names. Unfortunately this change didn''t affect the error.
>
> >  That way, when the constructor is creating the object calls
> > the method nationality_id= which is expecting a integer instead of the
> > the
> > method its currently calling nationality= which is created from the
> > belongs_to declaration.
>
> The belongs_to invocation *should* cause the same code to be run
> regardless of the name of the association. I''m happy to be
corrected on
> that point. Also, I think the "_id" naming convention only
applies to
> the database and as such should be kept in the persistence layer and not
> make its way to the middle tier of my application.
>
> > In either case, your workaround does the trick but this might be a
> > little more efficient.
>
> I''m in the early stages of developing this application so
I''m not that
> bothered by efficiency yet. My main problem with the workaround is that
> the Country.find() method will have to be invoked every time I want to
> create a NaturalPerson. ie, it violates the DRY principle.
>
> Michael
>
>
>
> --
> Posted via http://www.ruby-forum.com/.
>
> >
>
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Rails - Dec 2006 - belongs_to behaviour and missing method updated?

belongs_to behaviour and missing method updated?

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Re: belongs_to behaviour and missing method updated?

Re: belongs_to behaviour and missing method updated?