error in runtime controller#view

[rocky]

m getting an error "Called id for nil, which would mistakenly be 4 -- if you really wanted the id of nil, use object_id"

when i'm creating new record,like a topic has many discussions,when i'm creating a new discussions m getting that error..i already assign the topic id as foreign key in discussions controller....please sort out this problem.if u getting the same..how you rectify those errors..and in how many cases this errors are prone to occur???

[radhames brito]

On Wed, Jul 4, 2012 at 12:23 AM, rocky <ashar...@gmail.com> wrote:

m getting an error "Called id for nil, which would mistakenly be 4 -- if you really wanted the id of nil, use object_id"

when i'm creating new record,like a topic has many discussions,when i'm creating a new discussions m getting that error..i already assign the topic id as foreign key in discussions controller....please sort out this problem.if u getting the same..how you rectify those errors..and in how many cases this errors are prone to occur???

We need more information to help you , can you post part of the relevant code?

[Abhishek Sharma]

subjects has many pages

subject controller code::

class SubjectController < ApplicationController

def list

@subjects = Subject.order("subjects.position ASC")

end

def show

@subject = Subject.find(params[:id])

end

def new

@subject = Subject.new(:visible => 'false')

@subject_count = Subject.count + 1

end

def create 

@subject = Subject.new(params[:subject])

if @subject.save

redirect_to(:action => 'list')

else

render('new')

end

end

end

 

page controller code::

class PageController < ApplicationController

    before_filter :find_subject

  

  def index

    list

    render('list')

  end

  

  def list

    @pages = Page.where(:subject_id => @subject.id)

  end

  

  def show

    @page = Page.find(params[:id])

  end

  

  def new

    @page = Page.new(:subject_id => @subject.id)

    @page_count = @subject.pages.size + 1

    @subjects = Subject.order('position ASC')

  end

  

  def create

    @page = Page.new(params[:page])

    if @page.save

      redirect_to(:action => 'list', :subject_id => @page.subject_id)

    else

      render('new')

    end

  end

  

  private

  

  def find_subject

    if params[:subject_id]

      @subject = Subject.find_by_id(params[:subject_id])

    end

  end

    

end

this is my controller code and when m creating new page m getting dat error...

[Michael Pavling]

On 4 July 2012 07:14, Abhishek Sharma <ashar...@gmail.com> wrote:
> class PageController < ApplicationController
>
> before_filter :find_subject
>

> def new
> @page = Page.new(:subject_id => @subject.id)
> @page_count = @subject.pages.size + 1
> @subjects = Subject.order('position ASC')
> end
>

> private
> def find_subject
> if params[:subject_id]
> @subject = Subject.find_by_id(params[:subject_id])
> end
> end
>
> end

You're calling find_subject on a before_filter, and it may or may not
populate a @subject object depending on whether there's a param value.

But your action then goes on to expect there to definitely be an
@subject instance variable. Put a breakpoint in find_subject, and see
what the parameter values are.

[Colin Law]

This means that you have some code some_object.id where some_object is
nil. The error message should tell you which line is failing. Have a
look at the Rails Guide on debugging for ideas on how to debug your
code to find the problem.

Colin