How to solve can not redirect to nil error?

rubyonrails-talk
1

I am using Ruby 1.9.3 and Rails 3.2.16. I follow "Agile web development with rails" book.

I am trying to make **Expense Management** application.

I am providing Heroku links as follow: " https://expense-management-app.herokuapp.com/manageexpense "

In above link, When I click on "Add to count" button then I can able to redirect to

"https://expense-management-app.herokuapp.com/expensescounters/6"

this link. It is working.

Now i create association between user and expensescounter to see the expenses for authorize user.

After creating association, when I click on "Add to count" button, I got error

like:

ActionController::ActionControllerError (Cannot redirect to nil!):

app/controllers/line_items_controller.rb:54:in `block (2 levels) in create'

app/controllers/line_items_controller.rb:51:in `create'

Code of line_items_controller.rb :

def create @expensescounter = current_expensescounter quantity = Quantity.find(params[:quantity_id]) @line_item = @expensescounter.add_quantity(quantity.id) @line_item.quantity = quantity

respond_to do |format| #line no. : 51   if @line_item.save    format.html { redirect_to @line_item.expensescounter } #line no. : 54 . . . . . end

How can I solve this problem?

Any help would be appreciated.

2

Can you create a gist with the code to repsoduce the error or post the full error stack trace, please ?

3

By doing some debugging. The error indicates that @lineitem.expensescounter is nil (the clue is that it says cannot redirect to nil) so you must find why this is the case. Look in your code to see where you set that up and work out why it is nil. A simple way of debugging to to insert lines like logger.info( some_expression ) which will insert text into development.log (and in the server window). You can use that to look at values and work out what is going wrong.

Colin

4

Can you create a gist with the code to repsoduce the error or post the full error stack trace, please ?

I am providing full error trace in following link:

5

You’re going to need to figure out why @line_item.expensescounter is nil. Post the code here if you need help finding the problem.

–Matt Jones

6

Matt Jones wrote in post #1155588:

You're going to need to figure out why @line_item.expensescounter is nil. Post the code here if you need help finding the problem.

Code of application_controller.rb:

class ApplicationController < ActionController::Base    protect_from_forgery    include SessionsHelper

   private      def current_expensescounter         Expensescounter.find(session[:expensescounter_id])       logger.info "expensescounter_id is #{(session[:expensescounter_id])}"         rescue ActiveRecord::RecordNotFound         expensescounter = Expensescounter.create         session[:expensescounter_id] = expensescounter.id         expensescouter      end end

Any help would be appreciated.

7

Matt Jones wrote in post #1155588:

You're going to need to figure out why @line_item.expensescounter is nil. Post the code here if you need help finding the problem.

Code of application_controller.rb:

class ApplicationController < ActionController::Base    protect_from_forgery    include SessionsHelper

   private      def current_expensescounter         Expensescounter.find(session[:expensescounter_id])       logger.info "expensescounter_id is #{(session[:expensescounter_id])}"

With the logger.info line here you have changed what this function returns, as now it will return the result from logger.info, not from the find. Move that line above the find call, then put another logger call in the rescue.

        rescue ActiveRecord::RecordNotFound         expensescounter = Expensescounter.create         session[:expensescounter_id] = expensescounter.id         expensescouter

That should be expensescounter not expensescouter, but that would give a different error if it ran so I presume that line of code has never been executed.

     end end

Any help would be appreciated.

I am assuming that neither of the problems I have noted above is causing the actual problem (as I assume you put the logger call in to try and diagnose it.

We went all round this last time you tried to ask this question a little time ago. You must show us the code where you set @line_item.expensescounter. The above code does not do that, it is just a private method of the controller that returns an Expensescounter object. If you do not understand what I am asking then please say so.

Colin

8

Colin Law wrote in post #1155814:

9

You have a variable called @line_item and are trying to reference the member @line_item.expensescounter. I assume that @line_item is an object of class LineItem. Is that correct?

Assuming the above is correct then what is LineItem.expensescounter? Is it an association, so in the lineitem class you have lineitem belongs_to Expensescounter or has_one Expensescounter? If so then at some point you should have made an expensescounter and assigned it to a lineitem object and saved them both in the database. Your error suggests that the lineitem object in @line_item does not have an associated expensescounter. So the code you need to show is how you create the expensescounter and then give it to the lineitem. All you have showed so far is a public method (current_expensescounter) which finds or creates one, but there is nothing to say that it belongs to the particular lineitem referenced by @lineitem.

Colin

10

Colin Law wrote in post #1155829:

You have a variable called @line_item and are trying to reference the member @line_item.expensescounter. I assume that @line_item is an object of class LineItem. Is that correct?

Yes, it is correct.

Assuming the above is correct then what is LineItem.expensescounter? Is it an association, so in the lineitem class you have lineitem belongs_to Expensescounter or has_one Expensescounter? If so then at some point you should have made an expensescounter and assigned it to a lineitem object and saved them both in the database. Your error suggests that the lineitem object in @line_item does not have an associated expensescounter. So the code you need to show is how you create the expensescounter and then give it to the lineitem. All you have showed so far is a public method (current_expensescounter) which finds or creates one, but there is nothing to say that it belongs to the particular lineitem referenced by @lineitem.

I have created relationship between line items, expensescounter and quantity.

It is an association between lineitem and expensescounter. I am providing code of model:

Code of cart.rb:

class Expensescounter < ActiveRecord::Base   attr_accessible :user_id

  has_many :line_items, dependent: :destroy   belongs_to :user

  validates :user_id, presence: true   default_scope order: 'expensescounters.created_at DESC' . . . end

code of line_item.rb:

class LineItem < ActiveRecord::Base    attr_accessible :quantity_id, :expensescounter_id

  belongs_to :quantity   belongs_to :expensescounter . . . end

code of quantity.rb:

class Quantity < ActiveRecord::Base . .   has_many :line_items

  before_destroy :ensure_not_referenced_by_any_line_item . . . end

11

Colin Law wrote in post #1155829:

Assuming the above is correct then what is LineItem.expensescounter? Is it an association, so in the lineitem class you have lineitem belongs_to Expensescounter or has_one Expensescounter? If so then at some point you should have made an expensescounter and assigned it to a lineitem object and saved them both in the database. Your error suggests that the lineitem object in @line_item does not have an associated expensescounter. So the code you need to show is how you create the expensescounter and then give it to the lineitem. All you have showed so far is a public method (current_expensescounter) which finds or creates one, but there is nothing to say that it belongs to the particular lineitem referenced by @lineitem.

In your last message, you given clue to solve this error.

Your error suggests that the lineitem object in @line_item does not have > an

associated expensescounter

This is main clue which help me to solve this error. By trying to solve this error i learn many things.

Thank you very much to you for helping me and you spent valuable time.

I solved this error because of you.

Again Thank you very much.

Warm regards.

12

Glad to of help.

Colin