I am having trouble with this bit of code
if request.get?
session[:user_id] = nil
@user = User.new
logger.error("get:#{@user.object_id}")
else
logger.error("post:#{@user.object_id}")
logged_in_user = @user.try_to_login
if logged_in_user
session[:user] = logged_in_user.id
redirect_to(:action => "index")
else
flash[:notice] = "Invalid user/password combo"
end
For some reason, when posting back the object_id of the @user variable
is 4 but when the get? is executed, the object_id is 28208630.
The error message is
NoMethodError (You have a nil object when you didn''t expect it!
The error occured while evaluating nil.try_to_login):
This happens if i enter a user name and password or leave them both
blank, and yes there is a method called try_to_login. Im trying to learn
rails and the code is exactly as is written in the book. Could something
have changed in rails since the book was published?
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Cayce Balara
2006-Nov-06 03:47 UTC
Re: Instance variable not holding between get? and post
Hey Flipper - Which book? When you get to the line: logged_in_user = @user.try_to_login on the postback, you have not yet defined @user, thus the "nil.try_to_login" error. Somewhere before that line you need to create the @user instance variable as a new user object, probably by passing in the parameters from the form, something like: @user = User.new(params[:user]) Or even better, you don''t really need the @user object at that point, so you could just do something like this: logged_in_user = User.new(params[:user]).try_to_login Check the code in your book again - they''ve got to be creating the @user somewhere in the code before you get to that line. It doesn''t just come back in fully-formed from the login view form without you doing anything in the controller to create it. c. Flippper wrote:> I am having trouble with this bit of code > > if request.get? > session[:user_id] = nil > @user = User.new > > logger.error("get:#{@user.object_id}") > else > logger.error("post:#{@user.object_id}") > > logged_in_user = @user.try_to_login > > if logged_in_user > session[:user] = logged_in_user.id > redirect_to(:action => "index") > else > flash[:notice] = "Invalid user/password combo" > end > > For some reason, when posting back the object_id of the @user variable > is 4 but when the get? is executed, the object_id is 28208630. > > The error message is > > NoMethodError (You have a nil object when you didn''t expect it! > The error occured while evaluating nil.try_to_login): > > > This happens if i enter a user name and password or leave them both > blank, and yes there is a method called try_to_login. Im trying to learn > rails and the code is exactly as is written in the book. Could something > have changed in rails since the book was published?-- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
Cayce Balara wrote:> Hey Flipper - > > Which book? > > When you get to the line: > > logged_in_user = @user.try_to_login > > on the postback, you have not yet defined @user, thus the > "nil.try_to_login" error. Somewhere before that line you need to create > the @user instance variable as a new user object, probably by passing in > the parameters from the form, something like: > > @user = User.new(params[:user]) > > Or even better, you don''t really need the @user object at that point, so > you could just do something like this: > > logged_in_user = User.new(params[:user]).try_to_login > > Check the code in your book again - they''ve got to be creating the @user > somewhere in the code before you get to that line. It doesn''t just come > back in fully-formed from the login view form without you doing anything > in the controller to create it. > > c.Thanks very much for that, it worked. Although I dont understand why it needs to be reassigned. Why would I @user = User.new in the get? and then recreate the User object again at post? The book mentioned that form data will be stored in the @user object so woulden''t recreating it lose the information? -- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
CatLady [] wrote:> > Thanks very much for that, it worked. > > Although I dont understand why it needs to be reassigned. > > Why would I @user = User.new in the get? and then recreate the User > object again at post? > > The book mentioned that form data will be stored in the @user object so > woulden''t recreating it lose the information?I believe what you want is: @user = User.new(params[:user]) This creates a new user object, but from the parameters passd in from the form that just submitted it. The form doesn;t store the object itself, just its attributes. And instance variables in controllers are only alive for the length of a single request. Once a second request comes in a new instane of the controller is created so all instance variables are lost. -- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
Cayce Balara
2006-Nov-06 13:46 UTC
Re: Instance variable not holding between get? and post
Because HTTP is a ''stateless'' protocol. Between hitting the page for the first time when rails does @user = User.new and the user submitting the form with data, the server (and rails) completely ''forgets'' what''s going on. Each request, whether it is the first hit on the page (the GET) or the submission of data (the POST), is a separate and distinct request to the server. The server does not maintain any state data in between - from its perspective, that @user variable is destroyed once the request completes. When the form is submitted, the data you filled in are part of the POST header in the request. Rails picks this data out and populates the params[] hash with it, giving you easy access to the data, but rails really has no idea what kind of data that is or what you want to do with it - that''s up to you. In this case, you have need of an object of a particular class, so you create it. In other cases, maybe you just need a particular piece of submitted data, so you''d access it in params[]. c.> > Thanks very much for that, it worked. > > Although I dont understand why it needs to be reassigned. > > Why would I @user = User.new in the get? and then recreate the User > object again at post? > > The book mentioned that form data will be stored in the @user object so > woulden''t recreating it lose the information?-- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---