I am trying to store status information, but whenever I tried to call
the methods inside the session object, it would complain about this:
NoMethodError in TestController#getstatus
You have a nil object when you didn''t expect it!
You might have expected an instance of Array.
The error occured while evaluating nil.include?
Here''s the code I use:
class TestController < ApplicationController
def index
end
def getlog
session[:s1] ||= Status.new
render :text => session[:s1].gettext
end
end
class Status < ActiveRecord::Base
@@ccount = 0
def self.gettext
@@ccount += 1
end
end
--
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Wai Tsang wrote:> I am trying to store status information, but whenever I tried to call > the methods inside the session object, it would complain about this: > > NoMethodError in TestController#getstatusYour session store in files like tmp/sessions/ruby_sess.ff73c12d9549c9de . Open one as text and read it. It shows "serialized" objects, meaning object that are converted into strings for cold storage. Ruby objects are supposed to live in memory; think of them as 2D entities. Strings can only contain 1D entities. Some objects can''t handle the flattening process; it squeezes the life out of them. By and large, don''t use the session object unless you must. And between two events (two controller actions, for example), never assume that the Ruby process running Rails is the same instance. The session hash cannot store a reference to an object in memory (like a real Hash would), it can only store a serialized copy of the object. All communication between two events should be as thin and simple as possible. Store your object in a Model with an id, and pass this id between events somehow. I prefer to pass it as hidden fields in the View, but you can go ahead and use the session hash for that. -- Phlip http://www.greencheese.us/ZeekLand <-- NOT a blog!!! --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
Phlip wrote:> Wai Tsang wrote: > >> I am trying to store status information, but whenever I tried to call >> the methods inside the session object, it would complain about this: >> >> NoMethodError in TestController#getstatus > > Your session store in files like tmp/sessions/ruby_sess.ff73c12d9549c9de > . > > Open one as text and read it. It shows "serialized" objects, meaning > object > that are converted into strings for cold storage. > > Ruby objects are supposed to live in memory; think of them as 2D > entities. > Strings can only contain 1D entities. Some objects can''t handle the > flattening process; it squeezes the life out of them. > > By and large, don''t use the session object unless you must. And between > two > events (two controller actions, for example), never assume that the Ruby > process running Rails is the same instance. The session hash cannot > store a > reference to an object in memory (like a real Hash would), it can only > store > a serialized copy of the object. > > All communication between two events should be as thin and simple as > possible. Store your object in a Model with an id, and pass this id > between > events somehow. I prefer to pass it as hidden fields in the View, but > you > can go ahead and use the session hash for that. > > -- > Phlip > http://www.greencheese.us/ZeekLand <-- NOT a blog!!!Thanks for the quick reply. I tried storing the information in the model, but the information in the model cannot be retained. For example, if I stored an global class variable @@ccount in Status, and Status.gettext would increase the @ccount, when I output the value of gettext in Status, it is always 1. It seems like the model is created from scratch everytime the controller tried to call the methods inside. -- 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 -~----------~----~----~----~------~----~------~--~---
i think you should use the global var,start with "$" the class-var is not persisstence between user-actions. On 2月4日, 下午11时56分, Wai Tsang <rails-mailing-l...@andreas-s.net> wrote:> Phlip wrote: > > Wai Tsang wrote: > > >> I am trying to store status information, but whenever I tried to call > >> the methods inside the session object, it would complain about this: > > >> NoMethodError in TestController#getstatus > > > Your session store in files like tmp/sessions/ruby_sess.ff73c12d9549c9de > > . > > > Open one as text and read it. It shows "serialized" objects, meaning > > object > > that are converted into strings for cold storage. > > > Ruby objects are supposed to live in memory; think of them as 2D > > entities. > > Strings can only contain 1D entities. Some objects can''t handle the > > flattening process; it squeezes the life out of them. > > > By and large, don''t use the session object unless you must. And between > > two > > events (two controller actions, for example), never assume that the Ruby > > process running Rails is the same instance. The session hash cannot > > store a > > reference to an object in memory (like a real Hash would), it can only > > store > > a serialized copy of the object. > > > All communication between two events should be as thin and simple as > > possible. Store your object in a Model with an id, and pass this id > > between > > events somehow. I prefer to pass it as hidden fields in the View, but > > you > > can go ahead and use the session hash for that. > > > -- > > Phlip > > http://www.greencheese.us/ZeekLand<-- NOT a blog!!! > > Thanks for the quick reply. I tried storing the information in the > model, but the information in the model cannot be retained. For > example, if I stored an global class variable @@ccount in Status, and > Status.gettext would increase the @ccount, when I output the value of > gettext in Status, it is always 1. It seems like the model is created > from scratch everytime the controller tried to call the methods inside. > > -- > Posted viahttp://www.ruby-forum.com/.- 隐藏被引用文字 - > > - 显示引用的文字 ---~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
Vicent.Z wrote:> i think you should use the global var,start with "$" > the class-var is not persisstence between user-actions.Never do that, because (among many other reasons) you should never assume that the Ruby instance that serves one Action is the same as serves the next one. Your server could reboot, for example, between each time the user looks at a View. Wai Tsang wrote:> Thanks for the quick reply. I tried storing the information in the > model, but the information in the model cannot be retained. For > example, if I stored an global class variable @@ccount in Status, and > Status.gettext would increase the @ccount, when I output the value of > gettext in Status, it is always 1. It seems like the model is created > from scratch everytime the controller tried to call the methods inside.What is ccount? The first step here is to give it a complete, self-documenting name. Programs are hard enough to read without abusing private acronyms. Do you really need a variable to count something, for the lifespan of the Rails website, such that each user sees a new value in it? If so, I would store it in a YAML file, and open it at a path like RAILS_ROOT + ''/lib/my.yaml''. Then YAML::load it when you need it and YAML::dump it when it changes. If you don''t want to do that, note the only members of a Model that store in a database are the attribute ones - not any extra variable you make, and certainly not the class-instance @@ variables. Make another Model and put only one record in it, with ccount in that (with a better name). Then find(:first) this Model instance when you need the record, and save it when it changes. -- Phlip http://www.greencheese.us/ZeekLand <-- NOT a blog!!! --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
Phlip wrote:> Do you really need a variable to count something, for the lifespan of > the > Rails website, such that each user sees a new value in it? If so, I > would > store it in a YAML file, and open it at a path like RAILS_ROOT + > ''/lib/my.yaml''. Then YAML::load it when you need it and YAML::dump it > when > it changes. > > If you don''t want to do that, note the only members of a Model that > store in > a database are the attribute ones - not any extra variable you make, and > certainly not the class-instance @@ variables. > > Make another Model and put only one record in it, with ccount in that > (with > a better name). Then find(:first) this Model instance when you need the > record, and save it when it changes. > > -- > Phlip > http://www.greencheese.us/ZeekLand <-- NOT a blog!!!It is just a sample code, but yeah, I would need to store some information about the session, such as whether an action has been completed and how many times it has been ran. I will look into YAML, thanks a lot. -- 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 -~----------~----~----~----~------~----~------~--~---