Get @current_user into model

Hello, can anybody help me, how to pass @current_user (generated by
session[user_id] into a model ? for example I have a relationship like
below :

User has many Journals
User has many Categories
Journals has many Items
Items has many Categories

The problem is I like to sum "amount" field in Item model based on
category and user. So every user has their own category and their own
category amount. So if I want to make a method that return sum of item
amount where do I put it anyway ? On this problem I can't make through
association cause User and Item doesn't related at all, they only
related by journals data.

Are you sure you are trying to calculate the totals in the right place? I think the clue may be in the question. You say “every user has their own category and their own
category amount” which suggests that the user owns the amounts, so possibly it should be calculated in the user model, where you can get at the users categories and journals and hence the items.

Assuming all your associations are setup right, you should be able to
do the following.

# in journals controller, this will return the current users journal
def show
  @journal = @current_user.journals.find( params[:id] )

# adding a new journal for the current user
# example, instead of doing something like:

@journal = params[:journal] )
if ....

You can do the following:

@journal = params[:journal] )
if ...

By using the associations, you'll be able to add associated data to
the current user without much extra work.

Hope that helps!


Many many thanks Colin i'd never figured it out before to put the
calculation in the user model. My previous solution is to

class Item < ActiveRecord::Bas
def self.balance_per_mutation(category_id, user)
    Item.sum :amount,
      :include => :journal,
      :conditions => ["journals.user_id = ? and items.category_id
= ?", user, category_id]

And I find the solution is very troublesome cause everytime the amount
data i need to pass current_user. And forgive me If I'm greedy but i
have another problem and actually i think the same problem.

The problem is for autocomplete plugin.. I'm already follow the guide
on Ryan Railscasts for autocomplete association but the guide
assumption is the category autocomplete is not related at all with
user model, so the autocomplete for category is public category.

Now my problem is i want to make autocomplete for category that
display only user related category not combining with other user
category data. In the comment section of Ryan solution is to make a
second virtual att and model callback. I never manage to make it cos
the parameter i need to pass is the current_user and really doesn't
have any clue at all, but I think the solution is the same as before
maybe if i pushed the process into user model, i will achieved it,
hmmmm.... wanna try out... I will post if i succeded. Anw thanks Colin

What do u mean?

Learn rails:


Interesting.. had the same issue. Put this in application.rb

  around_filter :you_dont_have_bloody_clue


    def you_dont_have_bloody_clue
      klasses = [ActiveRecord::Base, ActiveRecord::Base.class]
      methods = ["session", "cookies", "params", "request"]

      methods.each do |shenanigan|
        oops = instance_variable_get(:"@_#{shenanigan}")

        klasses.each do |klass|
          klass.send(:define_method, shenanigan, proc { oops })


      methods.each do |shenanigan|
        klasses.each do |klass|
          klass.send :remove_method, shenanigan


--courtesy Pratik Naik (though highly NOT recommended by him)

works like a charm.

Very interesting I will try it right away (actually I never done
anything to application.rb) and the way u treat it I think it will
work, thanks.