Hello,
i have two models :
class Container < ActiveRecord::Base
has_many :bottles
end
class Bottle < ActiveRecord::Base
belongs_to :container
def self.find_all_from_container(container)
container.bottles.find(:all)
end
end
i was asking myself if there was a better way to write the function
find_all_from_container : i can call it from an instance of Container
but how to pass the container instance directly (ie without giving
the argument). To replace this :
@container = Container.find(id)
@bottles = Bottle.find_all_from_container(@container)
by something like this :
@container . Container.find(id)
@bottles = @container.bottles.find_all_from_container
Hi,
2007/8/2, Fabien J. [email protected]:
end
…
To replace this :
@container = Container.find(id)
@bottles = Bottle.find_all_from_container(@container)
by something like this :
@container . Container.find(id)
@bottles = @container.bottles.find_all_from_container
has_many gives you what you want for free.
@container.bottles
results in all bottles in the container. No need to call find.
Lutz
On Aug 2, 2007, at 12:02 PM, Lutz H. wrote:
by something like this :
@container . Container.find(id)
@bottles = @container.bottles.find_all_from_container
has_many gives you what you want for free.
@container.bottles
results in all bottles in the container. No need to call find.
I should have add more code in find_all_from_container function. The
idea is not to get every entries but to scope entries and perform
some actions on them, like :
def self.fill_empty(container)
bottles = container.bottles.find(:all, :conditions => {:is_empty
=> true})
bottles.each {|bottle| bottle.fill}
end
On Aug 2, 2007, at 12:13 PM, Lutz H. wrote:
=> true})
bottles.each {|bottle| bottle.fill}
end
You can do this by using select:
container.bottles.select { |bottle| bottle.is_empty }
The block given to select must return true for every object to be
included in the resulting list.
Thanks for this help, but i just want to get the container instance
in class function to perform various things, regardless of any code
in it.
Hi,
2007/8/2, Fabien J. [email protected]:
I should have add more code in find_all_from_container function. The
idea is not to get every entries but to scope entries and perform
some actions on them, like :
def self.fill_empty(container)
bottles = container.bottles.find(:all, :conditions => {:is_empty
=> true})
bottles.each {|bottle| bottle.fill}
end
You can do this by using select:
container.bottles.select { |bottle| bottle.is_empty }
The block given to select must return true for every object to be
included in the resulting list.
Lutz
On Aug 2, 2007, at 12:22 PM, Pratik wrote:
It really helps if you can ask your question with exact code you’re
using.
actually, there is no code about this, i just want to know if it is
possible to get the instance without explicitly giving it in the call.
This is more by curiosity rather than a strict code question.
It really helps if you can ask your question with exact code you’re
using.
On 8/2/07, Fabien J. [email protected] wrote:
@container = Container.find(id)
end
–
Cheers!
Hi –
On Thu, 2 Aug 2007, Fabien J. wrote:
This is more by curiosity rather than a strict code question.
The thing is, the instance is the class object when you call a class
method:
class C
end
def C.greet
puts “Hi from #{self}”
end
C.greet # Hi from C
There’s no instance of C involved; you’re sending the message directly
to C. A class is (by design) an entirely different object from its
instances (except for constants, which an instance method can refer
to from “below”, and except for class variables, which are weird and
quasi-global).
It’s possible to engineer things so that a class method can have
access of a sort to an instance via a block. Here’s an example (and
if you look at the source code for AR associations, which let you do
things like this, you’ll see some much more highly-evolved examples):
class A
def self.c_method(&block)
include Module.new { define_method(“m”, &block) }
end
end
class B < A
c_method { puts “Hi; I’m #{self}.” }
end
B.new.m # Hi; I’m #<B:0x1ea08c>.
It’s not exactly what you want, but it might give you some ideas.
David
–