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jeremy.bise-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

2007-Jul-14 18:15 UTC

Rails Noob, Math or Array Issue?

Let''s say that below is the math for figuring out a unit in a popular
diet program:

    @fiber = Array.new(@food.fiber, 4)
    @points = (@food.calories / 50) + (@food.fat / 12) - (@fiber.min /
5)

And that for personal use, I''m creating a system to keep track of
these units on a daily basis and I''m simply rendering @points in the
following manner in my view:

   <p><b>Points:</b> <%= @points %></p>

But when @points equals 0, I get the nasty message:

 NoMethodError in FoodsController#show

You have a nil object when you didn''t expect it!
The error occurred while evaluating nil./

What would one do to make it OK to have a 0 instead of causing it to
evaluate nil?


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jeremy.bise-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

2007-Jul-14 18:18 UTC

head link

Re: Rails Noob, Math or Array Issue?

I goofed up...when the minimum of @fiber = 0, I get the nasty
message...not when @points = 0.  I apologize.

On Jul 14, 2:15 pm,
"jeremy.b...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org"
<jeremy.b...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Let''s say that below is the math for figuring out a unit in a
popular
> diet program:
>
>     @fiber = Array.new(@food.fiber, 4)
>     @points = (@food.calories / 50) + (@food.fat / 12) - (@fiber.min /
> 5)
>
> And that for personal use, I''m creating a system to keep track of
> these units on a daily basis and I''m simply rendering @points in
the
> following manner in my view:
>
>    <p><b>Points:</b> <%= @points %></p>
>
> But when @points equals 0, I get the nasty message:
>
>  NoMethodError in FoodsController#show
>
> You have a nil object when you didn''t expect it!
> The error occurred while evaluating nil./
>
> What would one do to make it OK to have a 0 instead of causing it to
> evaluate nil?

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jeremy.bise-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

2007-Jul-14 19:16 UTC

head link

Re: Rails Noob, Math or Array Issue?

Finally figured it out on my own with some modifications...

Controller:
  def show
    @food = Food.find(params[:id])
    @fiber = Array.new(@food.fiber.to_f, 4)
    @points = (@food.calories.to_f / 50) + (@food.fat.to_f / 12) -
((@fiber.min.to_f) / 5)
  end

View:
<p><b>Points:</b> <%= @points.round %></p>

Seems to produce the results I want...any better way would be welcome.

On Jul 14, 2:18 pm,
"jeremy.b...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org"
<jeremy.b...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> I goofed up...when the minimum of @fiber = 0, I get the nasty
> message...not when @points = 0.  I apologize.
>
> On Jul 14, 2:15 pm,
"jeremy.b...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org"
<jeremy.b...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> wrote:
>
> > Let''s say that below is the math for figuring out a unit in a
popular
> > diet program:
>
> >     @fiber = Array.new(@food.fiber, 4)
> >     @points = (@food.calories / 50) + (@food.fat / 12) - (@fiber.min /
> > 5)
>
> > And that for personal use, I''m creating a system to keep
track of
> > these units on a daily basis and I''m simply rendering @points
in the
> > following manner in my view:
>
> >    <p><b>Points:</b> <%= @points %></p>
>
> > But when @points equals 0, I get the nasty message:
>
> >  NoMethodError in FoodsController#show
>
> > You have a nil object when you didn''t expect it!
> > The error occurred while evaluating nil./
>
> > What would one do to make it OK to have a 0 instead of causing it to
> > evaluate nil?

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Matthew Rudy

2007-Jul-14 19:29 UTC

head link

Re: Rails Noob, Math or Array Issue?

hmm,
I don''t understand you Array.new statement

Array.new(x, 4) just returns an array with x lots of 4
Array.new(7, 4)  = [4,4,4,4,4,4,4]
Array.new(7.3,4) = [4,4,4,4,4,4,4]

@fiber = Array.new(x, 4)
@fiber.min = 4

whatever the x is.

I''d put all the code in the model

class Food
    def points
        value = 0
        value += (calories.to_f / 50) if calories
        value += (     fat.to_f / 12) if fat
        value += (   fiber.to_f /  5) if fiber
        return value
    end
end

and just call @food.points in your view

the problem you were having at the start was because one of these 
attributes (calories, fat or fiber)
was nil for the model,
I suggest setting :default => 0 in the migration.
Then you can get rid of the "if"s in the code above


jeremy.bise-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
wrote:> Finally figured it out on my own with some modifications...
> 
> Controller:
>   def show
>     @food = Food.find(params[:id])
>     @fiber = Array.new(@food.fiber.to_f, 4)
>     @points = (@food.calories.to_f / 50) + (@food.fat.to_f / 12) -
> ((@fiber.min.to_f) / 5)
>   end
> 
> View:
> <p><b>Points:</b> <%= @points.round %></p>
> 
> Seems to produce the results I want...any better way would be welcome.
> 
> On Jul 14, 2:18 pm,
"jeremy.b...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org"
<jeremy.b...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

-- 
Posted via http://www.ruby-forum.com/.

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jeremy.bise-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

2007-Jul-17 13:48 UTC

head link

Re: Rails Noob, Math or Array Issue?

What I need is something that returns the minimum of food.fiber or 4,
whichever is lower.  I appreciate your help--I''m just a programming
idiot to begin with and even moreso at Ruby/Rails.

On Jul 14, 3:29 pm, Matthew Rudy
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:> hmm,
> I don''t understand you Array.new statement
>
> Array.new(x, 4) just returns an array with x lots of 4
> Array.new(7, 4)  = [4,4,4,4,4,4,4]
> Array.new(7.3,4) = [4,4,4,4,4,4,4]
>
> @fiber = Array.new(x, 4)
> @fiber.min = 4
>
> whatever the x is.
>
> I''d put all the code in the model
>
> class Food
>     def points
>         value = 0
>         value += (calories.to_f / 50) if calories
>         value += (     fat.to_f / 12) if fat
>         value += (   fiber.to_f /  5) if fiber
>         return value
>     end
> end
>
> and just call @food.points in your view
>
> the problem you were having at the start was because one of these
> attributes (calories, fat or fiber)
> was nil for the model,
> I suggest setting :default => 0 in the migration.
> Then you can get rid of the "if"s in the code above
>
>
>
> jeremy.b...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org wrote:
> > Finally figured it out on my own with some modifications...
>
> > Controller:
> >   def show
> >     @food = Food.find(params[:id])
> >     @fiber = Array.new(@food.fiber.to_f, 4)
> >     @points = (@food.calories.to_f / 50) + (@food.fat.to_f / 12) -
> > ((@fiber.min.to_f) / 5)
> >   end
>
> > View:
> > <p><b>Points:</b> <%= @points.round
%></p>
>
> > Seems to produce the results I want...any better way would be welcome.
>
> > On Jul 14, 2:18 pm,
"jeremy.b...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org"
<jeremy.b...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>
> --
> Posted viahttp://www.ruby-forum.com/.

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Rails - Jul 2007 - Rails Noob, Math or Array Issue?

Rails Noob, Math or Array Issue?

Re: Rails Noob, Math or Array Issue?

Re: Rails Noob, Math or Array Issue?

Re: Rails Noob, Math or Array Issue?

Re: Rails Noob, Math or Array Issue?