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Dean

2007-Feb-06 18:58 UTC

Default values in join model

I have a has_many :through and I would like to take values from one
side and put them in the join model.  Perhaps some code would be more
clear.

class Recipe < AR::Base
  has_many :fermentable_ingredients
  has_many :fermentables, :through => :fermentable_ingredients
end

class Fermentable < AR::Base
  has_many :fermentable_ingredients
  has_many :recipes, :through => :fermentable_ingredients
end

classFermentableIngredient < AR::Base
  belongs_to :recipe
  belongs_to :fermentable
end

Simple enough.  When I assign a fermentable to a
fermentable_ingredienet, I would like to populate the
fermentable_ingredient with values in fermentable.  Something like
this:

def fermentable=(f)
  self.potential = f.potential if potential.nil?
  self.color = f.color if color.nil?
  super
end

I know this doesn''t work because the call to super fails.

Is there a clean way to do this?

Thanks,
--Dean
http://blog.brewsession.com/


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Dan Manges

2007-Feb-06 20:37 UTC

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Re: Default values in join model

On Feb 6, 1:58 pm, "Dean"
<dean.brund...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> class Recipe < AR::Base
>   has_many :fermentable_ingredients
>   has_many :fermentables, :through => :fermentable_ingredients
> end
>
> class Fermentable < AR::Base
>   has_many :fermentable_ingredients
>   has_many :recipes, :through => :fermentable_ingredients
> end
>
> classFermentableIngredient < AR::Base
>   belongs_to :recipe
>   belongs_to :fermentable
> end
>
> Simple enough.  When I assign a fermentable to a
> fermentable_ingredienet, I would like to populate the
> fermentable_ingredient with values in fermentable.  Something like
> this:
Will this work?

class FermentableIngredient
  before_save :copy_from_fermentable

  protected
    def copy_from_fermentable
        if self.fermentable
          self.potential ||= fermentable.potential
          self.color ||= fermentable.color
        end
    end
end

Dan Manges


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Dean

2007-Feb-06 21:17 UTC

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Re: Default values in join model

On Feb 6, 12:37 pm, "Dan Manges"
<daniel.man...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Will this work?
>
> class FermentableIngredient
>   before_save :copy_from_fermentable
>
>   protected
>     def copy_from_fermentable
>         if self.fermentable
>           self.potential ||= fermentable.potential
>           self.color ||= fermentable.color
>         end
>     end
> end
>
> Dan Manges
Thanks for the suggestion, but I want to do it before saving.  Like
here:

class FermentableIngredientsController < ApplicationController
  def new
    @fermentable_ingredient = FermentableIngredient.new
    @fermentable_ingredient.fermentable Fermentable.find(
params[:fermentable_id] )
    render
  end
end

That way the form fields for @fermentable_ingredient will be
automatically filled out.  As it is I have to call an extra method
before render to transfer the values.

--Dean


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Dan Manges

2007-Feb-06 23:27 UTC

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Re: Default values in join model

On Feb 6, 4:17 pm, "Dean"
<dean.brund...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Thanks for the suggestion, but I want to do it before saving.
Try this:

classFermentableIngredient < AR::Base
  belongs_to :recipe
  belongs_to :fermentable

  fermentable_with_copy=(f)
    self.potential ||= f.potential
    self.color ||= f.color
    fermentable_without_copy=f
  end
  alias_method :fermentable_without_copy=, :fermentable  alias_method
:fermentable=, :fermentable_with_copyend

Dan Manges


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Dean

2007-Feb-07 00:52 UTC

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Re: Default values in join model

> On Feb 6, 4:17 pm, "Dean"
<dean.brund...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> Try this:
>
> classFermentableIngredient < AR::Base
>   belongs_to :recipe
>   belongs_to :fermentable
>
>   fermentable_with_copy=(f)
>     self.potential ||= f.potential
>     self.color ||= f.color
>     fermentable_without_copy=f
>   end
>   alias_method :fermentable_without_copy=, :fermentable>   alias_method
:fermentable=, :fermentable_with_copy> end
>
> Dan Manges
That is *really* close, except it does not assign the fermentable to
the ingredient.

./script/console>> i = FermentableIngredient.new
=> #<FermentableIngredient...>>> i.fermentable = Fermentable.find(1)=> #<Fermentable:...
"potential"=>"1.037"}>>> i.potential
=> 1.037>> i.fermentable.potentialNoMethodError: You have a nil object when you didn''t expect it!
The error occurred while evaluating nil.potential
        from (irb):5
>> i.fermentable=> nil

Looks like this should work from the ruby-doc on alias_method
http://www.ruby-doc.org/core/classes/Module.html#M001706

  alias_method :orig_fermentable=, :fermentable  def fermentable=(f)
    self.potential ||= f.potential
    self.color ||= f.color
    orig_fermentable = f
  end

But it still does not assign the fermentable to the
fermentable_ingredient.

--Dean
http://blog.brewsession.com/

On Feb 6, 3:27 pm, "Dan Manges"
<daniel.man...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:


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Dean

2007-Feb-07 00:56 UTC

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Re: Default values in join model [SOLVED]

And the answer is:

  alias_method :orig_fermentable=, :fermentable
  def fermentable=(f)
    self.potential ||= f.potential
    self.color ||= f.color
    self.orig_fermentable = f
  end

Thanks to Dan for the help

--Dean
http://blog.brewsession.com/


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Rails - Feb 2007 - Default values in join model

Default values in join model

Re: Default values in join model

Re: Default values in join model

Re: Default values in join model

Re: Default values in join model

Re: Default values in join model [SOLVED]