Rails - Jul 2007 - validations of "type" when using Single Table Inheritance

Sorry if I''m just dumbing out, but is there a reason that when using
Single Table Inheritance Rails doesn''t really validate the
"type"
field or provide some mechanism to do so? seems like a good way to
corrupt a database. Because the "type" is also a special attribute, I
had to resort to an ugly hack like:

  class ActiveRecord::Base
    def type_attr
      self[:type]
    end
    def self.validates_type(options={})
      validates_inclusion_of   :type_attr, options
    end
  end

so that I could write:

  class Fruit < ActiveRecord::Base

    validates_type   :allow_nil => true,
                            :in => %w{ Apple }   # could be dynamic
subclass_of but make faster!

(obviously this could also have been put on the derived class)

Thanks!


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I''d dare to say the reason "type" can''t be validated
is that it
inherently has to exist.

After all, the "type" is exactly the name of the class on which
you''re
calling "create"

if the "type" doesn''t exist,
then you can''t be trying to save it.

Jaime Cham wrote:
> Sorry if I''m just dumbing out, but is there a reason that when
using
> Single Table Inheritance Rails doesn''t really validate the
"type"
> field or provide some mechanism to do so? seems like a good way to
> corrupt a database. Because the "type" is also a special
attribute, I
> had to resort to an ugly hack like:
> 
>   class ActiveRecord::Base
>     def type_attr
>       self[:type]
>     end
>     def self.validates_type(options={})
>       validates_inclusion_of   :type_attr, options
>     end
>   end
> 
> so that I could write:
> 
>   class Fruit < ActiveRecord::Base
> 
>     validates_type   :allow_nil => true,
>                             :in => %w{ Apple }   # could be dynamic
> subclass_of but make faster!
> 
> (obviously this could also have been put on the derived class)
> 
> Thanks!

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

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Yes, although it could be changed manually (unlikely) or injected from
cgi parameters, which is what the validations are supposed to prevent,
no?

On Jul 9, 6:07 am, Matthew Rudy
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
> I''d dare to say the reason "type" can''t be
validated is that it
> inherently has to exist.
>
> After all, the "type" is exactly the name of the class on which
you''re
> calling "create"
>
> if the "type" doesn''t exist,
> then you can''t be trying to save it.
>
>
>
> JaimeCham wrote:
> > Sorry if I''m just dumbing out, but is there a reason that
when using
> > Single Table Inheritance Rails doesn''t really validate the
"type"
> > field or provide some mechanism to do so? seems like a good way to
> > corrupt a database. Because the "type" is also a special
attribute, I
> > had to resort to an ugly hack like:
>
> >   class ActiveRecord::Base
> >     def type_attr
> >       self[:type]
> >     end
> >     def self.validates_type(options={})
> >       validates_inclusion_of   :type_attr, options
> >     end
> >   end
>
> > so that I could write:
>
> >   class Fruit < ActiveRecord::Base
>
> >     validates_type   :allow_nil => true,
> >                             :in => %w{ Apple }   # could be dynamic
> > subclass_of but make faster!
>
> > (obviously this could also have been put on the derived class)
>
> > Thanks!
>
> --
> Posted viahttp://www.ruby-forum.com/.

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