Rails - Mar 2008 - On Update, how can I validate that an attribute has not being already set?

Hi

I have a boolean attribute on a model ... user_approved ... that I
wish to apply some validation to upon update ...

The business rule is "You cannot update this model to user_approved if
it already has been" .... but I am not sure if I can do this using the
normal rails validations?

For example, using update_attributes, how do I tell that they have
requested to update this field as opposed to updating another?

Anyone have any elegant solutions?

Thanks
Shane
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shane wrote:
> The business rule is "You cannot update this model to user_approved if
> it already has been" .... but I am not sure if I can do this using the
> normal rails validations?
You probably want to add this to the model:

attr_protected :user_approved

This will prevent the attribute from being set by #update_attributes and 
so will protect you from someone sending their own form content to your 
update actions and sneaking in a change.

You can then override the #user_approved= method in the model to do the 
validation.  When attributes are set, their #attribute= methods are 
called to set the values.  You can override these as you like to 
validate the input and check the current value before making any 
changes.

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The business rule is fail.

If it''s already set to true, why does updating it true matter?


On Mon, Mar 3, 2008 at 9:32 AM, shane
<shane.mingins-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> Hi
>
> I have a boolean attribute on a model ... user_approved ... that I
> wish to apply some validation to upon update ...
>
> The business rule is "You cannot update this model to user_approved if
> it already has been" .... but I am not sure if I can do this using the
> normal rails validations?
>
> For example, using update_attributes, how do I tell that they have
> requested to update this field as opposed to updating another?
>
> Anyone have any elegant solutions?
>
> Thanks
> Shane
> >
>

-- 
Ryan Bigg
http://www.frozenplague.net
Feel free to add me to MSN and/or GTalk as this email.

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