[Rails] Active Record Question

[Aled Davies]

This worked perfectly :). I was trying to do something similar with the 
code that I had but was getting problems with the class not finding 
methods and the like. I suspect that was down my lack of Ruby 
knowledge.

Having solved this I can say I will be trying Rails for this project :).

	Thanks

	Aled

--
Aled Davies <awd at well.com>

On Nov 10, 2004, at 4:00 AM, rails-request at lists.rubyonrails.org wrote:
> Message: 5
> Date: Wed, 10 Nov 2004 11:27:30 +0000
> From: Tom Ward <tom.ward at gmail.com>
> Subject: Re: [Rails] Active Record Question
> To: rails at lists.rubyonrails.org
> Message-ID: <e9b09d890411100327253a8dc1 at mail.gmail.com>
> Content-Type: text/plain; charset=US-ASCII
>
> I'm new to both Ruby and Rails, so someone may well have a better
> suggestion, but here's how I'd do this:-
>
> module UUIDHelper
>   def before_create()
>     sql = "SELECT UUID()"
>     record = connection.select_one(sql, " #{name} UUID generated")
>     self.id = record['UUID()']
>   end
> end
>
> class ModelClass < ActiveRecord::Base
>   include UUIDHelper
> end
>
> Including the module should add the methods defined as a mixin, while
> before_create is a callback method called before creation (a bit
> cleaner than overriding create).
>
> http://api.rubyonrails.org/classes/ActiveRecord/Callbacks.html
>
> Hope this is helpful,
>
> Tom Ward
>
> On Tue, 9 Nov 2004 23:05:51 -0800, Aled Davies <awd at well.com> wrote:
>> (I posted this at ruby-forum, but I figured that I should also try
>> here):
>>
>> I'm new to Ruby and Rails and am evaluating using Ruby on Rails as the
>> framework for an asset management project I'm working on and have run
>> into an issue with Active Record that I'm wondering if there is anyway
>> around.
>>
>> The issue is this, one of the requirements I have is that all asset
>> primary keys must be UUIDs. MySQL 4.1 allows the generation of UUIDs
>> using 'SELECT UUID()' so to implement support for using a UUID as a
>> primary key, I added the following methods to my model class:
>>
>> Code:
>>
>>    def uuid()
>>       sql = "SELECT UUID()"
>>       record = connection.select_one(sql, " #{name} UUID generated")
>>       return record['UUID()']
>>    end
>>
>>    # Override create to insert the identifier prior to creation.
>>    def create
>>       self.id = uuid();
>>       super
>>    end
>>
>> As this code will be common to all models in the application I figured
>> that I could move this into a super-class (that extends
>> ActiveRecord::Base) that sub-classes can extend to get this
>> functionality for free. The problem is that ActiveRecord tries apply
>> the single-table inheritance rule to the model and tries to insert a
>> type in the table (which fails because it isn't in the model).
>>
>> And so the question is this. Is there anyway of having a custom
>> super-class for your models which won't trigger the single-table
>> inheritance rule ?
>>
>> (while I realize that I can just add a 'type' field to the database, 
>> it
>> seems like the wrong thing to have to do in this case. I also tried
>> using a Module, but this seemed not to work, but I suspect that was
>> down to my newness with Ruby)
>>
>>         Thanks
>>
>>         Aled
>>
>> --
>> Aled Davies <awd at well.com>
>>
>>
>> _______________________________________________
>> Rails mailing list
>> Rails at lists.rubyonrails.org
>> http://lists.rubyonrails.org/mailman/listinfo/rails
>>
>>
>>
>>
>
>
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> End of Rails Digest, Vol 2, Issue 14
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