Re: [PhillyOnRails] ActiveRecord::new() and default table values

[Evan <eweaver@gmail.com>]

You can force a specific primary key by adding an id writer method to
your model:

   def id= n; write_attribute :id, n; end

Then after instantiating the object with .new(hash), you can assign
.id= the new id. Then you can save the record and it will go in with
the id you want. (At least, that's how I worked around the problem in
my own code).

I don't know why your "kind" attribute isn't getting saved properly, though.

Evan


On 10/18/06, Cassius Rosenthal <cassius@xmodulation.com> wrote:
> Interesting approach.  This breaks filters because the YAML object uses
> strings instead of symbols to hash the attributes.  Substituting strings
> into filter functions [is ugly but] does solve the problem of :kind in
> the example below overriding the table default; however, the id for the
> object still is not preserved.  In this case, it defaults to the
> postgres sequence.  So this approach still doesn't work.
>
> This may be obvious, but building on my example below, the sql:
> "INSERT INTO products VALUES (42,'apple','fruit');"
> works perfectly, and is the sql that I expect/wish to be generated by Rails.
>
> Any other ideas?
>
> Thanks!
> -Cassius
>
>
> Chris wrote:
> > Try products[0].clone rather than creating a new object.
> >
> > Cassius Rosenthal wrote:
> >> This is one of those questions where I knew how to do what I want to,
> >> but I can't for the life of me remember how to do it.  I should know
> >> this, but I just can't seem to find the answer from The Brain (ie.,
> >> googling didn't help).
> >> Say I have a model Product.  I create the table as follows:
> >> [code]
> >>  create_table :products, :force => true do |t|
> >>    t.column :name, :string
> >>    t.column :kind, :string, :default=>"pizza"
> >>  end
> >> [/code]
> >>
> >> I then load a product from a fixture:
> >> [code]
> >> products=YAML::load(foo.yml)
> >> [/code]
> >> #products[0].attributes=>
> >> {:id=>"42",  :name=>"apple", :kind=>"fruit"}
> >> So far, so good.  Note the id of 42, which is important because this
> >> object relates to another model, and I want to preserve the primary
> >> keys.
> >>
> >> Then I instantiate a new ActiveRecord from this data:
> >> [code]
> >> @product=Product.new(products[0].attributes)
> >> [code]
> >> #@products=>
> >> {:id=>"1",  :name=>"apple", :kind=>"pizza"}
> >> Ack!  ActiveRecord used the table defaults instead of the attributes
> >> that I sent to the object.  How do I override this behavior?
> >>
> >> Thanks!
> >> -Cassius
> >> _______________________________________________
> >> talk mailing list
> >> talk@phillyonrails.org
> >> http://lists.phillyonrails.org/mailman/listinfo/talk
> >>
> >
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--
Evan Weaver
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