Robby Russell wrote:
> On Tue, Sep 30, 2008 at 9:13 PM, Anthony E.
> <[EMAIL PROTECTED]> wrote:
>> Something like this:
>> @book.price = $20.00
>>
>> @book.save()
>> @stats.save()
>
> Anthony,
>
> Is Book the only model that you'll be doing this for? ...or are there
> other models that will use this historical log of prices?
>
> There's a few options here. One, you could add method to be called by
> after_save to check the price previously stored with the new one... if
> they are different... add a new entry to the historical log.
>
> Another option is to not store prices in the Book model and only in
> another table called something like BookPrice.
>
> book has_many book_prices
>
> Then you can scope book_prices for current to do something like:
>
> book.book_prices.current.price # => get the current price
>
> book.book_prices.each { |book_price| ... } # => iterate through all
> book prices
>
> Anyhow, there's a few options to throw your way. Good luck!
>
> Cheers,
> Robby
>
>
>
Thanks Robby.
I will be doing this for one model for now, perhaps others down the
road.
The "Book" model has numeric attributes that I want to save into a
"statistics" table so I can draw a line-graph over time from it.
Other attributes would be archived as well.
Its sounds to be a before_update would give me access to the current
price. And I don't want to keep the current price in a stats table
because that table will eventually grow and slow down the regular query.
book
----------
id
title
price
edition
year
stats
----------
id
book_id
price
edition
year
created_at
updated_at
Ideally sans-rails the stats table would be populated with a trigger
when the book table is updated.
There book will definitely "has_many :stats" but I don't really want
that association to be queried every time I get a regular book object,
only when I build the stats page.
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