I don't have a blog to post this on, and I just tried something which
turned out to be insanely useful. I thought other Sequel users might really
enjoy if they hadn't realized it already, so I hope it's ok to post this
here :)
Let's say you have a plain old ruby object that is associated with one of
your models, perhaps a mortgage interest calculator or an address or
something like that. You might use `composition` in this case to generate a
ruby object from value columns in the database. However, if you've got a
composition object that has a lot of inputs, or potentially variable
inputs, this can bloat your table with a ton columns or even a bunch of
optional and often null columns.
Well, if the object can be converted to/from a hash, and you're using
Postgres, you could make a beautiful serialization just using the hstore
extension.
Assuming you have a model `PriceQuote`, and a complicated business logic
object `PriceCalculator`, you could add `column :calculator, :hstore` to
your `price_quotes` table, and then do this:
class PriceQuote < Sequel::Model
def calculator=(price_calculator)
super(price_calculator.to_hash)
end
def calculator
PriceCalculator.new(super)
end
end
Now when you want to use these...
price_quote = PriceQuote.first
price_quote.calculator.class #=> PriceCalculator
other_quote = PriceQuote.new(...)
other_quote.calculator = PriceCalculator.new(...)
other_quote.save
other_quote.reload
other_quote.calculator #=> #<PriceCalculator:0x00512314 ... >
other_quote.calculator.do_some_calculation #=> yes this works :)
Jeremy, I just have to say that Sequel is super awesome. Thanks for giving
the world this fantastic library!
Andrew
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