From: Philipp Meier <meier@...>
Date: 2002-09-21T04:06:39+09:00
Subject: Re: Mapping Db Fields to Class Attributes


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On Sat, Sep 21, 2002 at 12:04:55AM +0900, David.Stagner@mpls.frb.org wrote:
> One thing i CAN tell you is to write a code generator to read the table=
=20
> DDLs and crank out wrapper classes that way (as the Pragmatic Programmers=
=20
> would tell you, too).  If you want to map better variable names over the=
=20
> original database names, write them up as text metadata and feed that int=
o=20
> your code generator.  [...]

With ruby's reflection you can avoid a code generator but create dynamic
proxys. Pseudo code follows:

class DBObject
	def intialize(table, id_col, id_value)
		stm =3D DB.prepare("select * from #{table} where ? =3D ?")
		row =3D stm.execute(id_col, id_value).fetch
		@data =3D {}
		row.each_pair do |attr, value|
			@data[attr] =3D value
			self.type.module_eval %q{
				def #{attr}
					return @data[:#{attr}]
				end
			end
		end
	end
end

-billy.

--=20
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   eL=F6sungen       89077 Ulm                     Fax: +49-731-399 499-9

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