Hello all,
I've been thinking about implementing a module that takes a DAL table
definition and generates a class object from that definition. The purpose of
this is to use those automatically generated classes in the controllers
instead of accessing the DAL directly. Eg: Creating an instance of that
class could make an insertion in the db transparently; setting attributes on
that instance triggers db updates, etc..
One important feature is that every table Row is mapped to an instance of
some class and this layer is completely opaque, i.e. it can't expose any
Rows/Row/Field objects to the client.
A more concrete example of whats being pursued:
-----------------
db.define_table( "Person", Field('name') )
db.define_table( "Dog", Field("name"), Field("Owner",db.Person) )
*createClass*(db.Person)
*createClass*(db.Dog)
#and now you can do:
p = Person("John") #selects person with name="John", possibly
throwing exception or creating such a record (have to weigh the pros and
cons)
johns_dogs = p.dog_list #johns_dogs is a *list* of *Dog* instances
johns_dogs[0].name #returns name of one of the john's dogs.
johns_dogs[0].name = "new name" #updates this dogs name in db
-----------------
I've had some success a this, namely, made a function that takes a Rows
object and returns a list of Storage instances where each storage has the
same attributes as the corresponding Row fields and, whenever the value of a
Row's Field is a Sql.Set, it *.selects()* it and continues recursively until
everything is converted into a big tree of Storage instances.
This is where I ask for some help. Ideally I don't want to convert every Row
into a Storage, I'd like a Row of table *Product* (e.g.) to be converted
into an instance of class *Product* (which was automatically generated when
table Product was defined). Yet, I do not know of *an easy way to get the
Table from which a specific Row came from. Is it possible without major
hacks in the DAL?*
Also, since you're at it, what do you think about this? My motivation is
that it gets tiring to be defining helper functions to make the controller
code simpler and then be constantly updating those helper functions whenever
the model changes.
Thanks a lot in advance,
Tiago
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