No, these would be a chainable set of helper functions that act on a
Rows object (just like the new first and last functions). Most of them
would take functions or lambdas as arguments that return boolean
values. They could be used to do complex calculations. Here are a
couple mock command:
rows = db().select(db.logs.ALL) # cached select
weekend = rows.where(lambda x: x.posted.day in range(5,6)).skip
(current_page * page_size).take(page_size)
if weekend.any():
...
...or...
def file_exists(row):
return os.path.exists(row.filepath)
uploads = db().select(db.uploads.ALL) # cached select
valid = uploads.where(file_exists)
Does that make sense?
On Sep 11, 8:55 pm, mdipierro <[email protected]> wrote:
> The point of the DAL i generate SQL so that queries are executed by
> the database. Are you saying that those operations should be executed
> by web2py instead on the returned items? Why?
>
> On Sep 11, 7:06 pm, "mr.freeze" <[email protected]> wrote:
>
> > >>2) you can now do:
> > >>row = db(db.mytable.id>0).select().first()
> > >>row = db(db.mytable.id>0).select().last()
> > >>and row is None if no records are selected.
>
> > Here is a list of other functions that may be of interest (I borrowed
> > these from .net extension methods). Some of these won't make sense
> > for web2py but others may be handy if implemented. Some may already
> > be implemented:
>
> > all - returns True if all elements in a sequence match a condition
> > any - return True if the sequence contains any elements
> > average - returns the average of a sequence of elements
> > contains - returns True is the sequence contains a given element
> > distinct - returns unique elements for a sequence
> > intersect - produces the set of common elements between two sequences
> > min - returns the lowest element in a sequence
> > max - returns the highest element in a sequence
> > single - returns the only element of a sequence and throws an error if
> > there is not exactly one element.
> > skip - bypass a specified contiguous number of elements in a sequence
> > skip_while - bypass elements of a sequence that match a condition and
> > return the remaining elements
> > take - returns a contiguous number of elements in a sequence
> > take_while - returns a contiguous number of elements that match a
> > sequence
> > where - returns elements in a sequence that match a condition
> > except - produces the difference between two sequences
> > union - produces the union of two sequences
> > reverse - reverses the order of elements in a sequence
>
> > On Sep 11, 12:12 am, mdipierro <[email protected]> wrote:
>
> > > I have made some changes to the code in trunk:
>
> > > 1) Since tonight I attended a presentation about how SQLAlchemy can do
> > > on delete cascade in SQLite even if SQLite does not support it, I
> > > implemented this feature in web2py too. There is nothing you have to
> > > do it now there by default. For example:
>
> > > db=DAL('sqlite://test.db')
> > > db.define_table('a',Field('name'))
> > > db.define_table('b',Field('a',db.a,ondelete='CASCADE'),Field('name'))
> > > db.a.insert(name='xxx1')
> > > db.a.insert(name='xxx2')
> > > db.a.insert(name='xxx3')
> > > db.a.insert(name='xxx4')
> > > db.b.insert(a=2,name='yyy1') #(1)
> > > db.b.insert(a=2,name='yyy2') #(1)
> > > db.b.insert(a=3,name='yyy3')
> > > db(db.a.id==2).delete()
> > > for row in db(db.b.a==2).select(): print row # prints nothing as it
> > > should
>
> > > Notice ondelete='CASCADE' is default.
>
> > > 2) you can now do:
>
> > > row = db(db.mytable.id>0).select().first()
> > > row = db(db.mytable.id>0).select().last()
>
> > > and row is None if no records are selected.
>
> > > 3) I fixed the problem with the memory leak reported by zahariash
>
> > > 4) I refactored some code in main.py, compileapp.py and globals.py.
> > > This should make the code cleaner. Hopefully I did not break it.
> > > Please give it a try.
>
> > > Massimo
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