Hi folks,
The book describes DAL's _after_insert() callback
<http://www.web2py.com/books/default/chapter/29/06/the-database-abstraction-layer#callbacks-on-record-insert--delete-and-update>
as:
The caveat is that depending on the functionality, the callback has
> different signature.
> This is best explained via some examples.
> >>> db.define_table('person',Field('name'))
> >>> def pprint(*args): print args
> >>> db.person._before_insert.append(lambda f: pprint(f))
> >>> db.person._after_insert.append(lambda f,id: pprint(f,id)) # WRONG
> SIGNATURE?
> >>> db.person._before_update.append(lambda s,f: pprint(s,f))
> >>> db.person._after_update.append(lambda s,f: pprint(s,f))
> >>> db.person._before_delete.append(lambda s: pprint(s))
> >>> db.person._after_delete.append(lambda s: pprint(s))
> Here f is a dict of fields passed to insert or update, id is the id of
> the newly inserted record, s is the Set object used for update or delete.
> >>> db.person.insert(name='John')
> ({'name': 'John'},)
> ({'name': 'John'}, 1) # WRONG EXAMPLE?
However, I believe (at least in web2py 2.9.12) the first parameter in
_after_insert() is NOT a dict, but a Row object. Because, my web2py app
uses the following code in db.py, trying to send out a validation email to
new registrated user:
def customized_email_verification(row, row_id):
>
db(db.auth_user.id==row_id).update(registration_key="a random string")
> # I need this because my users are not registered from web UI
db.commit() # commit BEFORE the time consuming email action, otherwise
> a parallel requests could cause duplicated record in DB?!
auth.settings.mailer.send(to=row["email"], subject="Hi",
*message=customized_message
> % row*)
> db.auth_user._after_insert.append(customized_email_verification)
and it ends up with a very confusing error as:
TypeError: format requires a mapping
Finally I located that line and changed it into:
... customized_message % row.as_dict()
and then it works.
So I am asking for your confirmation and suggest to fix the book
accordingly.
A followup question. The reason I need my clumsy
customized_email_verification() in the first place, is because I seemingly
have to do db.commit() BEFORE the time consuming email sending job.
Otherwise I saw some randomly duplicated records in my auth_user table. I
don't know the exact reason but my guess is, the tools.py's define_tables()
uses IS_NOT_IN_DB() validators which only work in web2py level, but does
NOT define any "unique=True" in the DB level. Is this considered as a
defect? Think about this sequence.
Now: the first user creation request is validated but by default not yet
committed, and now sending email which will likely take 2 seconds
Now + 1 second: Somehow the client could resent same request. This request
also passes validation, because there is no duplication in DB so far.
Now + 2 second: The email for request #1 has been sent. And record #1 is
committed into DB.
Now + 3 second: The email for request #2 has been sent. And duplicated
record #2 is committed into DB.
How can I improve such pattern? Thanks!
Regards,
Ray
--
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- http://web2py.com/book (Documentation)
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