Autoincrement field

[ceriox]

hi all,
i need an autoincremented unic numeric field for make a ticket system
how i can do it?

thanks for help

[Alexandre Andrade]

by default, web2py creates a 'id' field, it is autoincremented.

2010/1/15 ceriox <cer...@gmail.com>

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Atenciosamente

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=========================
Alexandre Andrade
Hipercenter.com

[Thadeus Burgess]

Field('mysecondaryid', 'integer', default=db.table.mysecondaryid + 1)

should work.

-Thadeus

[mdipierro]

No it will not.

On Jan 15, 10:32 am, Thadeus Burgess <thade...@thadeusb.com> wrote:
> Field('mysecondaryid', 'integer', default=db.table.mysecondaryid + 1)
>
> should work.
>
> -Thadeus
>

> On Fri, Jan 15, 2010 at 7:14 AM, Alexandre Andrade <alexandrema...@gmail.com

>
> > wrote:
> > by default, web2py creates a 'id' field, it is autoincremented.
>
> > 2010/1/15 ceriox <cer...@gmail.com>
>
> >> hi all,
> >> i need an autoincremented unic numeric field for make a ticket system
> >> how i can do it?
>
> >> thanks for help
>
> >> --
>
> >> You received this message because you are subscribed to the Google Groups
> >> "web2py-users" group.
> >> To post to this group, send email to web...@googlegroups.com.
> >> To unsubscribe from this group, send email to

> >> web2py+un...@googlegroups.com<web2py%2Bunsu...@googlegroups.com>

> >> .
> >> For more options, visit this group at
> >>http://groups.google.com/group/web2py?hl=en.
>
> > --
> > Atenciosamente
>
> > --
> > =========================
> > Alexandre Andrade
> > Hipercenter.com
>
> > --
> > You received this message because you are subscribed to the Google Groups
> > "web2py-users" group.
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> > To unsubscribe from this group, send email to

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[Thadeus Burgess]

Duh, my bad

Here follow this post

http://groups.google.com/group/web2py/browse_thread/thread/7c801d48d456871f/7263df4d37211f53?lnk=gst&q=31704#7263df4d37211f53

-Thadeus

To unsubscribe from this group, send email to web2py+un...@googlegroups.com.

[ceriox]

thanks for the reply but i'm not a good web2py programmer ... i
writing my first real app
you can write the code for my request? (i can't understand the post of
your link)

[Thadeus Burgess]

max_id= db(db.table.autonumber>1).select(db.table.autonumber, #
select all records, and only pull the autonumber column
orderby=~db.table.autonumber, #
descending sort on the autonumber, (highest first)
limitby=(0,1) # limit the query and
only select the first record
).first().autonumber # pull the first record
from the web2py rows object, and get its autonumber member

db.table.autonumber.default = max_id + 1 # Set the table default as
the last autonumber and incremented by one.
db.table.autonumber.writable = False

form = crud.create(db.table)

-Thadeus

[matclab]

Hello,
I'm finding this message in a thread from February...

I thought that autoincremented field would guaranty unicity in the
table.
I'm afraid the provided solution would allow two record to have the
same autonumber field (think about an access from two users at the
same time).
I guess the autoincrement should be done on the DAL or database side,
inside a transaction....

What do you think about it ?

[mdipierro]

What is wrong with the default id field that web2py creates for every
table?

[Iceberg]

I guess the point here is, generally speaking, what is a secure way to
make two or more subsequent DAL operations are performed without race
condition. Is a kind of lock needed? An example to describe the
problem (but not solving it):

def index():
with a_lock_to_prevent_concurrent_requests: # but how?
latest_data = db(...).select(...)
new_data = do_something_with( latest_data )
db.mytable.insert( new_data )

See also: http://groups.google.com/group/web2py/browse_frm/thread/35be6bba0c02eab0#

[Mathieu Clabaut]

I guess that one may want some more constraints on the autoincrement field. For example, it shall begin at 100  for ecample.

It may be because for example, before the application exists some paper records where made which were referenced by number < 100)

For such a problem, I've set up with:

Field('ref_number', compute=lambda r: r['id'] + 100)

Which I hope would eliminate the race solution as it is calculate upon insertion in the database... Is it the case ?

-Mathieu

[mdipierro]

yes

On May 28, 3:44 am, Mathieu Clabaut <mathieu.clab...@gmail.com> wrote:
> I guess that one may want some more constraints on the autoincrement field.
> For example, it shall begin at 100  for ecample.
> It may be because for example, before the application exists some paper
> records where made which were referenced by number < 100)
>
> For such a problem, I've set up with:
>
> Field('ref_number', compute=lambda r: r['id'] + 100)
>
> Which I hope would eliminate the race solution as it is calculate upon
> insertion in the database... Is it the case ?
>
> -Mathieu
>

> > web2py+un...@googlegroups.com<web2py%2Bunsu...@googlegroups.com>
> > .

[szimszon]

Hi!

I wonder if somebody could help me.

The

definet_table('sometable',
    Field('otherid', compute=lambda r: r['id'])
)

doesn't work for me. :( Sould it work? With other than r['id'] it's working.

Version 2.4.1-alpha.2+timestamp.2013.01.27.10.24.17

[Alec Taylor]

Which DB are you using BTW?

Because if you're using something like MySQL; they have inbuilt
autoincrement fields which would be much better to utilise than what
we provide in the DAL.

Maybe we should have an 'autoincrement' field, like we have a 'datetime' field?

Gracefully degrade to a lambda if there isn't native autoincrement support.

> --
>
>
>

[szimszon]

postgresql Version: 8.4.12-0squeeze1 (producttion - not tested)
postgresql Version: 9.1.7-0ubuntu12.10 (dev)

I need somethink like:

Field('otherid','string', compute=lambda r: 'SOMETHING%s%s' % (
    str(datetime.date.today()),
    str(r['id'])))

>> > > web2py+un...@googlegroups.com<web2py%2Bunsubscribe@googlegroups.com>

[szimszon]

I'm definitively for an auto-increment field like datetime anyway :-D

2013. január 28., hétfő 15:48:24 UTC+1 időpontban Alec Taylor a következőt írta:

>> > > web2py+un...@googlegroups.com<web2py%2Bunsubscribe@googlegroups.com>

[szimszon]

Something about this issue? Should it work?

> > web2py+un...@googlegroups.com<web2py%2Bunsubscribe@googlegroups.com>

[szimszon]

The really ugly thing is that compute can silently fail and you could end up with None in the db table cell :(

[szimszon]

Some other issue:

db:

import datetime
db.define_table('sometable',
    Field('otherid',
          compute=lambda r: 'SPPRIME%s' % (
                                    datetime.date.today().strftime('%y%m%d'))
)

If I insert a db row from modules

current.db.sometable.insert()

The new record has otherid==None :(

[Massimo Di Pierro]

Please open a ticket about this.

[szimszon]

http://code.google.com/p/web2py/issues/detail?id=1307

and

http://code.google.com/p/web2py/issues/detail?id=1308

Tnx.

[Alec Taylor]

On Wed, Jan 30, 2013 at 1:15 AM, Massimo Di Pierro
<massimo....@gmail.com> wrote:
> Please open a ticket about this.

http://code.google.com/p/web2py/issues/detail?id=1311

[Alec Taylor]

"Optionally you can define a field of `type='id'` and web2py will use
this field as auto-increment id field. This is not recommended except
when accessing legacy database tables. With some limitation, you can
also use different primary keys and this is discussed in the section
on "Legacy databases and keyed tables"."
— http://web2py.com/books/default/chapter/29/06#DAL,-Table,-Field