This solution work well at least with Postgres.
Richard
On Mon, Jul 11, 2011 at 10:34 AM, Richard Vézina <
ml.richard.vez...@gmail.com> wrote:
> Just to close this thread nicely, here the solution I found (thanks to
> Bruno for concatenation :)
>
> import datetime
> now = datetime.datetime.today()
> db.define_table('person',
> Field('name'),
> Field('registration_stamp', 'datetime', default=now))
> recent = db(db.person.registration_stamp>now-datetime.timedelta(10))
> db.person.name.requires = IS_NOT_IN_DB(recent, 'person.name') # From the
> book
>
> db.define_table('umultiple',
> Field('a','string'),
> Field('b','string'),
> Field('ab', unique=True, compute=lambda r: r.a + r.b)) # Multiple
> columns UNIQUE constraint like SQL : ALTER TABLE ref_fnaregistry ADD
> CONSTRAINT test_unique UNIQUE (a, b);
>
> db.umultiple.a.requires =
> IS_NOT_IN_DB(db(db.umultiple.ab==str(request.vars.a)+str(request.vars.b)),
> 'umultiple.a')
> db.umultiple.b.requires =
> IS_NOT_IN_DB(db(db.umultiple.ab==str(request.vars.a)+str(request.vars.b)),
> 'umultiple.b') # Multiple columns UNIQUE constraint validators repeated over
> each fields that have been declared unique
>
>
> So, as Bruno said the concatenate field 'ab' that use unique=True is a DB
> validation and serve to assign UNIQUE check constaint to this column... Then
> to be sure not get a ticket you need to add a validator to the fields that
> has to be unique (form level validation). Here we want 'a' and 'b' to be
> unique. So, we use the versatility of the IS_NOT_IN_DB() validator... It can
> check if a value is in a given table or in a given set here we are passing a
> set like this :
> db(db.umultiple.ab==str(request.vars.a)+str(request.vars.b)). To make sure
> the user is going to understand that there is many fields responsible to the
> error, we replicate the validator for all the fields that are
> concatenated... But only one is enough to ensure there is no duplicated
> value in the db.
>
> I attach a little app...
>
> Richard
>
> On Sat, Jul 2, 2011 at 2:25 PM, Nick Arnett <nick.arn...@gmail.com> wrote:
>
>>
>>
>> On Fri, Jul 1, 2011 at 1:20 AM, Bruno Rocha <rochacbr...@gmail.com>wrote:
>>
>>> Db.define_table('foo',Field('a'),Field('b'), Field('ab',unique=True,
>>> compute=lambda r: r.a + r.b))
>>>
>> This failed for me with sqlite and I see from other discussions that the
>> same is true with Django - sqlite throws an error that it cannot create a
>> unique field.
>>
>> However, it seems to work fine with MySQL; it did create a unique index on
>> the column. I wasn't really planning to use sqlite, anyway, just thought
>> I'd keep things simpler at first. I just switched to MySQL now and it's
>> working fine.
>>
>> Thanks for the help.
>>
>> Nick
>>
>
>
