Unfortunately there is no simple way to achieve multi-column unique
costraints in web2py.
Aside from your implementation, you can use a third column that stores
a composite key, say "%s_$$$_%s" % (key1, key2), that you can compute
and set as unique.
Something like (not tested):
db.define_table('t9n_mytable',
Field('record', 'references records_table'),
Field('language', length=2, notnull=True),
Field('unique_col_costraint',
compute=lambda row: "%s_$$$_%s" % (row['record'],
row['language']),
unique=True)
)
On 20 Nov, 15:17, ~redShadow~ <[email protected]> wrote:
> I just developed a way to quickly handle translations of table records,
> that works this way:
>
> Assuming we have a table name 'mytable' with three fields ('field0',
> 'field1' and 'field2'), it creates an exact copy of the original table
> (named 't9n_mytable', containing all the original fields plus a
> 'language' field, containin language code, and a 'record' field that is
> a reference to mytable).
>
> Now, I want to be sure there are no duplicate translations, and way to
> do so would be to create an unique index on ``(record, language)``, but
> it looks like there is no straight-forward way to do that in web2py..
>
> For the moment, I solved using this code, but it doesn't look great.. is
> there a better way to do this?
>
> Code::
>
> _table_existed = ('t9n_mytable' in db.tables)
>
> ## Here, define the table...
>
> if not _table_existed:
> import urlparse
> dbtype = urlparse.urlparse(db._uri).scheme
> if dbtype == 'sqlite':
> db.executesql('CREATE UNIQUE INDEX'
> ' IF NOT EXISTS unique_record_language'
> ' ON t9n_mytable (record, language);')
> elif dbtype == 'mysql':
> db.executesql('CREATE UNIQUE INDEX'
> ' unique_record_language'
> ' ON t9n_mytable (record, language);')
> elif dbtype == 'pgsql':
> db.executesql('CREATE UNIQUE INDEX'
> ' unique_record_language'
> ' ON t9n_mytable (record, language);')
> else:
> pass
>
> --
> Samuele ~redShadow~ Santi
> ----------------------------------------------------------------
> redshadow[at]hackzine.org - redshadowhack[at]gmail.com
>
> Blog:http://hackzine.org
>
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