I might be very wrong on this, but it's actually correct that way.
None is NOT a value (it is a const identifier) and hence you cannot/
should not compare it by value or use logic operators on it. The same
goes for databases' NULL. Take a look for example at mysql, when you
do 'WHERE id = NULL' there, it will also hurt you - you should do 'id
IS NULL' just as 'id is None' in Python. None evaluates to false under
certain conditions so it might work depending on the expression but
you'll do yourself a favor if you do not rely on this if it is part of
a logical expression.
For your specific example that would mean something along the lines of
db.( ~ (db.Orders.special==True))
If I'm cardinally wrong, please correct me.
On Dec 12, 12:59 pm, Iceberg <iceb...@21cn.com> wrote:
> Hi there,
>
> I encounter a not-so-intuitive behavior when search in boolean field,
> named
>
> Giving the definition:
> SQLField('special', 'boolean', default=False)
> And bear in mind that there are THREE kinds of value in this field:
> True, False, and ""(None)!
>
> When I search:
> db(db.Orders.special==True).select()
> it works like a charm.
>
> When I search:
> db(db.Orders.special!=True).select()
> it equals to:
> db(db.Orders.special==False).select()
> but not equals to:
> db((db.Orders.special==False)|(db.Orders.special==None)).select()
>
> Do I have to use the last form to select all non-True records? Is this
> an intended design, or a unexpected flaw?
>
> Thanks in advance.
> Iceberg
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