pypgsql-users

Re: [Pypgsql-users] Re: PgBoolean

[<vze...@ve...>]

Thanks for the python tips. I guess it shows that I am new to the language :-)

Unfortunately, I still can't seem to get this right. I tried this:

if retval:
    print "YES"
else:
    print "NO"

When executed, this prints out "YES" when the statement "print retval" prints either

[<PgBoolean instance at 0x401c890c: Value: True>]

- or -

[<PgBoolean instance at 0x401c8900: Value: False>]

What am I doing wrong?

Re: [Pypgsql-users] Re: PgBoolean

[<Bil...@mu...>]

vze...@ve... wrote:
> Thanks for the python tips. I guess it shows that I am new to the language :-
> )
> 
> Unfortunately, I still can't seem to get this right. I tried this:
> 
> if retval:
>     print "YES"
> else:
>     print "NO"
> 
> When executed, this prints out "YES" when the statement "print retval" prints
>  either
> 
> [<PgBoolean instance at 0x401c890c: Value: True>]
> 
> - or -
> 
> [<PgBoolean instance at 0x401c8900: Value: False>]
> 
> What am I doing?

The problem is that you are testing the PgResultSet object, not the PgBoolean.  The PgResultSet will always test true unless it's empty.

Try doing the following:

    if retval[0]:
        print "Yes"
    else:
        print "No"

Here is an example:

    >>> c = PgSQL.connect()
    >>> cu = c.cursor()
    >>> cu.execute("select 'f'::bool as myBool")
    >>> rs = cu.fetchone()
    >>> type(rs)
    <type 'instance'>
    >>> rs.__class__
    <class pyPgSQL.PgSQL.PgResultSetConcreteClass at 805acdc>
    >>> 
    >>> rs
    [<PgBoolean instance at bfd7e110: Value: False>]
    >>> myBool = rs['myBool'] # or rs.myBool or rs[0]
    >>> myBool
    f
    >>> print myBool
    f
    >>> repr(myBool)
    '<PgBoolean instance at bfd7e110: Value: False>'
    >>> if myBool:
    ...     print "Yes"
    ... else:
    ...     print "No"
    ... 
    No
    >>>

-- 
____       | Billy G. Allie    | Domain....: Bil...@mu...
|  /|      | 7436 Hartwell     | MSN.......: B_G...@em...
|-/-|----- | Dearborn, MI 48126|
|/  |LLIE  | (313) 582-1540    |

Re: [Pypgsql-users] Re: PgBoolean

[Gerhard H. <ger...@gm...>]

* vze...@ve... <vze...@ve...> [2002-11-20 20:18 -0600]:
> Thanks for the python tips. I guess it shows that I am new to the language
> :-)
> 
> Unfortunately, I still can't seem to get this right. I tried this:
> 
> if retval: print "YES" else: print "NO"
> 
> When executed, this prints out "YES" when the statement "print retval" prints
> either
> 
> [<PgBoolean instance at 0x401c890c: Value: True>]
> 
> - or -
> 
> [<PgBoolean instance at 0x401c8900: Value: False>]
> 
> What am I doing wrong?

I don't know. It works just fine here:

gerhard@gargamel:/tmp$ python
Python 2.2.2 (#1, Oct 18 2002, 03:24:30) 
[GCC 2.95.4 20020320 [FreeBSD]] on freebsd4
Type "help", "copyright", "credits" or "license" for more information.
>>> from pyPgSQL import PgSQL
>>> db = PgSQL.connect(); cursor = db.cursor()
>>> cursor.execute("select b from test where b is true")
>>> res = cursor.fetchone()
>>> res.b
t
>>> repr(res.b)
'<PgBoolean instance at 0x2826202c: Value: True>'
>>> res.b == 1
1
>>> res.b == 0
0
>>> if res.b:
...   print "true"
... else:
...   print "false"
... 
true
>>> cursor.execute("select b from test where b is false")
>>> res = cursor.fetchone()
>>> res.b
f
>>> repr(res.b)
'<PgBoolean instance at 0x28262020: Value: False>'
>>> if res.b:
...   print "true"
... else:
...   print "false"
... 
false
>>> 

If you still can't get it to work, could you please post a complete code
section that shows the problem?

-- Gerhard