[Alzabo] Quick way to count rows in a RowCursor?

[Ken Williams <ken@ma...>]

Hi,

Is there a quick way to count the number of rows returned by a 
RowCursor?  Currently I'm doing something like this:

  # assoc_links() follows a linking table
  my @rows = $object->assoc_links->all_rows;
  my $count = @rows;

Two things aren't ideal here - first, all_rows() has to go through the 
work of creating objects for all the rows it returns, when all I need 
is a count.  Second, I have to store those objects in an array, which I 
throw away (actually, '$count = $object->assoc_links->all_rows;' looks 
like it would work fine, but isn't documented).

Any chance of adding a method like $row_cursor->count_rows(), or 
something, that counts rows which have *not* been fetched yet?

  -Ken

Re: [Alzabo] Quick way to count rows in a RowCursor?

[Dave Rolsky <autarch@ur...>]

On Thu, 1 May 2003, Ken Williams wrote:

> Is there a quick way to count the number of rows returned by a
> RowCursor?  Currently I'm doing something like this:
>
>   # assoc_links() follows a linking table
>   my @rows = $object->assoc_links->all_rows;
>   my $count = @rows;
>
> Two things aren't ideal here - first, all_rows() has to go through the
> work of creating objects for all the rows it returns, when all I need
> is a count.  Second, I have to store those objects in an array, which I
> throw away (actually, '$count = $object->assoc_links->all_rows;' looks
> like it would work fine, but isn't documented).
>
> Any chance of adding a method like $row_cursor->count_rows(), or
> something, that counts rows which have *not* been fetched yet?

Sure, that could be done.  It'd still have to fetch all the data from the
database, though.


-dave

/*=======================
House Absolute Consulting
 http://www.houseabsolute.com
=======================*/

[Alzabo] problem with post_insert

[Fen Labalme <fen@co...>]

Is post_insert known to work?  Does it get the new, inserted object?

I ask as after a Member table gets updated a post_insert gets called to
update an Action table reflecting a new member.  But $self->member_id_c
inserts a zero (0) into the Action table, despite the fact that the new
Member table row just inserted a row with member_id set to (say) 7.

Or maybe I'm doing something wrong - I'm still getting used to Alzabo.
Code is below.

Thanks,
Fen


package CPV::Data::Table::Member;

sub post_insert
{
    my $self = shift;

    my $row = $Schema->ActionList_t->one_row (
        where => [ $Schema->ActionList_t->action_c, '=', 'join' ] );

    $Schema->Action_t->insert (
        values => { member_id     => $self->member_id_c,
                    actionList_id => $row->actionList_id,
                    points        => $row->points } );
}

-- 
Fen Labalme, Director of Technology, Coalition for Progressive Values
   Never doubt that a small group of thoughtful, committed citizens
   can change the world. Indeed, it's the only thing that ever has. 
                                   -- Margaret Mead 

Re: [Alzabo] problem with post_insert

[Dave Rolsky <autarch@ur...>]

On Thu, 1 May 2003, Fen Labalme wrote:

> Is post_insert known to work?  Does it get the new, inserted object?

Yes, but not as it's sole argument.

> sub post_insert
> {
>     my $self = shift;
>
>     my $row = $Schema->ActionList_t->one_row (
>         where => [ $Schema->ActionList_t->action_c, '=', 'join' ] );
>
>     $Schema->Action_t->insert (
>         values => { member_id     => $self->member_id_c,
>                     actionList_id => $row->actionList_id,
>                     points        => $row->points } );
> }

The problem is that a post_insert hook needs to work like this:

 sub post_insert
 {
      my $table = shift;
      my %p = @_;

      my $row = delete $p{row};
      my %insert_values = %p;

      ...
 }

This interface is a little off though, now that I like at it closely.
Sticking the row in the same hash of values as was inserted is bad, just
in case someone names a column "row".


-dave

/*=======================
House Absolute Consulting
 http://www.houseabsolute.com
=======================*/

Re: [Alzabo] problem with post_insert

[Dave Rolsky <autarch@ur...>]

On Fri, 2 May 2003, Dave Rolsky wrote:

> The problem is that a post_insert hook needs to work like this:
>
>  sub post_insert
>  {
>       my $table = shift;
>       my %p = @_;
>
>       my $row = delete $p{row};
>       my %insert_values = %p;
>
>       ...
>  }

Ooops, that should be

  sub post_insert
  {
       my $table = shift;
       my $p = shift;

       my $row = delete $p->{row};
       my %insert_values = %$p;

       ...
  }

-dave

/*=======================
House Absolute Consulting
 http://www.houseabsolute.com
=======================*/

[Alzabo] function or select using aggregate function?

[Fen Labalme <fen@co...>]

When I use select in the code below, the first line returns undef (despite
the fact that matching where clause lines exist with points values set) and
the second returns the correct number.

But if I follow the documentation 
http://www.alzabo.org/docs/Alzabo.mhtml#Using%20SQL%20functions
and change the select to function, I get this error:

The following parameter was passed in the call to Alzabo::Runtime::Table::_select_sql but was not listed in the validation options: function
/usr/local/share/perl/5.6.1/Alzabo/Runtime/Table.pm: 9
/usr/local/share/perl/5.6.1/Alzabo/Runtime/Table.pm: 339
/usr/local/share/perl/5.6.1/Alzabo/Runtime/Table.pm: 339
/usr/local/share/perl/5.6.1/Alzabo/Runtime/Table.pm: 310
/x/web/cpv/demo/activist_points.mas: 29
...

What does this mean?  I'm guessing my syntax is incorrect - can someone give
me a pointer as to how to fix?

Thanks,
Fen
---


$points = $Schema->Action_t->function (
    select => SUM( $Schema->Action_t->points_c ),
    where  => [ $Schema->Action_t->member_id_c, '=', $Member->member_id ]
    ) || 0;

$total = $Schema->Action_t->function(
    select => SUM( $Schema->Action_t->points_c ));

Re: [Alzabo] function or select using aggregate function?

[Dave Rolsky <autarch@ur...>]

On Fri, 1 May 2003, Fen Labalme wrote:

> The following parameter was passed in the call to Alzabo::Runtime::Table::_select_sql but was not listed in the validation options: function
> /usr/local/share/perl/5.6.1/Alzabo/Runtime/Table.pm: 9
> /usr/local/share/perl/5.6.1/Alzabo/Runtime/Table.pm: 339
> /usr/local/share/perl/5.6.1/Alzabo/Runtime/Table.pm: 339
> /usr/local/share/perl/5.6.1/Alzabo/Runtime/Table.pm: 310
> /x/web/cpv/demo/activist_points.mas: 29
> ...
>
> What does this mean?  I'm guessing my syntax is incorrect - can someone give
> me a pointer as to how to fix?

It means you passed a parameter named "function" to some Alzabo method.

> $points = $Schema->Action_t->function (
>     select => SUM( $Schema->Action_t->points_c ),
>     where  => [ $Schema->Action_t->member_id_c, '=', $Member->member_id ]
>     ) || 0;
>
> $total = $Schema->Action_t->function(
>     select => SUM( $Schema->Action_t->points_c ));

Both of these should work, but are you _sure_ this is the code you're
executing?

And what version of Alzabo are you using?


-dave

/*=======================
House Absolute Consulting
 http://www.houseabsolute.com
=======================*/

Re: [Alzabo] function or select using aggregate function?

[Fen Labalme <fen@co...>]

Dave Rolsky <autarch@...> writes:

> On Fri, 1 May 2003, Fen Labalme wrote:
> 
> > The following parameter was passed in the call to Alzabo::Runtime::Table::_select_sql but was not listed in the validation options: function
> > /usr/local/share/perl/5.6.1/Alzabo/Runtime/Table.pm: 9
> > /usr/local/share/perl/5.6.1/Alzabo/Runtime/Table.pm: 339
> > /usr/local/share/perl/5.6.1/Alzabo/Runtime/Table.pm: 339
> > /usr/local/share/perl/5.6.1/Alzabo/Runtime/Table.pm: 310
> > /x/web/cpv/demo/activist_points.mas: 29
> > ...
> >
> > What does this mean?  I'm guessing my syntax is incorrect - can someone give
> > me a pointer as to how to fix?
> 
> It means you passed a parameter named "function" to some Alzabo method.
> 
> > $points = $Schema->Action_t->function (
> >     select => SUM( $Schema->Action_t->points_c ),
> >     where  => [ $Schema->Action_t->member_id_c, '=', $Member->member_id ]
> >     );
>
> Both of these should work, but are you _sure_ this is the code you're
> executing?

Yes, but my note was confusing.  $points is undef after the code above.  But
when I use 'function' instead of 'select' as in the snippet below, I get the 
error message referencing Alzabo/Runtime/Table.pm

############ from /x/web/cpv/demo/activist_points.mas
$points = $Schema->Action_t->function (  ####### activist_points.mas, line 29 
    function => SUM( $Schema->Action_t->points_c ),
    where  => [ $Schema->Action_t->member_id_c, '=', $Member->member_id ]
    );

############ from /usr/local/share/perl/5.6.1/Alzabo/Runtime/Table.pm
sub function
{
    my $self = shift;
    my %p = @_;

    my $sql = $self->_select_sql(%p);  ####### line 310

    my $method =
        UNIVERSAL::isa( $p{select}, 'ARRAY' ) && @{ $p{select} } > 1 ? 'rows' : 'column';

    $sql->debug(\*STDERR) if Alzabo::Debug::SQL;
    print STDERR Devel::StackTrace->new if Alzabo::Debug::TRACE;

    return $self->schema->driver->$method( sql => $sql->sql,
					   bind => $sql->bind );
}

sub _select_sql
{
    my $self = shift;

    my %p = validate( @_, { select => { type => SCALAR | ARRAYREF | OBJECT },
			    where  => { type => ARRAYREF | OBJECT,
					optional => 1 },
			    order_by => { type => ARRAYREF | HASHREF | OBJECT,
					  optional => 1 },
			    group_by => { type => ARRAYREF | HASHREF | OBJECT,
					  optional => 1 },
                            having   => { type => ARRAYREF,
                                          optional => 1 },
			    limit => { type => SCALAR | ARRAYREF,
				       optional => 1 },
			  } );

Not sure if I'm reading this corrctly, but there appears to be no validate
option in _select_sql for function, which is what the error complains about.
And the reason I'm trying to use 'function' is that's what the doc suggests:
http://www.alzabo.org/docs/Alzabo.mhtml#Using%20SQL%20functions

> And what version of Alzabo are you using?

Alzabo 0.72, Perl 5.6.1, MySql 3.23.52, Debian Linux (testing) kernel 2.4.19

Thanks,
Fen

Re: [Alzabo] Mea Culpa! function or select using aggregate function?

[Fen Labalme <fen@co...>]

Mea Culpa!  My mistake!

Please ignore previous message - I found the error in my table structure.

Thanks again for your help and apologies for taking your time.

(Though I *am* still confused by the documentation at
http://www.alzabo.org/docs/Alzabo.mhtml#Using%20SQL%20functions
that reads
 my $max = $table->function( function => MAX( $table->column('budget') ),
                             where => [ $table->column('country'), '=', 'USA' ] );
Perhaps the second "function" ought to be a "select"?)

I love Alzabo!

Fen
===


Fen Labalme <fen@...> writes:
...
<erroneously>

Re: [Alzabo] function or select using aggregate function?

[Dave Rolsky <autarch@ur...>]

On Fri, 2 May 2003, Fen Labalme wrote:

> Yes, but my note was confusing.  $points is undef after the code above.  But
> when I use 'function' instead of 'select' as in the snippet below, I get the
> error message referencing Alzabo/Runtime/Table.pm
>
> ############ from /x/web/cpv/demo/activist_points.mas
> $points = $Schema->Action_t->function (  ####### activist_points.mas, line 29
>     function => SUM( $Schema->Action_t->points_c ),
>     where  => [ $Schema->Action_t->member_id_c, '=', $Member->member_id ]
>     );

That's cause you're supposed to call the parameter "select" regardless of
which method you call.

> Not sure if I'm reading this corrctly, but there appears to be no validate
> option in _select_sql for function, which is what the error complains about.
> And the reason I'm trying to use 'function' is that's what the doc suggests:
> http://www.alzabo.org/docs/Alzabo.mhtml#Using%20SQL%20functions

That's cause the guy who wrote the docs wasn't paying enough attention ;)

There is no "function" parameter.


-dave

/*=======================
House Absolute Consulting
 http://www.houseabsolute.com
=======================*/