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lib/Alzabo/Runtime/RowCursor.pm  view on Meta::CPAN

package Alzabo::Runtime::RowCursor;

use strict;
use vars qw($VERSION);

use Alzabo::Exceptions;
use Alzabo::Runtime;

use Params::Validate qw( :all );
Params::Validate::validation_options( on_fail => sub { Alzabo::Exception::Params->throw( error => join '', @_ ) } );

use base qw( Alzabo::Runtime::Cursor );

$VERSION = 2.0;

use constant NEW_SPEC => { statement => { isa => 'Alzabo::DriverStatement' },
                           table => { isa => 'Alzabo::Runtime::Table' },
                         };

sub new
{
    my $proto = shift;
    my $class = ref $proto || $proto;

    my %p = validate( @_, NEW_SPEC );

    my $self = bless { %p,
                       count => 0,
                     }, $class;

    return $self;
}

sub next
{
    my $self = shift;

    my $row;

    # This loop is intended to allow the end caller to ignore rows
    # that can't be created because they're not in the table.
    #
    # For example, imagine that query in the statement is looking at
    # table 'foo' to get PK values for table 'bar'.  If table 'foo'
    # has a record indicating that there is a row in 'bar' where PK ==
    # 1 but no such row actually exists then we want to skip this.
    #
    # If they really want to know we do save the exception.
    until ( defined $row )
    {
        my @row = $self->{statement}->next;

        last unless @row && grep { defined } @row;

        my %hash;
        my @pk = $self->{table}->primary_key;
        @hash{ map { $_->name } @pk } = @row[0..$#pk];

        my %prefetch;
        if ( (my @pre = $self->{table}->prefetch) && @row > @pk )
        {
            @prefetch{@pre} = @row[$#pk + 1 .. $#row];
        }

        $row = $self->{table}->row_by_pk( @_,
                                          pk => \%hash,
                                          prefetch => \%prefetch,
                                          %{ $self->{row_params} },
                                        );
    }