+sub get_stock {
+ my ($self, %params) = @_;
+
+ return undef unless $self->id;
+
+ my $query = 'SELECT SUM(qty) FROM inventory WHERE parts_id = ?';
+ my @values = ($self->id);
+
+ if ( $params{bin_id} ) {
+ $query .= ' AND bin_id = ?';
+ push(@values, $params{bin_id});
+ }
+
+ if ( $params{warehouse_id} ) {
+ $query .= ' AND warehouse_id = ?';
+ push(@values, $params{warehouse_id});
+ }
+
+ if ( $params{shippingdate} ) {
+ die unless ref($params{shippingdate}) eq 'DateTime';
+ $query .= ' AND shippingdate <= ?';
+ push(@values, $params{shippingdate});
+ }
+
+ my ($stock) = selectrow_query($::form, $self->db->dbh, $query, @values);
+
+ return $stock || 0; # never return undef
+};
+
+