Query returned more than one row
-In this case, you should be using L</first> or L</find> instead, or if you really
+In this case, you should be using L</next> or L</find> instead, or if you really
know what you are doing, use the L</rows> attribute to explicitly limit the size
of the resultset.
+This method will also throw an exception if it is called on a resultset prefetching
+has_many, as such a prefetch implies fetching multiple rows from the database in
+order to assemble the resulting object.
+
=back
=cut
my $attrs = $self->_resolved_attrs_copy;
+ if (keys %{$attrs->{collapse}}) {
+ $self->throw_exception(
+ 'single() can not be used on resultsets prefetching has_many. Use find( \%cond ) or next() instead'
+ );
+ }
+
if ($where) {
if (defined $attrs->{where}) {
$attrs->{where} = {
$attrs->{_virtual_order_by} = [ $self->result_source->primary_columns ];
- my $collapse = $attrs->{collapse} || {};
-
+ $attrs->{collapse} ||= {};
if ( my $prefetch = delete $attrs->{prefetch} ) {
$prefetch = $self->_merge_attr( {}, $prefetch );
my $join_map = $self->_joinpath_aliases ($attrs->{from}, $attrs->{seen_join});
my @prefetch =
- $source->_resolve_prefetch( $prefetch, $alias, $join_map, $prefetch_ordering, $collapse );
+ $source->_resolve_prefetch( $prefetch, $alias, $join_map, $prefetch_ordering, $attrs->{collapse} );
push( @{ $attrs->{select} }, map { $_->[0] } @prefetch );
push( @{ $attrs->{as} }, map { $_->[1] } @prefetch );
push( @{ $attrs->{order_by} }, @$prefetch_ordering );
+ $attrs->{_collapse_order_by} = \@$prefetch_ordering;
}
+
if (delete $attrs->{distinct}) {
$attrs->{group_by} ||= [ grep { !ref($_) || (ref($_) ne 'HASH') } @{$attrs->{select}} ];
}
- $attrs->{collapse} = $collapse;
-
# if both page and offset are specified, produce a combined offset
# even though it doesn't make much sense, this is what pre 081xx has
# been doing
}
sub _select_args {
- my ($self, $ident, $select, $condition, $attrs) = @_;
+ my ($self, $ident, $select, $where, $attrs) = @_;
my $sql_maker = $self->sql_maker;
- $sql_maker->{for} = delete $attrs->{for};
-
- my $order = { map
- { $attrs->{$_} ? ( $_ => $attrs->{$_} ) : () }
- (qw/order_by group_by having _virtual_order_by/ )
- };
-
-
- my $bind_attrs = {};
-
my $alias2source = $self->_resolve_ident_sources ($ident);
+ # calculate bind_attrs before possible $ident mangling
+ my $bind_attrs = {};
for my $alias (keys %$alias2source) {
my $bindtypes = $self->source_bind_attributes ($alias2source->{$alias}) || {};
for my $col (keys %$bindtypes) {
}
}
- # This would be the point to deflate anything found in $condition
- # (and leave $attrs->{bind} intact). Problem is - inflators historically
- # expect a row object. And all we have is a resultsource (it is trivial
- # to extract deflator coderefs via $alias2source above).
- #
- # I don't see a way forward other than changing the way deflators are
- # invoked, and that's just bad...
-
- my @args = ('select', $attrs->{bind}, $ident, $bind_attrs, $select, $condition, $order);
+ my @limit;
if ($attrs->{software_limit} ||
$sql_maker->_default_limit_syntax eq "GenericSubQ") {
$attrs->{software_limit} = 1;
# MySQL actually recommends this approach. I cringe.
$attrs->{rows} = 2**48 if not defined $attrs->{rows} and defined $attrs->{offset};
- push @args, $attrs->{rows}, $attrs->{offset};
+
+ if ($attrs->{rows} && keys %{$attrs->{collapse}}) {
+ ($ident, $select, $where, $attrs)
+ = $self->_adjust_select_args_for_limited_prefetch ($ident, $select, $where, $attrs);
+ }
+ else {
+ push @limit, $attrs->{rows}, $attrs->{offset};
+ }
+ }
+
+###
+ # This would be the point to deflate anything found in $where
+ # (and leave $attrs->{bind} intact). Problem is - inflators historically
+ # expect a row object. And all we have is a resultsource (it is trivial
+ # to extract deflator coderefs via $alias2source above).
+ #
+ # I don't see a way forward other than changing the way deflators are
+ # invoked, and that's just bad...
+###
+
+ my $order = { map
+ { $attrs->{$_} ? ( $_ => $attrs->{$_} ) : () }
+ (qw/order_by group_by having _virtual_order_by/ )
+ };
+
+
+ $sql_maker->{for} = delete $attrs->{for};
+
+ return ('select', $attrs->{bind}, $ident, $bind_attrs, $select, $where, $order, @limit);
+}
+
+sub _adjust_select_args_for_limited_prefetch {
+ my ($self, $from, $select, $where, $attrs) = @_;
+
+ if ($attrs->{group_by} and @{$attrs->{group_by}}) {
+ $self->throw_exception ('Prefetch with limit (rows/offset) is not supported on resultsets with a group_by attribute');
}
- return @args;
+
+ $self->throw_exception ('Prefetch with limit (rows/offset) is not supported on resultsets with a custom from attribute')
+ if (ref $from ne 'ARRAY');
+
+ # separate attributes
+ my $sub_attrs = { %$attrs };
+ delete $attrs->{$_} for qw/where bind rows offset/;
+ delete $sub_attrs->{$_} for qw/for collapse select order_by/;
+
+ my $alias = $attrs->{alias};
+
+ # create subquery select list
+ my $sub_select = [ grep { $_ =~ /^$alias\./ } @{$attrs->{select}} ];
+
+ # bring over all non-collapse-induced order_by into the inner query (if any)
+ # the outer one will have to keep them all
+ if (my $ord_cnt = @{$attrs->{order_by}} - @{$attrs->{_collapse_order_by}} ) {
+ $sub_attrs->{order_by} = [
+ @{$attrs->{order_by}}[ 0 .. ($#{$attrs->{order_by}} - $ord_cnt - 1) ]
+ ];
+ }
+
+
+ # mangle the head of the {from}
+ my $self_ident = shift @$from;
+
+ my %join_info = map { $_->[0]{-alias} => $_->[0] } (@$from);
+
+ my (%inner_joins);
+
+ # decide which parts of the join will remain on the inside
+ #
+ # this is not a very viable optimisation, but it was written
+ # before I realised this, so might as well remain. We can throw
+ # away _any_ branches of the join tree that are:
+ # 1) not mentioned in the condition/order
+ # 2) left-join leaves (or left-join leaf chains)
+ # Most of the join ocnditions will not satisfy this, but for real
+ # complex queries some might, and we might make some RDBMS happy.
+ #
+ #
+ # since we do not have introspectable SQLA, we fall back to ugly
+ # scanning of raw SQL for WHERE, and for pieces of ORDER BY
+ # in order to determine what goes into %inner_joins
+ # It may not be very efficient, but it's a reasonable stop-gap
+ {
+ # produce stuff unquoted, so it can be scanned
+ my $sql_maker = $self->sql_maker;
+ local $sql_maker->{quote_char};
+
+ my @order_by = (map
+ { ref $_ ? $_->[0] : $_ }
+ $sql_maker->_order_by_chunks ($sub_attrs->{order_by})
+ );
+
+ my $where_sql = $sql_maker->where ($where);
+
+ # sort needed joins
+ for my $alias (keys %join_info) {
+
+ # any table alias found on a column name in where or order_by
+ # gets included in %inner_joins
+ # Also any parent joins that are needed to reach this particular alias
+ for my $piece ($where_sql, @order_by ) {
+ if ($piece =~ /\b$alias\./) {
+ $inner_joins{$alias} = 1;
+ }
+ }
+ }
+ }
+
+ # scan for non-leaf/non-left joins and mark as needed
+ # also mark all ancestor joins that are needed to reach this particular alias
+ # (e.g. join => { cds => 'tracks' } - tracks will bring cds too )
+ #
+ # traverse by the size of the -join_path i.e. reverse depth first
+ for my $alias (sort { @{$join_info{$b}{-join_path}} <=> @{$join_info{$a}{-join_path}} } (keys %join_info) ) {
+
+ my $j = $join_info{$alias};
+ $inner_joins{$alias} = 1 if (! $j->{-join_type} || ($j->{-join_type} !~ /^left$/i) );
+
+ if ($inner_joins{$alias}) {
+ $inner_joins{$_} = 1 for (@{$j->{-join_path}});
+ }
+ }
+
+ # construct the inner $from for the subquery
+ my $inner_from = [ $self_ident ];
+ if (keys %inner_joins) {
+ for my $j (@$from) {
+ push @$inner_from, $j if $inner_joins{$j->[0]{-alias}};
+ }
+
+ # if a multi-type join was needed in the subquery ("multi" is indicated by
+ # presence in {collapse}) - add a group_by to simulate the collapse in the subq
+ for my $alias (keys %inner_joins) {
+
+ # the dot comes from some weirdness in collapse
+ # remove after the rewrite
+ if ($attrs->{collapse}{".$alias"}) {
+ $sub_attrs->{group_by} = $sub_select;
+ last;
+ }
+ }
+ }
+
+ # generate the subquery
+ my $subq = $self->_select_args_to_query (
+ $inner_from,
+ $sub_select,
+ $where,
+ $sub_attrs
+ );
+
+ # put it back in $from
+ unshift @$from, { $alias => $subq };
+
+ # This is totally horrific - the $where ends up in both the inner and outer query
+ # Unfortunately not much can be done until SQLA2 introspection arrives
+ #
+ # OTOH it can be seen as a plus: <ash> (notes that this query would make a DBA cry ;)
+ return ($from, $select, $where, $attrs);
}
sub _resolve_ident_sources {
+++ /dev/null
-# Test to ensure we get a consistent result set wether or not we use the
-# prefetch option in combination rows (LIMIT).
-use strict;
-use warnings;
-
-use Test::More;
-use lib qw(t/lib);
-use DBICTest;
-
-plan skip_all => 'fix pending';
-#plan tests => 4;
-
-my $schema = DBICTest->init_schema();
-my $no_prefetch = $schema->resultset('Artist')->search(
- undef,
- { rows => 3 }
-);
-
-my $use_prefetch = $schema->resultset('Artist')->search(
- undef,
- {
- prefetch => 'cds',
- rows => 3
- }
-);
-
-is($no_prefetch->count, $use_prefetch->count, '$no_prefetch->count == $use_prefetch->count');
-is(
- scalar ($no_prefetch->all),
- scalar ($use_prefetch->all),
- "Amount of returned rows is right"
-);
-
-
-
-my $artist_many_cds = $schema->resultset('Artist')->search ( {}, {
- join => 'cds',
- group_by => 'me.artistid',
- having => \ 'count(cds.cdid) > 1',
-})->first;
-
-
-$no_prefetch = $schema->resultset('Artist')->search(
- { artistid => $artist_many_cds->id },
- { rows => 1 }
-);
-
-$use_prefetch = $schema->resultset('Artist')->search(
- { artistid => $artist_many_cds->id },
- {
- prefetch => 'cds',
- rows => 1
- }
-);
-
-my $prefetch_artist = $use_prefetch->first;
-my $normal_artist = $no_prefetch->first;
-
-is(
- $prefetch_artist->cds->count,
- $normal_artist->cds->count,
- "Count of child rel with prefetch + rows => 1 is right"
-);
-is (
- scalar ($prefetch_artist->cds->all),
- scalar ($normal_artist->cds->all),
- "Amount of child rel rows with prefetch + rows => 1 is right"
-);
--- /dev/null
+# Test to ensure we get a consistent result set wether or not we use the
+# prefetch option in combination rows (LIMIT).
+use strict;
+use warnings;
+
+use Test::More;
+use Test::Exception;
+use lib qw(t/lib);
+use DBICTest;
+
+plan tests => 9;
+
+my $schema = DBICTest->init_schema();
+
+
+my $no_prefetch = $schema->resultset('Artist')->search(
+ undef,
+ { rows => 3 }
+);
+
+my $use_prefetch = $schema->resultset('Artist')->search(
+ [ # search deliberately contrived
+ { 'artwork.cd_id' => undef },
+ { 'tracks.title' => { '!=' => 'blah-blah-1234568' }}
+ ],
+ {
+ prefetch => 'cds',
+ join => { cds => [qw/artwork tracks/] },
+ rows => 3,
+ order_by => { -desc => 'name' },
+ }
+);
+
+is($no_prefetch->count, $use_prefetch->count, '$no_prefetch->count == $use_prefetch->count');
+is(
+ scalar ($no_prefetch->all),
+ scalar ($use_prefetch->all),
+ "Amount of returned rows is right"
+);
+
+my $artist_many_cds = $schema->resultset('Artist')->search ( {}, {
+ join => 'cds',
+ group_by => 'me.artistid',
+ having => \ 'count(cds.cdid) > 1',
+})->first;
+
+
+$no_prefetch = $schema->resultset('Artist')->search(
+ { artistid => $artist_many_cds->id },
+ { rows => 1 }
+);
+
+$use_prefetch = $no_prefetch->search ({}, { prefetch => 'cds' });
+
+my $normal_artist = $no_prefetch->single;
+my $prefetch_artist = $use_prefetch->find({ name => $artist_many_cds->name });
+my $prefetch2_artist = $use_prefetch->first;
+
+is(
+ $prefetch_artist->cds->count,
+ $normal_artist->cds->count,
+ "Count of child rel with prefetch + rows => 1 is right (find)"
+);
+is(
+ $prefetch2_artist->cds->count,
+ $normal_artist->cds->count,
+ "Count of child rel with prefetch + rows => 1 is right (first)"
+);
+
+is (
+ scalar ($prefetch_artist->cds->all),
+ scalar ($normal_artist->cds->all),
+ "Amount of child rel rows with prefetch + rows => 1 is right (find)"
+);
+is (
+ scalar ($prefetch2_artist->cds->all),
+ scalar ($normal_artist->cds->all),
+ "Amount of child rel rows with prefetch + rows => 1 is right (first)"
+);
+
+throws_ok (
+ sub { $use_prefetch->single },
+ qr/resultsets prefetching has_many/,
+ 'single() with multiprefetch is illegal',
+);
+
+my $artist = $use_prefetch->search({'cds.title' => $artist_many_cds->cds->first->title })->next;
+is($artist->cds->count, 1, "count on search limiting prefetched has_many");
+
+# try with double limit
+my $artist2 = $use_prefetch->search({'cds.title' => { '!=' => $artist_many_cds->cds->first->title } })->slice (0,0)->next;
+is($artist2->cds->count, 2, "count on search limiting prefetched has_many");
+
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