1 package DBIx::Class::ResultSet;
9 use Carp::Clan qw/^DBIx::Class/;
12 use DBIx::Class::ResultSetColumn;
13 use DBIx::Class::ResultSourceHandle;
14 use base qw/DBIx::Class/;
16 __PACKAGE__->mk_group_accessors('simple' => qw/result_class _source_handle/);
20 DBIx::Class::ResultSet - Responsible for fetching and creating resultset.
24 my $rs = $schema->resultset('User')->search(registered => 1);
25 my @rows = $schema->resultset('CD')->search(year => 2005);
29 The resultset is also known as an iterator. It is responsible for handling
30 queries that may return an arbitrary number of rows, e.g. via L</search>
31 or a C<has_many> relationship.
33 In the examples below, the following table classes are used:
35 package MyApp::Schema::Artist;
36 use base qw/DBIx::Class/;
37 __PACKAGE__->load_components(qw/Core/);
38 __PACKAGE__->table('artist');
39 __PACKAGE__->add_columns(qw/artistid name/);
40 __PACKAGE__->set_primary_key('artistid');
41 __PACKAGE__->has_many(cds => 'MyApp::Schema::CD');
44 package MyApp::Schema::CD;
45 use base qw/DBIx::Class/;
46 __PACKAGE__->load_components(qw/Core/);
47 __PACKAGE__->table('cd');
48 __PACKAGE__->add_columns(qw/cdid artist title year/);
49 __PACKAGE__->set_primary_key('cdid');
50 __PACKAGE__->belongs_to(artist => 'MyApp::Schema::Artist');
59 =item Arguments: $source, \%$attrs
61 =item Return Value: $rs
65 The resultset constructor. Takes a source object (usually a
66 L<DBIx::Class::ResultSourceProxy::Table>) and an attribute hash (see
67 L</ATTRIBUTES> below). Does not perform any queries -- these are
68 executed as needed by the other methods.
70 Generally you won't need to construct a resultset manually. You'll
71 automatically get one from e.g. a L</search> called in scalar context:
73 my $rs = $schema->resultset('CD')->search({ title => '100th Window' });
75 IMPORTANT: If called on an object, proxies to new_result instead so
77 my $cd = $schema->resultset('CD')->new({ title => 'Spoon' });
79 will return a CD object, not a ResultSet.
85 return $class->new_result(@_) if ref $class;
87 my ($source, $attrs) = @_;
88 $source = $source->handle
89 unless $source->isa('DBIx::Class::ResultSourceHandle');
90 $attrs = { %{$attrs||{}} };
93 $attrs->{rows} ||= 10;
94 $attrs->{offset} ||= 0;
95 $attrs->{offset} += ($attrs->{rows} * ($attrs->{page} - 1));
98 $attrs->{alias} ||= 'me';
101 result_source => $source,
102 result_class => $attrs->{result_class} || $source->result_class,
103 cond => $attrs->{where},
118 =item Arguments: $cond, \%attrs?
120 =item Return Value: $resultset (scalar context), @row_objs (list context)
124 my @cds = $cd_rs->search({ year => 2001 }); # "... WHERE year = 2001"
125 my $new_rs = $cd_rs->search({ year => 2005 });
127 my $new_rs = $cd_rs->search([ { year => 2005 }, { year => 2004 } ]);
128 # year = 2005 OR year = 2004
130 If you need to pass in additional attributes but no additional condition,
131 call it as C<search(undef, \%attrs)>.
133 # "SELECT name, artistid FROM $artist_table"
134 my @all_artists = $schema->resultset('Artist')->search(undef, {
135 columns => [qw/name artistid/],
138 For a list of attributes that can be passed to C<search>, see
139 L</ATTRIBUTES>. For more examples of using this function, see
140 L<Searching|DBIx::Class::Manual::Cookbook/Searching>. For a complete
141 documentation for the first argument, see L<SQL::Abstract>.
147 my $rs = $self->search_rs( @_ );
148 return (wantarray ? $rs->all : $rs);
155 =item Arguments: $cond, \%attrs?
157 =item Return Value: $resultset
161 This method does the same exact thing as search() except it will
162 always return a resultset, even in list context.
171 unless (@_) { # no search, effectively just a clone
172 $rows = $self->get_cache;
176 $attrs = pop(@_) if @_ > 1 and ref $_[$#_] eq 'HASH';
177 my $our_attrs = { %{$self->{attrs}} };
178 my $having = delete $our_attrs->{having};
179 my $where = delete $our_attrs->{where};
181 my $new_attrs = { %{$our_attrs}, %{$attrs} };
183 # merge new attrs into inherited
184 foreach my $key (qw/join prefetch/) {
185 next unless exists $attrs->{$key};
186 $new_attrs->{$key} = $self->_merge_attr($our_attrs->{$key}, $attrs->{$key});
191 (@_ == 1 || ref $_[0] eq "HASH")
193 (ref $_[0] eq 'HASH')
195 (keys %{ $_[0] } > 0)
203 ? $self->throw_exception("Odd number of arguments to search")
210 if (defined $where) {
211 $new_attrs->{where} = (
212 defined $new_attrs->{where}
215 ref $_ eq 'ARRAY' ? [ -or => $_ ] : $_
216 } $where, $new_attrs->{where}
223 $new_attrs->{where} = (
224 defined $new_attrs->{where}
227 ref $_ eq 'ARRAY' ? [ -or => $_ ] : $_
228 } $cond, $new_attrs->{where}
234 if (defined $having) {
235 $new_attrs->{having} = (
236 defined $new_attrs->{having}
239 ref $_ eq 'ARRAY' ? [ -or => $_ ] : $_
240 } $having, $new_attrs->{having}
246 my $rs = (ref $self)->new($self->result_source, $new_attrs);
248 $rs->set_cache($rows);
253 =head2 search_literal
257 =item Arguments: $sql_fragment, @bind_values
259 =item Return Value: $resultset (scalar context), @row_objs (list context)
263 my @cds = $cd_rs->search_literal('year = ? AND title = ?', qw/2001 Reload/);
264 my $newrs = $artist_rs->search_literal('name = ?', 'Metallica');
266 Pass a literal chunk of SQL to be added to the conditional part of the
272 my ($self, $cond, @vals) = @_;
273 my $attrs = (ref $vals[$#vals] eq 'HASH' ? { %{ pop(@vals) } } : {});
274 $attrs->{bind} = [ @{$self->{attrs}{bind}||[]}, @vals ];
275 return $self->search(\$cond, $attrs);
282 =item Arguments: @values | \%cols, \%attrs?
284 =item Return Value: $row_object
288 Finds a row based on its primary key or unique constraint. For example, to find
289 a row by its primary key:
291 my $cd = $schema->resultset('CD')->find(5);
293 You can also find a row by a specific unique constraint using the C<key>
294 attribute. For example:
296 my $cd = $schema->resultset('CD')->find('Massive Attack', 'Mezzanine', {
297 key => 'cd_artist_title'
300 Additionally, you can specify the columns explicitly by name:
302 my $cd = $schema->resultset('CD')->find(
304 artist => 'Massive Attack',
305 title => 'Mezzanine',
307 { key => 'cd_artist_title' }
310 If the C<key> is specified as C<primary>, it searches only on the primary key.
312 If no C<key> is specified, it searches on all unique constraints defined on the
313 source, including the primary key.
315 If your table does not have a primary key, you B<must> provide a value for the
316 C<key> attribute matching one of the unique constraints on the source.
318 See also L</find_or_create> and L</update_or_create>. For information on how to
319 declare unique constraints, see
320 L<DBIx::Class::ResultSource/add_unique_constraint>.
326 my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {});
328 # Default to the primary key, but allow a specific key
329 my @cols = exists $attrs->{key}
330 ? $self->result_source->unique_constraint_columns($attrs->{key})
331 : $self->result_source->primary_columns;
332 $self->throw_exception(
333 "Can't find unless a primary key is defined or unique constraint is specified"
336 # Parse out a hashref from input
338 if (ref $_[0] eq 'HASH') {
339 $input_query = { %{$_[0]} };
341 elsif (@_ == @cols) {
343 @{$input_query}{@cols} = @_;
346 # Compatibility: Allow e.g. find(id => $value)
347 carp "Find by key => value deprecated; please use a hashref instead";
351 my (%related, $info);
353 foreach my $key (keys %$input_query) {
354 if (ref($input_query->{$key})
355 && ($info = $self->result_source->relationship_info($key))) {
356 my $rel_q = $self->result_source->resolve_condition(
357 $info->{cond}, delete $input_query->{$key}, $key
359 die "Can't handle OR join condition in find" if ref($rel_q) eq 'ARRAY';
360 @related{keys %$rel_q} = values %$rel_q;
363 if (my @keys = keys %related) {
364 @{$input_query}{@keys} = values %related;
367 my @unique_queries = $self->_unique_queries($input_query, $attrs);
369 # Build the final query: Default to the disjunction of the unique queries,
370 # but allow the input query in case the ResultSet defines the query or the
371 # user is abusing find
372 my $alias = exists $attrs->{alias} ? $attrs->{alias} : $self->{attrs}{alias};
373 my $query = @unique_queries
374 ? [ map { $self->_add_alias($_, $alias) } @unique_queries ]
375 : $self->_add_alias($input_query, $alias);
379 my $rs = $self->search($query, $attrs);
380 return keys %{$rs->_resolved_attrs->{collapse}} ? $rs->next : $rs->single;
383 return keys %{$self->_resolved_attrs->{collapse}}
384 ? $self->search($query)->next
385 : $self->single($query);
391 # Add the specified alias to the specified query hash. A copy is made so the
392 # original query is not modified.
395 my ($self, $query, $alias) = @_;
397 my %aliased = %$query;
398 foreach my $col (grep { ! m/\./ } keys %aliased) {
399 $aliased{"$alias.$col"} = delete $aliased{$col};
407 # Build a list of queries which satisfy unique constraints.
409 sub _unique_queries {
410 my ($self, $query, $attrs) = @_;
412 my @constraint_names = exists $attrs->{key}
414 : $self->result_source->unique_constraint_names;
416 my $where = $self->_collapse_cond($self->{attrs}{where} || {});
417 my $num_where = scalar keys %$where;
420 foreach my $name (@constraint_names) {
421 my @unique_cols = $self->result_source->unique_constraint_columns($name);
422 my $unique_query = $self->_build_unique_query($query, \@unique_cols);
424 my $num_cols = scalar @unique_cols;
425 my $num_query = scalar keys %$unique_query;
427 my $total = $num_query + $num_where;
428 if ($num_query && ($num_query == $num_cols || $total == $num_cols)) {
429 # The query is either unique on its own or is unique in combination with
430 # the existing where clause
431 push @unique_queries, $unique_query;
435 return @unique_queries;
438 # _build_unique_query
440 # Constrain the specified query hash based on the specified column names.
442 sub _build_unique_query {
443 my ($self, $query, $unique_cols) = @_;
446 map { $_ => $query->{$_} }
447 grep { exists $query->{$_} }
452 =head2 search_related
456 =item Arguments: $rel, $cond, \%attrs?
458 =item Return Value: $new_resultset
462 $new_rs = $cd_rs->search_related('artist', {
466 Searches the specified relationship, optionally specifying a condition and
467 attributes for matching records. See L</ATTRIBUTES> for more information.
472 return shift->related_resultset(shift)->search(@_);
479 =item Arguments: none
481 =item Return Value: $cursor
485 Returns a storage-driven cursor to the given resultset. See
486 L<DBIx::Class::Cursor> for more information.
493 my $attrs = { %{$self->_resolved_attrs} };
494 return $self->{cursor}
495 ||= $self->result_source->storage->select($attrs->{from}, $attrs->{select},
496 $attrs->{where},$attrs);
503 =item Arguments: $cond?
505 =item Return Value: $row_object?
509 my $cd = $schema->resultset('CD')->single({ year => 2001 });
511 Inflates the first result without creating a cursor if the resultset has
512 any records in it; if not returns nothing. Used by L</find> as an optimisation.
514 Can optionally take an additional condition *only* - this is a fast-code-path
515 method; if you need to add extra joins or similar call ->search and then
516 ->single without a condition on the $rs returned from that.
521 my ($self, $where) = @_;
522 my $attrs = { %{$self->_resolved_attrs} };
524 if (defined $attrs->{where}) {
527 [ map { ref $_ eq 'ARRAY' ? [ -or => $_ ] : $_ }
528 $where, delete $attrs->{where} ]
531 $attrs->{where} = $where;
535 # XXX: Disabled since it doesn't infer uniqueness in all cases
536 # unless ($self->_is_unique_query($attrs->{where})) {
537 # carp "Query not guaranteed to return a single row"
538 # . "; please declare your unique constraints or use search instead";
541 my @data = $self->result_source->storage->select_single(
542 $attrs->{from}, $attrs->{select},
543 $attrs->{where}, $attrs
546 return (@data ? ($self->_construct_object(@data))[0] : ());
551 # Try to determine if the specified query is guaranteed to be unique, based on
552 # the declared unique constraints.
554 sub _is_unique_query {
555 my ($self, $query) = @_;
557 my $collapsed = $self->_collapse_query($query);
558 my $alias = $self->{attrs}{alias};
560 foreach my $name ($self->result_source->unique_constraint_names) {
561 my @unique_cols = map {
563 } $self->result_source->unique_constraint_columns($name);
565 # Count the values for each unique column
566 my %seen = map { $_ => 0 } @unique_cols;
568 foreach my $key (keys %$collapsed) {
569 my $aliased = $key =~ /\./ ? $key : "$alias.$key";
570 next unless exists $seen{$aliased}; # Additional constraints are okay
571 $seen{$aliased} = scalar keys %{ $collapsed->{$key} };
574 # If we get 0 or more than 1 value for a column, it's not necessarily unique
575 return 1 unless grep { $_ != 1 } values %seen;
583 # Recursively collapse the query, accumulating values for each column.
585 sub _collapse_query {
586 my ($self, $query, $collapsed) = @_;
590 if (ref $query eq 'ARRAY') {
591 foreach my $subquery (@$query) {
592 next unless ref $subquery; # -or
593 # warn "ARRAY: " . Dumper $subquery;
594 $collapsed = $self->_collapse_query($subquery, $collapsed);
597 elsif (ref $query eq 'HASH') {
598 if (keys %$query and (keys %$query)[0] eq '-and') {
599 foreach my $subquery (@{$query->{-and}}) {
600 # warn "HASH: " . Dumper $subquery;
601 $collapsed = $self->_collapse_query($subquery, $collapsed);
605 # warn "LEAF: " . Dumper $query;
606 foreach my $col (keys %$query) {
607 my $value = $query->{$col};
608 $collapsed->{$col}{$value}++;
620 =item Arguments: $cond?
622 =item Return Value: $resultsetcolumn
626 my $max_length = $rs->get_column('length')->max;
628 Returns a L<DBIx::Class::ResultSetColumn> instance for a column of the ResultSet.
633 my ($self, $column) = @_;
634 my $new = DBIx::Class::ResultSetColumn->new($self, $column);
642 =item Arguments: $cond, \%attrs?
644 =item Return Value: $resultset (scalar context), @row_objs (list context)
648 # WHERE title LIKE '%blue%'
649 $cd_rs = $rs->search_like({ title => '%blue%'});
651 Performs a search, but uses C<LIKE> instead of C<=> as the condition. Note
652 that this is simply a convenience method. You most likely want to use
653 L</search> with specific operators.
655 For more information, see L<DBIx::Class::Manual::Cookbook>.
661 my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {});
662 my $query = ref $_[0] eq 'HASH' ? { %{shift()} }: {@_};
663 $query->{$_} = { 'like' => $query->{$_} } for keys %$query;
664 return $class->search($query, { %$attrs });
671 =item Arguments: $first, $last
673 =item Return Value: $resultset (scalar context), @row_objs (list context)
677 Returns a resultset or object list representing a subset of elements from the
678 resultset slice is called on. Indexes are from 0, i.e., to get the first
681 my ($one, $two, $three) = $rs->slice(0, 2);
686 my ($self, $min, $max) = @_;
687 my $attrs = {}; # = { %{ $self->{attrs} || {} } };
688 $attrs->{offset} = $self->{attrs}{offset} || 0;
689 $attrs->{offset} += $min;
690 $attrs->{rows} = ($max ? ($max - $min + 1) : 1);
691 return $self->search(undef(), $attrs);
692 #my $slice = (ref $self)->new($self->result_source, $attrs);
693 #return (wantarray ? $slice->all : $slice);
700 =item Arguments: none
702 =item Return Value: $result?
706 Returns the next element in the resultset (C<undef> is there is none).
708 Can be used to efficiently iterate over records in the resultset:
710 my $rs = $schema->resultset('CD')->search;
711 while (my $cd = $rs->next) {
715 Note that you need to store the resultset object, and call C<next> on it.
716 Calling C<< resultset('Table')->next >> repeatedly will always return the
717 first record from the resultset.
723 if (my $cache = $self->get_cache) {
724 $self->{all_cache_position} ||= 0;
725 return $cache->[$self->{all_cache_position}++];
727 if ($self->{attrs}{cache}) {
728 $self->{all_cache_position} = 1;
729 return ($self->all)[0];
731 if ($self->{stashed_objects}) {
732 my $obj = shift(@{$self->{stashed_objects}});
733 delete $self->{stashed_objects} unless @{$self->{stashed_objects}};
737 exists $self->{stashed_row}
738 ? @{delete $self->{stashed_row}}
739 : $self->cursor->next
741 return unless (@row);
742 my ($row, @more) = $self->_construct_object(@row);
743 $self->{stashed_objects} = \@more if @more;
747 sub _construct_object {
748 my ($self, @row) = @_;
749 my $info = $self->_collapse_result($self->{_attrs}{as}, \@row);
750 my @new = $self->result_class->inflate_result($self->result_source, @$info);
751 @new = $self->{_attrs}{record_filter}->(@new)
752 if exists $self->{_attrs}{record_filter};
756 sub _collapse_result {
757 my ($self, $as_proto, $row) = @_;
761 # 'foo' => [ undef, 'foo' ]
762 # 'foo.bar' => [ 'foo', 'bar' ]
763 # 'foo.bar.baz' => [ 'foo.bar', 'baz' ]
765 my @construct_as = map { [ (/^(?:(.*)\.)?([^.]+)$/) ] } @$as_proto;
767 my %collapse = %{$self->{_attrs}{collapse}||{}};
771 # if we're doing collapsing (has_many prefetch) we need to grab records
772 # until the PK changes, so fill @pri_index. if not, we leave it empty so
773 # we know we don't have to bother.
775 # the reason for not using the collapse stuff directly is because if you
776 # had for e.g. two artists in a row with no cds, the collapse info for
777 # both would be NULL (undef) so you'd lose the second artist
779 # store just the index so we can check the array positions from the row
780 # without having to contruct the full hash
782 if (keys %collapse) {
783 my %pri = map { ($_ => 1) } $self->result_source->primary_columns;
784 foreach my $i (0 .. $#construct_as) {
785 next if defined($construct_as[$i][0]); # only self table
786 if (delete $pri{$construct_as[$i][1]}) {
787 push(@pri_index, $i);
789 last unless keys %pri; # short circuit (Johnny Five Is Alive!)
793 # no need to do an if, it'll be empty if @pri_index is empty anyway
795 my %pri_vals = map { ($_ => $copy[$_]) } @pri_index;
799 do { # no need to check anything at the front, we always want the first row
803 foreach my $this_as (@construct_as) {
804 $const{$this_as->[0]||''}{$this_as->[1]} = shift(@copy);
807 push(@const_rows, \%const);
809 } until ( # no pri_index => no collapse => drop straight out
812 do { # get another row, stash it, drop out if different PK
814 @copy = $self->cursor->next;
815 $self->{stashed_row} = \@copy;
817 # last thing in do block, counts as true if anything doesn't match
819 # check xor defined first for NULL vs. NOT NULL then if one is
820 # defined the other must be so check string equality
823 (defined $pri_vals{$_} ^ defined $copy[$_])
824 || (defined $pri_vals{$_} && ($pri_vals{$_} ne $copy[$_]))
829 # THIS BIT STILL NEEDS TO DO THE COLLAPSE
831 my $alias = $self->{attrs}{alias};
840 foreach my $const (@const_rows) {
841 scalar @const_keys or do {
842 @const_keys = sort { length($a) <=> length($b) } keys %$const;
844 foreach my $key (@const_keys) {
847 my @parts = split(/\./, $key);
849 my $data = $const->{$key};
850 foreach my $p (@parts) {
851 $target = $target->[1]->{$p} ||= [];
853 if ($cur eq ".${key}" && (my @ckey = @{$collapse{$cur}||[]})) {
854 # collapsing at this point and on final part
855 my $pos = $collapse_pos{$cur};
856 CK: foreach my $ck (@ckey) {
857 if (!defined $pos->{$ck} || $pos->{$ck} ne $data->{$ck}) {
858 $collapse_pos{$cur} = $data;
859 delete @collapse_pos{ # clear all positioning for sub-entries
860 grep { m/^\Q${cur}.\E/ } keys %collapse_pos
867 if (exists $collapse{$cur}) {
868 $target = $target->[-1];
871 $target->[0] = $data;
873 $info->[0] = $const->{$key};
885 =item Arguments: $result_source?
887 =item Return Value: $result_source
891 An accessor for the primary ResultSource object from which this ResultSet
898 =item Arguments: $result_class?
900 =item Return Value: $result_class
904 An accessor for the class to use when creating row objects. Defaults to
905 C<< result_source->result_class >> - which in most cases is the name of the
906 L<"table"|DBIx::Class::Manual::Glossary/"ResultSource"> class.
915 =item Arguments: $cond, \%attrs??
917 =item Return Value: $count
921 Performs an SQL C<COUNT> with the same query as the resultset was built
922 with to find the number of elements. If passed arguments, does a search
923 on the resultset and counts the results of that.
925 Note: When using C<count> with C<group_by>, L<DBIX::Class> emulates C<GROUP BY>
926 using C<COUNT( DISTINCT( columns ) )>. Some databases (notably SQLite) do
927 not support C<DISTINCT> with multiple columns. If you are using such a
928 database, you should only use columns from the main table in your C<group_by>
935 return $self->search(@_)->count if @_ and defined $_[0];
936 return scalar @{ $self->get_cache } if $self->get_cache;
937 my $count = $self->_count;
938 return 0 unless $count;
940 $count -= $self->{attrs}{offset} if $self->{attrs}{offset};
941 $count = $self->{attrs}{rows} if
942 $self->{attrs}{rows} and $self->{attrs}{rows} < $count;
946 sub _count { # Separated out so pager can get the full count
948 my $select = { count => '*' };
950 my $attrs = { %{$self->_resolved_attrs} };
951 if (my $group_by = delete $attrs->{group_by}) {
952 delete $attrs->{having};
953 my @distinct = (ref $group_by ? @$group_by : ($group_by));
954 # todo: try CONCAT for multi-column pk
955 my @pk = $self->result_source->primary_columns;
957 my $alias = $attrs->{alias};
958 foreach my $column (@distinct) {
959 if ($column =~ qr/^(?:\Q${alias}.\E)?$pk[0]$/) {
960 @distinct = ($column);
966 $select = { count => { distinct => \@distinct } };
969 $attrs->{select} = $select;
970 $attrs->{as} = [qw/count/];
972 # offset, order by and page are not needed to count. record_filter is cdbi
973 delete $attrs->{$_} for qw/rows offset order_by page pager record_filter/;
975 my $tmp_rs = (ref $self)->new($self->_source_handle, $attrs);
976 my ($count) = $tmp_rs->cursor->next;
984 =item Arguments: $sql_fragment, @bind_values
986 =item Return Value: $count
990 Counts the results in a literal query. Equivalent to calling L</search_literal>
991 with the passed arguments, then L</count>.
995 sub count_literal { shift->search_literal(@_)->count; }
1001 =item Arguments: none
1003 =item Return Value: @objects
1007 Returns all elements in the resultset. Called implicitly if the resultset
1008 is returned in list context.
1014 return @{ $self->get_cache } if $self->get_cache;
1018 # TODO: don't call resolve here
1019 if (keys %{$self->_resolved_attrs->{collapse}}) {
1020 # if ($self->{attrs}{prefetch}) {
1021 # Using $self->cursor->all is really just an optimisation.
1022 # If we're collapsing has_many prefetches it probably makes
1023 # very little difference, and this is cleaner than hacking
1024 # _construct_object to survive the approach
1025 my @row = $self->cursor->next;
1027 push(@obj, $self->_construct_object(@row));
1028 @row = (exists $self->{stashed_row}
1029 ? @{delete $self->{stashed_row}}
1030 : $self->cursor->next);
1033 @obj = map { $self->_construct_object(@$_) } $self->cursor->all;
1036 $self->set_cache(\@obj) if $self->{attrs}{cache};
1044 =item Arguments: none
1046 =item Return Value: $self
1050 Resets the resultset's cursor, so you can iterate through the elements again.
1056 delete $self->{_attrs} if exists $self->{_attrs};
1057 $self->{all_cache_position} = 0;
1058 $self->cursor->reset;
1066 =item Arguments: none
1068 =item Return Value: $object?
1072 Resets the resultset and returns an object for the first result (if the
1073 resultset returns anything).
1078 return $_[0]->reset->next;
1081 # _cond_for_update_delete
1083 # update/delete require the condition to be modified to handle
1084 # the differing SQL syntax available. This transforms the $self->{cond}
1085 # appropriately, returning the new condition.
1087 sub _cond_for_update_delete {
1088 my ($self, $full_cond) = @_;
1091 $full_cond ||= $self->{cond};
1092 # No-op. No condition, we're updating/deleting everything
1093 return $cond unless ref $full_cond;
1095 if (ref $full_cond eq 'ARRAY') {
1099 foreach my $key (keys %{$_}) {
1101 $hash{$1} = $_->{$key};
1107 elsif (ref $full_cond eq 'HASH') {
1108 if ((keys %{$full_cond})[0] eq '-and') {
1111 my @cond = @{$full_cond->{-and}};
1112 for (my $i = 0; $i < @cond; $i++) {
1113 my $entry = $cond[$i];
1116 if (ref $entry eq 'HASH') {
1117 $hash = $self->_cond_for_update_delete($entry);
1120 $entry =~ /([^.]+)$/;
1121 $hash->{$1} = $cond[++$i];
1124 push @{$cond->{-and}}, $hash;
1128 foreach my $key (keys %{$full_cond}) {
1130 $cond->{$1} = $full_cond->{$key};
1135 $self->throw_exception(
1136 "Can't update/delete on resultset with condition unless hash or array"
1148 =item Arguments: \%values
1150 =item Return Value: $storage_rv
1154 Sets the specified columns in the resultset to the supplied values in a
1155 single query. Return value will be true if the update succeeded or false
1156 if no records were updated; exact type of success value is storage-dependent.
1161 my ($self, $values) = @_;
1162 $self->throw_exception("Values for update must be a hash")
1163 unless ref $values eq 'HASH';
1165 my $cond = $self->_cond_for_update_delete;
1167 return $self->result_source->storage->update(
1168 $self->result_source, $values, $cond
1176 =item Arguments: \%values
1178 =item Return Value: 1
1182 Fetches all objects and updates them one at a time. Note that C<update_all>
1183 will run DBIC cascade triggers, while L</update> will not.
1188 my ($self, $values) = @_;
1189 $self->throw_exception("Values for update must be a hash")
1190 unless ref $values eq 'HASH';
1191 foreach my $obj ($self->all) {
1192 $obj->set_columns($values)->update;
1201 =item Arguments: none
1203 =item Return Value: 1
1207 Deletes the contents of the resultset from its result source. Note that this
1208 will not run DBIC cascade triggers. See L</delete_all> if you need triggers
1209 to run. See also L<DBIx::Class::Row/delete>.
1216 my $cond = $self->_cond_for_update_delete;
1218 $self->result_source->storage->delete($self->result_source, $cond);
1226 =item Arguments: none
1228 =item Return Value: 1
1232 Fetches all objects and deletes them one at a time. Note that C<delete_all>
1233 will run DBIC cascade triggers, while L</delete> will not.
1239 $_->delete for $self->all;
1247 =item Arguments: none
1249 =item Return Value: $pager
1253 Return Value a L<Data::Page> object for the current resultset. Only makes
1254 sense for queries with a C<page> attribute.
1260 my $attrs = $self->{attrs};
1261 $self->throw_exception("Can't create pager for non-paged rs")
1262 unless $self->{attrs}{page};
1263 $attrs->{rows} ||= 10;
1264 return $self->{pager} ||= Data::Page->new(
1265 $self->_count, $attrs->{rows}, $self->{attrs}{page});
1272 =item Arguments: $page_number
1274 =item Return Value: $rs
1278 Returns a resultset for the $page_number page of the resultset on which page
1279 is called, where each page contains a number of rows equal to the 'rows'
1280 attribute set on the resultset (10 by default).
1285 my ($self, $page) = @_;
1286 return (ref $self)->new($self->_source_handle, { %{$self->{attrs}}, page => $page });
1293 =item Arguments: \%vals
1295 =item Return Value: $object
1299 Creates an object in the resultset's result class and returns it.
1304 my ($self, $values) = @_;
1305 $self->throw_exception( "new_result needs a hash" )
1306 unless (ref $values eq 'HASH');
1307 $self->throw_exception(
1308 "Can't abstract implicit construct, condition not a hash"
1309 ) if ($self->{cond} && !(ref $self->{cond} eq 'HASH'));
1311 my $alias = $self->{attrs}{alias};
1312 my $collapsed_cond = $self->{cond} ? $self->_collapse_cond($self->{cond}) : {};
1314 %{ $self->_remove_alias($values, $alias) },
1315 %{ $self->_remove_alias($collapsed_cond, $alias) },
1316 -source_handle => $self->_source_handle
1319 return $self->result_class->new(\%new);
1324 # Recursively collapse the condition.
1326 sub _collapse_cond {
1327 my ($self, $cond, $collapsed) = @_;
1331 if (ref $cond eq 'ARRAY') {
1332 foreach my $subcond (@$cond) {
1333 next unless ref $subcond; # -or
1334 # warn "ARRAY: " . Dumper $subcond;
1335 $collapsed = $self->_collapse_cond($subcond, $collapsed);
1338 elsif (ref $cond eq 'HASH') {
1339 if (keys %$cond and (keys %$cond)[0] eq '-and') {
1340 foreach my $subcond (@{$cond->{-and}}) {
1341 # warn "HASH: " . Dumper $subcond;
1342 $collapsed = $self->_collapse_cond($subcond, $collapsed);
1346 # warn "LEAF: " . Dumper $cond;
1347 foreach my $col (keys %$cond) {
1348 my $value = $cond->{$col};
1349 $collapsed->{$col} = $value;
1359 # Remove the specified alias from the specified query hash. A copy is made so
1360 # the original query is not modified.
1363 my ($self, $query, $alias) = @_;
1365 my %orig = %{ $query || {} };
1368 foreach my $key (keys %orig) {
1370 $unaliased{$key} = $orig{$key};
1373 $unaliased{$1} = $orig{$key}
1374 if $key =~ m/^(?:\Q$alias\E\.)?([^.]+)$/;
1384 =item Arguments: \%vals, \%attrs?
1386 =item Return Value: $object
1390 Find an existing record from this resultset. If none exists, instantiate a new
1391 result object and return it. The object will not be saved into your storage
1392 until you call L<DBIx::Class::Row/insert> on it.
1394 If you want objects to be saved immediately, use L</find_or_create> instead.
1400 my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {});
1401 my $hash = ref $_[0] eq 'HASH' ? shift : {@_};
1402 my $exists = $self->find($hash, $attrs);
1403 return defined $exists ? $exists : $self->new_result($hash);
1410 =item Arguments: \%vals
1412 =item Return Value: $object
1416 Inserts a record into the resultset and returns the object representing it.
1418 Effectively a shortcut for C<< ->new_result(\%vals)->insert >>.
1423 my ($self, $attrs) = @_;
1424 $self->throw_exception( "create needs a hashref" )
1425 unless ref $attrs eq 'HASH';
1426 return $self->new_result($attrs)->insert;
1429 =head2 find_or_create
1433 =item Arguments: \%vals, \%attrs?
1435 =item Return Value: $object
1439 $class->find_or_create({ key => $val, ... });
1441 Tries to find a record based on its primary key or unique constraint; if none
1442 is found, creates one and returns that instead.
1444 my $cd = $schema->resultset('CD')->find_or_create({
1446 artist => 'Massive Attack',
1447 title => 'Mezzanine',
1451 Also takes an optional C<key> attribute, to search by a specific key or unique
1452 constraint. For example:
1454 my $cd = $schema->resultset('CD')->find_or_create(
1456 artist => 'Massive Attack',
1457 title => 'Mezzanine',
1459 { key => 'cd_artist_title' }
1462 See also L</find> and L</update_or_create>. For information on how to declare
1463 unique constraints, see L<DBIx::Class::ResultSource/add_unique_constraint>.
1467 sub find_or_create {
1469 my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {});
1470 my $hash = ref $_[0] eq 'HASH' ? shift : {@_};
1471 my $exists = $self->find($hash, $attrs);
1472 return defined $exists ? $exists : $self->create($hash);
1475 =head2 update_or_create
1479 =item Arguments: \%col_values, { key => $unique_constraint }?
1481 =item Return Value: $object
1485 $class->update_or_create({ col => $val, ... });
1487 First, searches for an existing row matching one of the unique constraints
1488 (including the primary key) on the source of this resultset. If a row is
1489 found, updates it with the other given column values. Otherwise, creates a new
1492 Takes an optional C<key> attribute to search on a specific unique constraint.
1495 # In your application
1496 my $cd = $schema->resultset('CD')->update_or_create(
1498 artist => 'Massive Attack',
1499 title => 'Mezzanine',
1502 { key => 'cd_artist_title' }
1505 If no C<key> is specified, it searches on all unique constraints defined on the
1506 source, including the primary key.
1508 If the C<key> is specified as C<primary>, it searches only on the primary key.
1510 See also L</find> and L</find_or_create>. For information on how to declare
1511 unique constraints, see L<DBIx::Class::ResultSource/add_unique_constraint>.
1515 sub update_or_create {
1517 my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {});
1518 my $cond = ref $_[0] eq 'HASH' ? shift : {@_};
1520 my $row = $self->find($cond, $attrs);
1522 $row->update($cond);
1526 return $self->create($cond);
1533 =item Arguments: none
1535 =item Return Value: \@cache_objects?
1539 Gets the contents of the cache for the resultset, if the cache is set.
1551 =item Arguments: \@cache_objects
1553 =item Return Value: \@cache_objects
1557 Sets the contents of the cache for the resultset. Expects an arrayref
1558 of objects of the same class as those produced by the resultset. Note that
1559 if the cache is set the resultset will return the cached objects rather
1560 than re-querying the database even if the cache attr is not set.
1565 my ( $self, $data ) = @_;
1566 $self->throw_exception("set_cache requires an arrayref")
1567 if defined($data) && (ref $data ne 'ARRAY');
1568 $self->{all_cache} = $data;
1575 =item Arguments: none
1577 =item Return Value: []
1581 Clears the cache for the resultset.
1586 shift->set_cache(undef);
1589 =head2 related_resultset
1593 =item Arguments: $relationship_name
1595 =item Return Value: $resultset
1599 Returns a related resultset for the supplied relationship name.
1601 $artist_rs = $schema->resultset('CD')->related_resultset('Artist');
1605 sub related_resultset {
1606 my ($self, $rel) = @_;
1608 $self->{related_resultsets} ||= {};
1609 return $self->{related_resultsets}{$rel} ||= do {
1610 my $rel_obj = $self->result_source->relationship_info($rel);
1612 $self->throw_exception(
1613 "search_related: result source '" . $self->_source_handle->source_moniker .
1614 "' has no such relationship $rel")
1617 my ($from,$seen) = $self->_resolve_from($rel);
1619 my $join_count = $seen->{$rel};
1620 my $alias = ($join_count > 1 ? join('_', $rel, $join_count) : $rel);
1622 $self->_source_handle->schema->resultset($rel_obj->{class})->search_rs(
1624 %{$self->{attrs}||{}},
1630 where => $self->{cond},
1638 my ($self, $extra_join) = @_;
1639 my $source = $self->result_source;
1640 my $attrs = $self->{attrs};
1642 my $from = $attrs->{from}
1643 || [ { $attrs->{alias} => $source->from } ];
1645 my $seen = { %{$attrs->{seen_join}||{}} };
1647 my $join = ($attrs->{join}
1648 ? [ $attrs->{join}, $extra_join ]
1652 ($join ? $source->resolve_join($join, $attrs->{alias}, $seen) : ()),
1655 return ($from,$seen);
1658 sub _resolved_attrs {
1660 return $self->{_attrs} if $self->{_attrs};
1662 my $attrs = { %{$self->{attrs}||{}} };
1663 my $source = $self->result_source;
1664 my $alias = $attrs->{alias};
1666 $attrs->{columns} ||= delete $attrs->{cols} if exists $attrs->{cols};
1667 if ($attrs->{columns}) {
1668 delete $attrs->{as};
1669 } elsif (!$attrs->{select}) {
1670 $attrs->{columns} = [ $source->columns ];
1675 ? (ref $attrs->{select} eq 'ARRAY'
1676 ? [ @{$attrs->{select}} ]
1677 : [ $attrs->{select} ])
1678 : [ map { m/\./ ? $_ : "${alias}.$_" } @{delete $attrs->{columns}} ]
1682 ? (ref $attrs->{as} eq 'ARRAY'
1683 ? [ @{$attrs->{as}} ]
1685 : [ map { m/^\Q${alias}.\E(.+)$/ ? $1 : $_ } @{$attrs->{select}} ]
1689 if ($adds = delete $attrs->{include_columns}) {
1690 $adds = [$adds] unless ref $adds eq 'ARRAY';
1691 push(@{$attrs->{select}}, @$adds);
1692 push(@{$attrs->{as}}, map { m/([^.]+)$/; $1 } @$adds);
1694 if ($adds = delete $attrs->{'+select'}) {
1695 $adds = [$adds] unless ref $adds eq 'ARRAY';
1696 push(@{$attrs->{select}},
1697 map { /\./ || ref $_ ? $_ : "${alias}.$_" } @$adds);
1699 if (my $adds = delete $attrs->{'+as'}) {
1700 $adds = [$adds] unless ref $adds eq 'ARRAY';
1701 push(@{$attrs->{as}}, @$adds);
1704 $attrs->{from} ||= [ { 'me' => $source->from } ];
1706 if (exists $attrs->{join} || exists $attrs->{prefetch}) {
1707 my $join = delete $attrs->{join} || {};
1709 if (defined $attrs->{prefetch}) {
1710 $join = $self->_merge_attr(
1711 $join, $attrs->{prefetch}
1715 $attrs->{from} = # have to copy here to avoid corrupting the original
1718 $source->resolve_join($join, $alias, { %{$attrs->{seen_join}||{}} })
1722 $attrs->{group_by} ||= $attrs->{select} if delete $attrs->{distinct};
1723 if ($attrs->{order_by}) {
1724 $attrs->{order_by} = (ref($attrs->{order_by}) eq 'ARRAY'
1725 ? [ @{$attrs->{order_by}} ]
1726 : [ $attrs->{order_by} ]);
1728 $attrs->{order_by} = [];
1731 my $collapse = $attrs->{collapse} || {};
1732 if (my $prefetch = delete $attrs->{prefetch}) {
1733 $prefetch = $self->_merge_attr({}, $prefetch);
1735 my $seen = $attrs->{seen_join} || {};
1736 foreach my $p (ref $prefetch eq 'ARRAY' ? @$prefetch : ($prefetch)) {
1737 # bring joins back to level of current class
1738 my @prefetch = $source->resolve_prefetch(
1739 $p, $alias, $seen, \@pre_order, $collapse
1741 push(@{$attrs->{select}}, map { $_->[0] } @prefetch);
1742 push(@{$attrs->{as}}, map { $_->[1] } @prefetch);
1744 push(@{$attrs->{order_by}}, @pre_order);
1746 $attrs->{collapse} = $collapse;
1748 return $self->{_attrs} = $attrs;
1752 my ($self, $a, $b) = @_;
1753 return $b unless defined($a);
1754 return $a unless defined($b);
1756 if (ref $b eq 'HASH' && ref $a eq 'HASH') {
1757 foreach my $key (keys %{$b}) {
1758 if (exists $a->{$key}) {
1759 $a->{$key} = $self->_merge_attr($a->{$key}, $b->{$key});
1761 $a->{$key} = $b->{$key};
1766 $a = [$a] unless ref $a eq 'ARRAY';
1767 $b = [$b] unless ref $b eq 'ARRAY';
1771 foreach my $x ($a, $b) {
1772 foreach my $element (@{$x}) {
1773 if (ref $element eq 'HASH') {
1774 $hash = $self->_merge_attr($hash, $element);
1775 } elsif (ref $element eq 'ARRAY') {
1776 push(@array, @{$element});
1778 push(@array, $element) unless $b == $x
1779 && grep { $_ eq $element } @array;
1784 @array = grep { !exists $hash->{$_} } @array;
1786 return keys %{$hash}
1799 $self->_source_handle($_[0]->handle);
1801 $self->_source_handle->resolve;
1805 =head2 throw_exception
1807 See L<DBIx::Class::Schema/throw_exception> for details.
1811 sub throw_exception {
1813 $self->_source_handle->schema->throw_exception(@_);
1816 # XXX: FIXME: Attributes docs need clearing up
1820 The resultset takes various attributes that modify its behavior. Here's an
1827 =item Value: ($order_by | \@order_by)
1831 Which column(s) to order the results by. This is currently passed
1832 through directly to SQL, so you can give e.g. C<year DESC> for a
1833 descending order on the column `year'.
1835 Please note that if you have C<quote_char> enabled (see
1836 L<DBIx::Class::Storage::DBI/connect_info>) you will need to do C<\'year DESC' > to
1837 specify an order. (The scalar ref causes it to be passed as raw sql to the DB,
1838 so you will need to manually quote things as appropriate.)
1844 =item Value: \@columns
1848 Shortcut to request a particular set of columns to be retrieved. Adds
1849 C<me.> onto the start of any column without a C<.> in it and sets C<select>
1850 from that, then auto-populates C<as> from C<select> as normal. (You may also
1851 use the C<cols> attribute, as in earlier versions of DBIC.)
1853 =head2 include_columns
1857 =item Value: \@columns
1861 Shortcut to include additional columns in the returned results - for example
1863 $schema->resultset('CD')->search(undef, {
1864 include_columns => ['artist.name'],
1868 would return all CDs and include a 'name' column to the information
1869 passed to object inflation. Note that the 'artist' is the name of the
1870 column (or relationship) accessor, and 'name' is the name of the column
1871 accessor in the related table.
1877 =item Value: \@select_columns
1881 Indicates which columns should be selected from the storage. You can use
1882 column names, or in the case of RDBMS back ends, function or stored procedure
1885 $rs = $schema->resultset('Employee')->search(undef, {
1888 { count => 'employeeid' },
1893 When you use function/stored procedure names and do not supply an C<as>
1894 attribute, the column names returned are storage-dependent. E.g. MySQL would
1895 return a column named C<count(employeeid)> in the above example.
1901 Indicates additional columns to be selected from storage. Works the same as
1902 L<select> but adds columns to the selection.
1910 Indicates additional column names for those added via L<+select>.
1918 =item Value: \@inflation_names
1922 Indicates column names for object inflation. That is, c< as >
1923 indicates the name that the column can be accessed as via the
1924 C<get_column> method (or via the object accessor, B<if one already
1925 exists>). It has nothing to do with the SQL code C< SELECT foo AS bar
1928 The C< as > attribute is used in conjunction with C<select>,
1929 usually when C<select> contains one or more function or stored
1932 $rs = $schema->resultset('Employee')->search(undef, {
1935 { count => 'employeeid' }
1937 as => ['name', 'employee_count'],
1940 my $employee = $rs->first(); # get the first Employee
1942 If the object against which the search is performed already has an accessor
1943 matching a column name specified in C<as>, the value can be retrieved using
1944 the accessor as normal:
1946 my $name = $employee->name();
1948 If on the other hand an accessor does not exist in the object, you need to
1949 use C<get_column> instead:
1951 my $employee_count = $employee->get_column('employee_count');
1953 You can create your own accessors if required - see
1954 L<DBIx::Class::Manual::Cookbook> for details.
1956 Please note: This will NOT insert an C<AS employee_count> into the SQL
1957 statement produced, it is used for internal access only. Thus
1958 attempting to use the accessor in an C<order_by> clause or similar
1959 will fail miserably.
1961 To get around this limitation, you can supply literal SQL to your
1962 C<select> attibute that contains the C<AS alias> text, eg:
1964 select => [\'myfield AS alias']
1970 =item Value: ($rel_name | \@rel_names | \%rel_names)
1974 Contains a list of relationships that should be joined for this query. For
1977 # Get CDs by Nine Inch Nails
1978 my $rs = $schema->resultset('CD')->search(
1979 { 'artist.name' => 'Nine Inch Nails' },
1980 { join => 'artist' }
1983 Can also contain a hash reference to refer to the other relation's relations.
1986 package MyApp::Schema::Track;
1987 use base qw/DBIx::Class/;
1988 __PACKAGE__->table('track');
1989 __PACKAGE__->add_columns(qw/trackid cd position title/);
1990 __PACKAGE__->set_primary_key('trackid');
1991 __PACKAGE__->belongs_to(cd => 'MyApp::Schema::CD');
1994 # In your application
1995 my $rs = $schema->resultset('Artist')->search(
1996 { 'track.title' => 'Teardrop' },
1998 join => { cd => 'track' },
1999 order_by => 'artist.name',
2003 You need to use the relationship (not the table) name in conditions,
2004 because they are aliased as such. The current table is aliased as "me", so
2005 you need to use me.column_name in order to avoid ambiguity. For example:
2007 # Get CDs from 1984 with a 'Foo' track
2008 my $rs = $schema->resultset('CD')->search(
2011 'tracks.name' => 'Foo'
2013 { join => 'tracks' }
2016 If the same join is supplied twice, it will be aliased to <rel>_2 (and
2017 similarly for a third time). For e.g.
2019 my $rs = $schema->resultset('Artist')->search({
2020 'cds.title' => 'Down to Earth',
2021 'cds_2.title' => 'Popular',
2023 join => [ qw/cds cds/ ],
2026 will return a set of all artists that have both a cd with title 'Down
2027 to Earth' and a cd with title 'Popular'.
2029 If you want to fetch related objects from other tables as well, see C<prefetch>
2036 =item Value: ($rel_name | \@rel_names | \%rel_names)
2040 Contains one or more relationships that should be fetched along with the main
2041 query (when they are accessed afterwards they will have already been
2042 "prefetched"). This is useful for when you know you will need the related
2043 objects, because it saves at least one query:
2045 my $rs = $schema->resultset('Tag')->search(
2054 The initial search results in SQL like the following:
2056 SELECT tag.*, cd.*, artist.* FROM tag
2057 JOIN cd ON tag.cd = cd.cdid
2058 JOIN artist ON cd.artist = artist.artistid
2060 L<DBIx::Class> has no need to go back to the database when we access the
2061 C<cd> or C<artist> relationships, which saves us two SQL statements in this
2064 Simple prefetches will be joined automatically, so there is no need
2065 for a C<join> attribute in the above search. If you're prefetching to
2066 depth (e.g. { cd => { artist => 'label' } or similar), you'll need to
2067 specify the join as well.
2069 C<prefetch> can be used with the following relationship types: C<belongs_to>,
2070 C<has_one> (or if you're using C<add_relationship>, any relationship declared
2071 with an accessor type of 'single' or 'filter').
2081 Makes the resultset paged and specifies the page to retrieve. Effectively
2082 identical to creating a non-pages resultset and then calling ->page($page)
2085 If L<rows> attribute is not specified it defualts to 10 rows per page.
2095 Specifes the maximum number of rows for direct retrieval or the number of
2096 rows per page if the page attribute or method is used.
2102 =item Value: $offset
2106 Specifies the (zero-based) row number for the first row to be returned, or the
2107 of the first row of the first page if paging is used.
2113 =item Value: \@columns
2117 A arrayref of columns to group by. Can include columns of joined tables.
2119 group_by => [qw/ column1 column2 ... /]
2125 =item Value: $condition
2129 HAVING is a select statement attribute that is applied between GROUP BY and
2130 ORDER BY. It is applied to the after the grouping calculations have been
2133 having => { 'count(employee)' => { '>=', 100 } }
2139 =item Value: (0 | 1)
2143 Set to 1 to group by all columns.
2149 Adds to the WHERE clause.
2151 # only return rows WHERE deleted IS NULL for all searches
2152 __PACKAGE__->resultset_attributes({ where => { deleted => undef } }); )
2154 Can be overridden by passing C<{ where => undef }> as an attribute
2161 Set to 1 to cache search results. This prevents extra SQL queries if you
2162 revisit rows in your ResultSet:
2164 my $resultset = $schema->resultset('Artist')->search( undef, { cache => 1 } );
2166 while( my $artist = $resultset->next ) {
2170 $rs->first; # without cache, this would issue a query
2172 By default, searches are not cached.
2174 For more examples of using these attributes, see
2175 L<DBIx::Class::Manual::Cookbook>.
2181 =item Value: \@from_clause
2185 The C<from> attribute gives you manual control over the C<FROM> clause of SQL
2186 statements generated by L<DBIx::Class>, allowing you to express custom C<JOIN>
2189 NOTE: Use this on your own risk. This allows you to shoot off your foot!
2191 C<join> will usually do what you need and it is strongly recommended that you
2192 avoid using C<from> unless you cannot achieve the desired result using C<join>.
2193 And we really do mean "cannot", not just tried and failed. Attempting to use
2194 this because you're having problems with C<join> is like trying to use x86
2195 ASM because you've got a syntax error in your C. Trust us on this.
2197 Now, if you're still really, really sure you need to use this (and if you're
2198 not 100% sure, ask the mailing list first), here's an explanation of how this
2201 The syntax is as follows -
2204 { <alias1> => <table1> },
2206 { <alias2> => <table2>, -join_type => 'inner|left|right' },
2207 [], # nested JOIN (optional)
2208 { <table1.column1> => <table2.column2>, ... (more conditions) },
2210 # More of the above [ ] may follow for additional joins
2217 ON <table1.column1> = <table2.column2>
2218 <more joins may follow>
2220 An easy way to follow the examples below is to remember the following:
2222 Anything inside "[]" is a JOIN
2223 Anything inside "{}" is a condition for the enclosing JOIN
2225 The following examples utilize a "person" table in a family tree application.
2226 In order to express parent->child relationships, this table is self-joined:
2228 # Person->belongs_to('father' => 'Person');
2229 # Person->belongs_to('mother' => 'Person');
2231 C<from> can be used to nest joins. Here we return all children with a father,
2232 then search against all mothers of those children:
2234 $rs = $schema->resultset('Person')->search(
2237 alias => 'mother', # alias columns in accordance with "from"
2239 { mother => 'person' },
2242 { child => 'person' },
2244 { father => 'person' },
2245 { 'father.person_id' => 'child.father_id' }
2248 { 'mother.person_id' => 'child.mother_id' }
2255 # SELECT mother.* FROM person mother
2258 # JOIN person father
2259 # ON ( father.person_id = child.father_id )
2261 # ON ( mother.person_id = child.mother_id )
2263 The type of any join can be controlled manually. To search against only people
2264 with a father in the person table, we could explicitly use C<INNER JOIN>:
2266 $rs = $schema->resultset('Person')->search(
2269 alias => 'child', # alias columns in accordance with "from"
2271 { child => 'person' },
2273 { father => 'person', -join_type => 'inner' },
2274 { 'father.id' => 'child.father_id' }
2281 # SELECT child.* FROM person child
2282 # INNER JOIN person father ON child.father_id = father.id