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 _source_handle => $source,
102 result_class => $attrs->{result_class} || $source->resolve->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 my $alias = $self->{attrs}{alias};
838 foreach my $const (@const_rows) {
839 scalar @const_keys or do {
840 @const_keys = sort { length($a) <=> length($b) } keys %$const;
842 foreach my $key (@const_keys) {
845 my @parts = split(/\./, $key);
847 my $data = $const->{$key};
848 foreach my $p (@parts) {
849 $target = $target->[1]->{$p} ||= [];
851 if ($cur eq ".${key}" && (my @ckey = @{$collapse{$cur}||[]})) {
852 # collapsing at this point and on final part
853 my $pos = $collapse_pos{$cur};
854 CK: foreach my $ck (@ckey) {
855 if (!defined $pos->{$ck} || $pos->{$ck} ne $data->{$ck}) {
856 $collapse_pos{$cur} = $data;
857 delete @collapse_pos{ # clear all positioning for sub-entries
858 grep { m/^\Q${cur}.\E/ } keys %collapse_pos
865 if (exists $collapse{$cur}) {
866 $target = $target->[-1];
869 $target->[0] = $data;
871 $info->[0] = $const->{$key};
883 =item Arguments: $result_source?
885 =item Return Value: $result_source
889 An accessor for the primary ResultSource object from which this ResultSet
896 =item Arguments: $result_class?
898 =item Return Value: $result_class
902 An accessor for the class to use when creating row objects. Defaults to
903 C<< result_source->result_class >> - which in most cases is the name of the
904 L<"table"|DBIx::Class::Manual::Glossary/"ResultSource"> class.
913 =item Arguments: $cond, \%attrs??
915 =item Return Value: $count
919 Performs an SQL C<COUNT> with the same query as the resultset was built
920 with to find the number of elements. If passed arguments, does a search
921 on the resultset and counts the results of that.
923 Note: When using C<count> with C<group_by>, L<DBIX::Class> emulates C<GROUP BY>
924 using C<COUNT( DISTINCT( columns ) )>. Some databases (notably SQLite) do
925 not support C<DISTINCT> with multiple columns. If you are using such a
926 database, you should only use columns from the main table in your C<group_by>
933 return $self->search(@_)->count if @_ and defined $_[0];
934 return scalar @{ $self->get_cache } if $self->get_cache;
935 my $count = $self->_count;
936 return 0 unless $count;
938 $count -= $self->{attrs}{offset} if $self->{attrs}{offset};
939 $count = $self->{attrs}{rows} if
940 $self->{attrs}{rows} and $self->{attrs}{rows} < $count;
944 sub _count { # Separated out so pager can get the full count
946 my $select = { count => '*' };
948 my $attrs = { %{$self->_resolved_attrs} };
949 if (my $group_by = delete $attrs->{group_by}) {
950 delete $attrs->{having};
951 my @distinct = (ref $group_by ? @$group_by : ($group_by));
952 # todo: try CONCAT for multi-column pk
953 my @pk = $self->result_source->primary_columns;
955 my $alias = $attrs->{alias};
956 foreach my $column (@distinct) {
957 if ($column =~ qr/^(?:\Q${alias}.\E)?$pk[0]$/) {
958 @distinct = ($column);
964 $select = { count => { distinct => \@distinct } };
967 $attrs->{select} = $select;
968 $attrs->{as} = [qw/count/];
970 # offset, order by and page are not needed to count. record_filter is cdbi
971 delete $attrs->{$_} for qw/rows offset order_by page pager record_filter/;
973 my $tmp_rs = (ref $self)->new($self->_source_handle, $attrs);
974 my ($count) = $tmp_rs->cursor->next;
982 =item Arguments: $sql_fragment, @bind_values
984 =item Return Value: $count
988 Counts the results in a literal query. Equivalent to calling L</search_literal>
989 with the passed arguments, then L</count>.
993 sub count_literal { shift->search_literal(@_)->count; }
999 =item Arguments: none
1001 =item Return Value: @objects
1005 Returns all elements in the resultset. Called implicitly if the resultset
1006 is returned in list context.
1012 return @{ $self->get_cache } if $self->get_cache;
1016 # TODO: don't call resolve here
1017 if (keys %{$self->_resolved_attrs->{collapse}}) {
1018 # if ($self->{attrs}{prefetch}) {
1019 # Using $self->cursor->all is really just an optimisation.
1020 # If we're collapsing has_many prefetches it probably makes
1021 # very little difference, and this is cleaner than hacking
1022 # _construct_object to survive the approach
1023 my @row = $self->cursor->next;
1025 push(@obj, $self->_construct_object(@row));
1026 @row = (exists $self->{stashed_row}
1027 ? @{delete $self->{stashed_row}}
1028 : $self->cursor->next);
1031 @obj = map { $self->_construct_object(@$_) } $self->cursor->all;
1034 $self->set_cache(\@obj) if $self->{attrs}{cache};
1042 =item Arguments: none
1044 =item Return Value: $self
1048 Resets the resultset's cursor, so you can iterate through the elements again.
1054 delete $self->{_attrs} if exists $self->{_attrs};
1055 $self->{all_cache_position} = 0;
1056 $self->cursor->reset;
1064 =item Arguments: none
1066 =item Return Value: $object?
1070 Resets the resultset and returns an object for the first result (if the
1071 resultset returns anything).
1076 return $_[0]->reset->next;
1079 # _cond_for_update_delete
1081 # update/delete require the condition to be modified to handle
1082 # the differing SQL syntax available. This transforms the $self->{cond}
1083 # appropriately, returning the new condition.
1085 sub _cond_for_update_delete {
1086 my ($self, $full_cond) = @_;
1089 $full_cond ||= $self->{cond};
1090 # No-op. No condition, we're updating/deleting everything
1091 return $cond unless ref $full_cond;
1093 if (ref $full_cond eq 'ARRAY') {
1097 foreach my $key (keys %{$_}) {
1099 $hash{$1} = $_->{$key};
1105 elsif (ref $full_cond eq 'HASH') {
1106 if ((keys %{$full_cond})[0] eq '-and') {
1109 my @cond = @{$full_cond->{-and}};
1110 for (my $i = 0; $i < @cond; $i++) {
1111 my $entry = $cond[$i];
1114 if (ref $entry eq 'HASH') {
1115 $hash = $self->_cond_for_update_delete($entry);
1118 $entry =~ /([^.]+)$/;
1119 $hash->{$1} = $cond[++$i];
1122 push @{$cond->{-and}}, $hash;
1126 foreach my $key (keys %{$full_cond}) {
1128 $cond->{$1} = $full_cond->{$key};
1133 $self->throw_exception(
1134 "Can't update/delete on resultset with condition unless hash or array"
1146 =item Arguments: \%values
1148 =item Return Value: $storage_rv
1152 Sets the specified columns in the resultset to the supplied values in a
1153 single query. Return value will be true if the update succeeded or false
1154 if no records were updated; exact type of success value is storage-dependent.
1159 my ($self, $values) = @_;
1160 $self->throw_exception("Values for update must be a hash")
1161 unless ref $values eq 'HASH';
1163 my $cond = $self->_cond_for_update_delete;
1165 return $self->result_source->storage->update(
1166 $self->result_source, $values, $cond
1174 =item Arguments: \%values
1176 =item Return Value: 1
1180 Fetches all objects and updates them one at a time. Note that C<update_all>
1181 will run DBIC cascade triggers, while L</update> will not.
1186 my ($self, $values) = @_;
1187 $self->throw_exception("Values for update must be a hash")
1188 unless ref $values eq 'HASH';
1189 foreach my $obj ($self->all) {
1190 $obj->set_columns($values)->update;
1199 =item Arguments: none
1201 =item Return Value: 1
1205 Deletes the contents of the resultset from its result source. Note that this
1206 will not run DBIC cascade triggers. See L</delete_all> if you need triggers
1207 to run. See also L<DBIx::Class::Row/delete>.
1214 my $cond = $self->_cond_for_update_delete;
1216 $self->result_source->storage->delete($self->result_source, $cond);
1224 =item Arguments: none
1226 =item Return Value: 1
1230 Fetches all objects and deletes them one at a time. Note that C<delete_all>
1231 will run DBIC cascade triggers, while L</delete> will not.
1237 $_->delete for $self->all;
1245 =item Arguments: none
1247 =item Return Value: $pager
1251 Return Value a L<Data::Page> object for the current resultset. Only makes
1252 sense for queries with a C<page> attribute.
1258 my $attrs = $self->{attrs};
1259 $self->throw_exception("Can't create pager for non-paged rs")
1260 unless $self->{attrs}{page};
1261 $attrs->{rows} ||= 10;
1262 return $self->{pager} ||= Data::Page->new(
1263 $self->_count, $attrs->{rows}, $self->{attrs}{page});
1270 =item Arguments: $page_number
1272 =item Return Value: $rs
1276 Returns a resultset for the $page_number page of the resultset on which page
1277 is called, where each page contains a number of rows equal to the 'rows'
1278 attribute set on the resultset (10 by default).
1283 my ($self, $page) = @_;
1284 return (ref $self)->new($self->_source_handle, { %{$self->{attrs}}, page => $page });
1291 =item Arguments: \%vals
1293 =item Return Value: $object
1297 Creates an object in the resultset's result class and returns it.
1302 my ($self, $values) = @_;
1303 $self->throw_exception( "new_result needs a hash" )
1304 unless (ref $values eq 'HASH');
1305 $self->throw_exception(
1306 "Can't abstract implicit construct, condition not a hash"
1307 ) if ($self->{cond} && !(ref $self->{cond} eq 'HASH'));
1309 my $alias = $self->{attrs}{alias};
1310 my $collapsed_cond = $self->{cond} ? $self->_collapse_cond($self->{cond}) : {};
1312 %{ $self->_remove_alias($values, $alias) },
1313 %{ $self->_remove_alias($collapsed_cond, $alias) },
1314 -source_handle => $self->_source_handle
1317 return $self->result_class->new(\%new);
1322 # Recursively collapse the condition.
1324 sub _collapse_cond {
1325 my ($self, $cond, $collapsed) = @_;
1329 if (ref $cond eq 'ARRAY') {
1330 foreach my $subcond (@$cond) {
1331 next unless ref $subcond; # -or
1332 # warn "ARRAY: " . Dumper $subcond;
1333 $collapsed = $self->_collapse_cond($subcond, $collapsed);
1336 elsif (ref $cond eq 'HASH') {
1337 if (keys %$cond and (keys %$cond)[0] eq '-and') {
1338 foreach my $subcond (@{$cond->{-and}}) {
1339 # warn "HASH: " . Dumper $subcond;
1340 $collapsed = $self->_collapse_cond($subcond, $collapsed);
1344 # warn "LEAF: " . Dumper $cond;
1345 foreach my $col (keys %$cond) {
1346 my $value = $cond->{$col};
1347 $collapsed->{$col} = $value;
1357 # Remove the specified alias from the specified query hash. A copy is made so
1358 # the original query is not modified.
1361 my ($self, $query, $alias) = @_;
1363 my %orig = %{ $query || {} };
1366 foreach my $key (keys %orig) {
1368 $unaliased{$key} = $orig{$key};
1371 $unaliased{$1} = $orig{$key}
1372 if $key =~ m/^(?:\Q$alias\E\.)?([^.]+)$/;
1382 =item Arguments: \%vals, \%attrs?
1384 =item Return Value: $object
1388 Find an existing record from this resultset. If none exists, instantiate a new
1389 result object and return it. The object will not be saved into your storage
1390 until you call L<DBIx::Class::Row/insert> on it.
1392 If you want objects to be saved immediately, use L</find_or_create> instead.
1398 my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {});
1399 my $hash = ref $_[0] eq 'HASH' ? shift : {@_};
1400 my $exists = $self->find($hash, $attrs);
1401 return defined $exists ? $exists : $self->new_result($hash);
1408 =item Arguments: \%vals
1410 =item Return Value: $object
1414 Inserts a record into the resultset and returns the object representing it.
1416 Effectively a shortcut for C<< ->new_result(\%vals)->insert >>.
1421 my ($self, $attrs) = @_;
1422 $self->throw_exception( "create needs a hashref" )
1423 unless ref $attrs eq 'HASH';
1424 return $self->new_result($attrs)->insert;
1427 =head2 find_or_create
1431 =item Arguments: \%vals, \%attrs?
1433 =item Return Value: $object
1437 $class->find_or_create({ key => $val, ... });
1439 Tries to find a record based on its primary key or unique constraint; if none
1440 is found, creates one and returns that instead.
1442 my $cd = $schema->resultset('CD')->find_or_create({
1444 artist => 'Massive Attack',
1445 title => 'Mezzanine',
1449 Also takes an optional C<key> attribute, to search by a specific key or unique
1450 constraint. For example:
1452 my $cd = $schema->resultset('CD')->find_or_create(
1454 artist => 'Massive Attack',
1455 title => 'Mezzanine',
1457 { key => 'cd_artist_title' }
1460 See also L</find> and L</update_or_create>. For information on how to declare
1461 unique constraints, see L<DBIx::Class::ResultSource/add_unique_constraint>.
1465 sub find_or_create {
1467 my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {});
1468 my $hash = ref $_[0] eq 'HASH' ? shift : {@_};
1469 my $exists = $self->find($hash, $attrs);
1470 return defined $exists ? $exists : $self->create($hash);
1473 =head2 update_or_create
1477 =item Arguments: \%col_values, { key => $unique_constraint }?
1479 =item Return Value: $object
1483 $class->update_or_create({ col => $val, ... });
1485 First, searches for an existing row matching one of the unique constraints
1486 (including the primary key) on the source of this resultset. If a row is
1487 found, updates it with the other given column values. Otherwise, creates a new
1490 Takes an optional C<key> attribute to search on a specific unique constraint.
1493 # In your application
1494 my $cd = $schema->resultset('CD')->update_or_create(
1496 artist => 'Massive Attack',
1497 title => 'Mezzanine',
1500 { key => 'cd_artist_title' }
1503 If no C<key> is specified, it searches on all unique constraints defined on the
1504 source, including the primary key.
1506 If the C<key> is specified as C<primary>, it searches only on the primary key.
1508 See also L</find> and L</find_or_create>. For information on how to declare
1509 unique constraints, see L<DBIx::Class::ResultSource/add_unique_constraint>.
1513 sub update_or_create {
1515 my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {});
1516 my $cond = ref $_[0] eq 'HASH' ? shift : {@_};
1518 my $row = $self->find($cond, $attrs);
1520 $row->update($cond);
1524 return $self->create($cond);
1531 =item Arguments: none
1533 =item Return Value: \@cache_objects?
1537 Gets the contents of the cache for the resultset, if the cache is set.
1549 =item Arguments: \@cache_objects
1551 =item Return Value: \@cache_objects
1555 Sets the contents of the cache for the resultset. Expects an arrayref
1556 of objects of the same class as those produced by the resultset. Note that
1557 if the cache is set the resultset will return the cached objects rather
1558 than re-querying the database even if the cache attr is not set.
1563 my ( $self, $data ) = @_;
1564 $self->throw_exception("set_cache requires an arrayref")
1565 if defined($data) && (ref $data ne 'ARRAY');
1566 $self->{all_cache} = $data;
1573 =item Arguments: none
1575 =item Return Value: []
1579 Clears the cache for the resultset.
1584 shift->set_cache(undef);
1587 =head2 related_resultset
1591 =item Arguments: $relationship_name
1593 =item Return Value: $resultset
1597 Returns a related resultset for the supplied relationship name.
1599 $artist_rs = $schema->resultset('CD')->related_resultset('Artist');
1603 sub related_resultset {
1604 my ($self, $rel) = @_;
1606 $self->{related_resultsets} ||= {};
1607 return $self->{related_resultsets}{$rel} ||= do {
1608 my $rel_obj = $self->result_source->relationship_info($rel);
1610 $self->throw_exception(
1611 "search_related: result source '" . $self->_source_handle->source_moniker .
1612 "' has no such relationship $rel")
1615 my ($from,$seen) = $self->_resolve_from($rel);
1617 my $join_count = $seen->{$rel};
1618 my $alias = ($join_count > 1 ? join('_', $rel, $join_count) : $rel);
1620 $self->_source_handle->schema->resultset($rel_obj->{class})->search_rs(
1622 %{$self->{attrs}||{}},
1628 where => $self->{cond},
1636 my ($self, $extra_join) = @_;
1637 my $source = $self->result_source;
1638 my $attrs = $self->{attrs};
1640 my $from = $attrs->{from}
1641 || [ { $attrs->{alias} => $source->from } ];
1643 my $seen = { %{$attrs->{seen_join}||{}} };
1645 my $join = ($attrs->{join}
1646 ? [ $attrs->{join}, $extra_join ]
1650 ($join ? $source->resolve_join($join, $attrs->{alias}, $seen) : ()),
1653 return ($from,$seen);
1656 sub _resolved_attrs {
1658 return $self->{_attrs} if $self->{_attrs};
1660 my $attrs = { %{$self->{attrs}||{}} };
1661 my $source = $self->result_source;
1662 my $alias = $attrs->{alias};
1664 $attrs->{columns} ||= delete $attrs->{cols} if exists $attrs->{cols};
1665 if ($attrs->{columns}) {
1666 delete $attrs->{as};
1667 } elsif (!$attrs->{select}) {
1668 $attrs->{columns} = [ $source->columns ];
1673 ? (ref $attrs->{select} eq 'ARRAY'
1674 ? [ @{$attrs->{select}} ]
1675 : [ $attrs->{select} ])
1676 : [ map { m/\./ ? $_ : "${alias}.$_" } @{delete $attrs->{columns}} ]
1680 ? (ref $attrs->{as} eq 'ARRAY'
1681 ? [ @{$attrs->{as}} ]
1683 : [ map { m/^\Q${alias}.\E(.+)$/ ? $1 : $_ } @{$attrs->{select}} ]
1687 if ($adds = delete $attrs->{include_columns}) {
1688 $adds = [$adds] unless ref $adds eq 'ARRAY';
1689 push(@{$attrs->{select}}, @$adds);
1690 push(@{$attrs->{as}}, map { m/([^.]+)$/; $1 } @$adds);
1692 if ($adds = delete $attrs->{'+select'}) {
1693 $adds = [$adds] unless ref $adds eq 'ARRAY';
1694 push(@{$attrs->{select}},
1695 map { /\./ || ref $_ ? $_ : "${alias}.$_" } @$adds);
1697 if (my $adds = delete $attrs->{'+as'}) {
1698 $adds = [$adds] unless ref $adds eq 'ARRAY';
1699 push(@{$attrs->{as}}, @$adds);
1702 $attrs->{from} ||= [ { 'me' => $source->from } ];
1704 if (exists $attrs->{join} || exists $attrs->{prefetch}) {
1705 my $join = delete $attrs->{join} || {};
1707 if (defined $attrs->{prefetch}) {
1708 $join = $self->_merge_attr(
1709 $join, $attrs->{prefetch}
1713 $attrs->{from} = # have to copy here to avoid corrupting the original
1716 $source->resolve_join($join, $alias, { %{$attrs->{seen_join}||{}} })
1720 $attrs->{group_by} ||= $attrs->{select} if delete $attrs->{distinct};
1721 if ($attrs->{order_by}) {
1722 $attrs->{order_by} = (ref($attrs->{order_by}) eq 'ARRAY'
1723 ? [ @{$attrs->{order_by}} ]
1724 : [ $attrs->{order_by} ]);
1726 $attrs->{order_by} = [];
1729 my $collapse = $attrs->{collapse} || {};
1730 if (my $prefetch = delete $attrs->{prefetch}) {
1731 $prefetch = $self->_merge_attr({}, $prefetch);
1733 my $seen = $attrs->{seen_join} || {};
1734 foreach my $p (ref $prefetch eq 'ARRAY' ? @$prefetch : ($prefetch)) {
1735 # bring joins back to level of current class
1736 my @prefetch = $source->resolve_prefetch(
1737 $p, $alias, $seen, \@pre_order, $collapse
1739 push(@{$attrs->{select}}, map { $_->[0] } @prefetch);
1740 push(@{$attrs->{as}}, map { $_->[1] } @prefetch);
1742 push(@{$attrs->{order_by}}, @pre_order);
1744 $attrs->{collapse} = $collapse;
1746 return $self->{_attrs} = $attrs;
1750 my ($self, $a, $b) = @_;
1751 return $b unless defined($a);
1752 return $a unless defined($b);
1754 if (ref $b eq 'HASH' && ref $a eq 'HASH') {
1755 foreach my $key (keys %{$b}) {
1756 if (exists $a->{$key}) {
1757 $a->{$key} = $self->_merge_attr($a->{$key}, $b->{$key});
1759 $a->{$key} = $b->{$key};
1764 $a = [$a] unless ref $a eq 'ARRAY';
1765 $b = [$b] unless ref $b eq 'ARRAY';
1769 foreach my $x ($a, $b) {
1770 foreach my $element (@{$x}) {
1771 if (ref $element eq 'HASH') {
1772 $hash = $self->_merge_attr($hash, $element);
1773 } elsif (ref $element eq 'ARRAY') {
1774 push(@array, @{$element});
1776 push(@array, $element) unless $b == $x
1777 && grep { $_ eq $element } @array;
1782 @array = grep { !exists $hash->{$_} } @array;
1784 return keys %{$hash}
1797 $self->_source_handle($_[0]->handle);
1799 $self->_source_handle->resolve;
1803 =head2 throw_exception
1805 See L<DBIx::Class::Schema/throw_exception> for details.
1809 sub throw_exception {
1811 $self->_source_handle->schema->throw_exception(@_);
1814 # XXX: FIXME: Attributes docs need clearing up
1818 The resultset takes various attributes that modify its behavior. Here's an
1825 =item Value: ($order_by | \@order_by)
1829 Which column(s) to order the results by. This is currently passed
1830 through directly to SQL, so you can give e.g. C<year DESC> for a
1831 descending order on the column `year'.
1833 Please note that if you have C<quote_char> enabled (see
1834 L<DBIx::Class::Storage::DBI/connect_info>) you will need to do C<\'year DESC' > to
1835 specify an order. (The scalar ref causes it to be passed as raw sql to the DB,
1836 so you will need to manually quote things as appropriate.)
1842 =item Value: \@columns
1846 Shortcut to request a particular set of columns to be retrieved. Adds
1847 C<me.> onto the start of any column without a C<.> in it and sets C<select>
1848 from that, then auto-populates C<as> from C<select> as normal. (You may also
1849 use the C<cols> attribute, as in earlier versions of DBIC.)
1851 =head2 include_columns
1855 =item Value: \@columns
1859 Shortcut to include additional columns in the returned results - for example
1861 $schema->resultset('CD')->search(undef, {
1862 include_columns => ['artist.name'],
1866 would return all CDs and include a 'name' column to the information
1867 passed to object inflation. Note that the 'artist' is the name of the
1868 column (or relationship) accessor, and 'name' is the name of the column
1869 accessor in the related table.
1875 =item Value: \@select_columns
1879 Indicates which columns should be selected from the storage. You can use
1880 column names, or in the case of RDBMS back ends, function or stored procedure
1883 $rs = $schema->resultset('Employee')->search(undef, {
1886 { count => 'employeeid' },
1891 When you use function/stored procedure names and do not supply an C<as>
1892 attribute, the column names returned are storage-dependent. E.g. MySQL would
1893 return a column named C<count(employeeid)> in the above example.
1899 Indicates additional columns to be selected from storage. Works the same as
1900 L<select> but adds columns to the selection.
1908 Indicates additional column names for those added via L<+select>.
1916 =item Value: \@inflation_names
1920 Indicates column names for object inflation. That is, c< as >
1921 indicates the name that the column can be accessed as via the
1922 C<get_column> method (or via the object accessor, B<if one already
1923 exists>). It has nothing to do with the SQL code C< SELECT foo AS bar
1926 The C< as > attribute is used in conjunction with C<select>,
1927 usually when C<select> contains one or more function or stored
1930 $rs = $schema->resultset('Employee')->search(undef, {
1933 { count => 'employeeid' }
1935 as => ['name', 'employee_count'],
1938 my $employee = $rs->first(); # get the first Employee
1940 If the object against which the search is performed already has an accessor
1941 matching a column name specified in C<as>, the value can be retrieved using
1942 the accessor as normal:
1944 my $name = $employee->name();
1946 If on the other hand an accessor does not exist in the object, you need to
1947 use C<get_column> instead:
1949 my $employee_count = $employee->get_column('employee_count');
1951 You can create your own accessors if required - see
1952 L<DBIx::Class::Manual::Cookbook> for details.
1954 Please note: This will NOT insert an C<AS employee_count> into the SQL
1955 statement produced, it is used for internal access only. Thus
1956 attempting to use the accessor in an C<order_by> clause or similar
1957 will fail miserably.
1959 To get around this limitation, you can supply literal SQL to your
1960 C<select> attibute that contains the C<AS alias> text, eg:
1962 select => [\'myfield AS alias']
1968 =item Value: ($rel_name | \@rel_names | \%rel_names)
1972 Contains a list of relationships that should be joined for this query. For
1975 # Get CDs by Nine Inch Nails
1976 my $rs = $schema->resultset('CD')->search(
1977 { 'artist.name' => 'Nine Inch Nails' },
1978 { join => 'artist' }
1981 Can also contain a hash reference to refer to the other relation's relations.
1984 package MyApp::Schema::Track;
1985 use base qw/DBIx::Class/;
1986 __PACKAGE__->table('track');
1987 __PACKAGE__->add_columns(qw/trackid cd position title/);
1988 __PACKAGE__->set_primary_key('trackid');
1989 __PACKAGE__->belongs_to(cd => 'MyApp::Schema::CD');
1992 # In your application
1993 my $rs = $schema->resultset('Artist')->search(
1994 { 'track.title' => 'Teardrop' },
1996 join => { cd => 'track' },
1997 order_by => 'artist.name',
2001 You need to use the relationship (not the table) name in conditions,
2002 because they are aliased as such. The current table is aliased as "me", so
2003 you need to use me.column_name in order to avoid ambiguity. For example:
2005 # Get CDs from 1984 with a 'Foo' track
2006 my $rs = $schema->resultset('CD')->search(
2009 'tracks.name' => 'Foo'
2011 { join => 'tracks' }
2014 If the same join is supplied twice, it will be aliased to <rel>_2 (and
2015 similarly for a third time). For e.g.
2017 my $rs = $schema->resultset('Artist')->search({
2018 'cds.title' => 'Down to Earth',
2019 'cds_2.title' => 'Popular',
2021 join => [ qw/cds cds/ ],
2024 will return a set of all artists that have both a cd with title 'Down
2025 to Earth' and a cd with title 'Popular'.
2027 If you want to fetch related objects from other tables as well, see C<prefetch>
2034 =item Value: ($rel_name | \@rel_names | \%rel_names)
2038 Contains one or more relationships that should be fetched along with the main
2039 query (when they are accessed afterwards they will have already been
2040 "prefetched"). This is useful for when you know you will need the related
2041 objects, because it saves at least one query:
2043 my $rs = $schema->resultset('Tag')->search(
2052 The initial search results in SQL like the following:
2054 SELECT tag.*, cd.*, artist.* FROM tag
2055 JOIN cd ON tag.cd = cd.cdid
2056 JOIN artist ON cd.artist = artist.artistid
2058 L<DBIx::Class> has no need to go back to the database when we access the
2059 C<cd> or C<artist> relationships, which saves us two SQL statements in this
2062 Simple prefetches will be joined automatically, so there is no need
2063 for a C<join> attribute in the above search. If you're prefetching to
2064 depth (e.g. { cd => { artist => 'label' } or similar), you'll need to
2065 specify the join as well.
2067 C<prefetch> can be used with the following relationship types: C<belongs_to>,
2068 C<has_one> (or if you're using C<add_relationship>, any relationship declared
2069 with an accessor type of 'single' or 'filter').
2079 Makes the resultset paged and specifies the page to retrieve. Effectively
2080 identical to creating a non-pages resultset and then calling ->page($page)
2083 If L<rows> attribute is not specified it defualts to 10 rows per page.
2093 Specifes the maximum number of rows for direct retrieval or the number of
2094 rows per page if the page attribute or method is used.
2100 =item Value: $offset
2104 Specifies the (zero-based) row number for the first row to be returned, or the
2105 of the first row of the first page if paging is used.
2111 =item Value: \@columns
2115 A arrayref of columns to group by. Can include columns of joined tables.
2117 group_by => [qw/ column1 column2 ... /]
2123 =item Value: $condition
2127 HAVING is a select statement attribute that is applied between GROUP BY and
2128 ORDER BY. It is applied to the after the grouping calculations have been
2131 having => { 'count(employee)' => { '>=', 100 } }
2137 =item Value: (0 | 1)
2141 Set to 1 to group by all columns.
2147 Adds to the WHERE clause.
2149 # only return rows WHERE deleted IS NULL for all searches
2150 __PACKAGE__->resultset_attributes({ where => { deleted => undef } }); )
2152 Can be overridden by passing C<{ where => undef }> as an attribute
2159 Set to 1 to cache search results. This prevents extra SQL queries if you
2160 revisit rows in your ResultSet:
2162 my $resultset = $schema->resultset('Artist')->search( undef, { cache => 1 } );
2164 while( my $artist = $resultset->next ) {
2168 $rs->first; # without cache, this would issue a query
2170 By default, searches are not cached.
2172 For more examples of using these attributes, see
2173 L<DBIx::Class::Manual::Cookbook>.
2179 =item Value: \@from_clause
2183 The C<from> attribute gives you manual control over the C<FROM> clause of SQL
2184 statements generated by L<DBIx::Class>, allowing you to express custom C<JOIN>
2187 NOTE: Use this on your own risk. This allows you to shoot off your foot!
2189 C<join> will usually do what you need and it is strongly recommended that you
2190 avoid using C<from> unless you cannot achieve the desired result using C<join>.
2191 And we really do mean "cannot", not just tried and failed. Attempting to use
2192 this because you're having problems with C<join> is like trying to use x86
2193 ASM because you've got a syntax error in your C. Trust us on this.
2195 Now, if you're still really, really sure you need to use this (and if you're
2196 not 100% sure, ask the mailing list first), here's an explanation of how this
2199 The syntax is as follows -
2202 { <alias1> => <table1> },
2204 { <alias2> => <table2>, -join_type => 'inner|left|right' },
2205 [], # nested JOIN (optional)
2206 { <table1.column1> => <table2.column2>, ... (more conditions) },
2208 # More of the above [ ] may follow for additional joins
2215 ON <table1.column1> = <table2.column2>
2216 <more joins may follow>
2218 An easy way to follow the examples below is to remember the following:
2220 Anything inside "[]" is a JOIN
2221 Anything inside "{}" is a condition for the enclosing JOIN
2223 The following examples utilize a "person" table in a family tree application.
2224 In order to express parent->child relationships, this table is self-joined:
2226 # Person->belongs_to('father' => 'Person');
2227 # Person->belongs_to('mother' => 'Person');
2229 C<from> can be used to nest joins. Here we return all children with a father,
2230 then search against all mothers of those children:
2232 $rs = $schema->resultset('Person')->search(
2235 alias => 'mother', # alias columns in accordance with "from"
2237 { mother => 'person' },
2240 { child => 'person' },
2242 { father => 'person' },
2243 { 'father.person_id' => 'child.father_id' }
2246 { 'mother.person_id' => 'child.mother_id' }
2253 # SELECT mother.* FROM person mother
2256 # JOIN person father
2257 # ON ( father.person_id = child.father_id )
2259 # ON ( mother.person_id = child.mother_id )
2261 The type of any join can be controlled manually. To search against only people
2262 with a father in the person table, we could explicitly use C<INNER JOIN>:
2264 $rs = $schema->resultset('Person')->search(
2267 alias => 'child', # alias columns in accordance with "from"
2269 { child => 'person' },
2271 { father => 'person', -join_type => 'inner' },
2272 { 'father.id' => 'child.father_id' }
2279 # SELECT child.* FROM person child
2280 # INNER JOIN person father ON child.father_id = father.id