X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FResultSet.pm;h=4df3d585cc7c382048e0df46a397d48a47e51ff1;hb=4a28c3401397f015e833a802ddab5d341693f7dd;hp=eae9193ea0ea517f107e11d8607c281b40ef71ef;hpb=df8abd99a70d8d8af5046da841557e1a394b752b;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/ResultSet.pm b/lib/DBIx/Class/ResultSet.pm index eae9193..4df3d58 100644 --- a/lib/DBIx/Class/ResultSet.pm +++ b/lib/DBIx/Class/ResultSet.pm @@ -2,10 +2,13 @@ package DBIx::Class::ResultSet; use strict; use warnings; +use Carp qw/croak/; use overload '0+' => 'count', + 'bool' => sub { 1; }, fallback => 1; use Data::Page; +use Storable; =head1 NAME @@ -13,82 +16,274 @@ DBIx::Class::ResultSet - Responsible for fetching and creating resultset. =head1 SYNOPSIS -my $rs = MyApp::DB::Class->search(registered => 1); -my @rows = MyApp::DB::Class->search(foo => 'bar'); + my $rs = $schema->resultset('User')->search(registered => 1); + my @rows = $schema->resultset('Foo')->search(bar => 'baz'); =head1 DESCRIPTION The resultset is also known as an iterator. It is responsible for handling -queries that may return an arbitrary number of rows, e.g. via C +queries that may return an arbitrary number of rows, e.g. via L or a C relationship. +In the examples below, the following table classes are used: + + package MyApp::Schema::Artist; + use base qw/DBIx::Class/; + __PACKAGE__->table('artist'); + __PACKAGE__->add_columns(qw/artistid name/); + __PACKAGE__->set_primary_key('artistid'); + __PACKAGE__->has_many(cds => 'MyApp::Schema::CD'); + 1; + + package MyApp::Schema::CD; + use base qw/DBIx::Class/; + __PACKAGE__->table('artist'); + __PACKAGE__->add_columns(qw/cdid artist title year/); + __PACKAGE__->set_primary_key('cdid'); + __PACKAGE__->belongs_to(artist => 'MyApp::Schema::Artist'); + 1; + =head1 METHODS -=head2 new($db_class, \%$attrs) +=head2 new($source, \%$attrs) -The resultset constructor. Takes a table class and an attribute hash -(see below for more information on attributes). Does not perform -any queries -- these are executed as needed by the other methods. +The resultset constructor. Takes a source object (usually a +L) and an attribute hash (see L +below). Does not perform any queries -- these are executed as needed by the +other methods. + +Generally you won't need to construct a resultset manually. You'll +automatically get one from e.g. a L called in scalar context: + + my $rs = $schema->resultset('CD')->search({ title => '100th Window' }); =cut sub new { - my ($it_class, $db_class, $attrs) = @_; - #use Data::Dumper; warn Dumper(@_); - $it_class = ref $it_class if ref $it_class; - $attrs = { %{ $attrs || {} } }; + my $class = shift; + return $class->new_result(@_) if ref $class; + my ($source, $attrs) = @_; + #use Data::Dumper; warn Dumper($attrs); + $attrs = Storable::dclone($attrs || {}); # { %{ $attrs || {} } }; my %seen; - $attrs->{cols} ||= [ map { "me.$_" } $db_class->_select_columns ]; - $attrs->{from} ||= [ { 'me' => $db_class->_table_name } ]; - if ($attrs->{join}) { - foreach my $j (ref $attrs->{join} eq 'ARRAY' - ? (@{$attrs->{join}}) : ($attrs->{join})) { + my $alias = ($attrs->{alias} ||= 'me'); + if ($attrs->{cols} || !$attrs->{select}) { + delete $attrs->{as} if $attrs->{cols}; + my @cols = ($attrs->{cols} + ? @{delete $attrs->{cols}} + : $source->columns); + $attrs->{select} = [ map { m/\./ ? $_ : "${alias}.$_" } @cols ]; + } + $attrs->{as} ||= [ map { m/^$alias\.(.*)$/ ? $1 : $_ } @{$attrs->{select}} ]; + #use Data::Dumper; warn Dumper(@{$attrs}{qw/select as/}); + $attrs->{from} ||= [ { $alias => $source->from } ]; + if (my $join = delete $attrs->{join}) { + foreach my $j (ref $join eq 'ARRAY' + ? (@{$join}) : ($join)) { if (ref $j eq 'HASH') { $seen{$_} = 1 foreach keys %$j; } else { $seen{$j} = 1; } } - push(@{$attrs->{from}}, $db_class->_resolve_join($attrs->{join}, 'me')); + push(@{$attrs->{from}}, $source->resolve_join($join, $attrs->{alias})); } - foreach my $pre (@{$attrs->{prefetch} || []}) { - push(@{$attrs->{from}}, $db_class->_resolve_join($pre, 'me')) + $attrs->{group_by} ||= $attrs->{select} if delete $attrs->{distinct}; + foreach my $pre (@{delete $attrs->{prefetch} || []}) { + push(@{$attrs->{from}}, $source->resolve_join($pre, $attrs->{alias})) unless $seen{$pre}; - push(@{$attrs->{cols}}, + my @pre = map { "$pre.$_" } - $db_class->_relationships->{$pre}->{class}->_select_columns); + $source->related_source($pre)->columns; + push(@{$attrs->{select}}, @pre); + push(@{$attrs->{as}}, @pre); + } + if ($attrs->{page}) { + $attrs->{rows} ||= 10; + $attrs->{offset} ||= 0; + $attrs->{offset} += ($attrs->{rows} * ($attrs->{page} - 1)); } my $new = { - class => $db_class, - cols => $attrs->{cols} || [ $db_class->_select_columns ], + source => $source, cond => $attrs->{where}, - from => $attrs->{from} || $db_class->_table_name, + from => $attrs->{from}, count => undef, + page => delete $attrs->{page}, pager => undef, attrs => $attrs }; - bless ($new, $it_class); - $new->pager if ($attrs->{page}); + bless ($new, $class); return $new; } +=head2 search + + my @obj = $rs->search({ foo => 3 }); # "... WHERE foo = 3" + my $new_rs = $rs->search({ foo => 3 }); + +If you need to pass in additional attributes but no additional condition, +call it as C. + + # "SELECT foo, bar FROM $class_table" + my @all = $class->search({}, { cols => [qw/foo bar/] }); + +=cut + +sub search { + my $self = shift; + + #use Data::Dumper;warn Dumper(@_); + + my $attrs = { %{$self->{attrs}} }; + if (@_ > 1 && ref $_[$#_] eq 'HASH') { + $attrs = { %$attrs, %{ pop(@_) } }; + } + + my $where = (@_ ? ((@_ == 1 || ref $_[0] eq "HASH") ? shift : {@_}) : undef()); + if (defined $where) { + $where = (defined $attrs->{where} + ? { '-and' => + [ map { ref $_ eq 'ARRAY' ? [ -or => $_ ] : $_ } + $where, $attrs->{where} ] } + : $where); + $attrs->{where} = $where; + } + + my $rs = (ref $self)->new($self->{source}, $attrs); + + return (wantarray ? $rs->all : $rs); +} + +=head2 search_literal + + my @obj = $rs->search_literal($literal_where_cond, @bind); + my $new_rs = $rs->search_literal($literal_where_cond, @bind); + +Pass a literal chunk of SQL to be added to the conditional part of the +resultset. + +=cut + +sub search_literal { + my ($self, $cond, @vals) = @_; + my $attrs = (ref $vals[$#vals] eq 'HASH' ? { %{ pop(@vals) } } : {}); + $attrs->{bind} = [ @{$self->{attrs}{bind}||[]}, @vals ]; + return $self->search(\$cond, $attrs); +} + +=head2 find(@colvalues), find(\%cols, \%attrs?) + +Finds a row based on its primary key or unique constraint. For example: + + my $cd = $schema->resultset('CD')->find(5); + +Also takes an optional C attribute, to search by a specific key or unique +constraint. For example: + + my $cd = $schema->resultset('CD')->find_or_create( + { + artist => 'Massive Attack', + title => 'Mezzanine', + }, + { key => 'artist_title' } + ); + +See also L and L. + +=cut + +sub find { + my ($self, @vals) = @_; + my $attrs = (@vals > 1 && ref $vals[$#vals] eq 'HASH' ? pop(@vals) : {}); + + my @cols = $self->{source}->primary_columns; + if (exists $attrs->{key}) { + my %uniq = $self->{source}->unique_constraints; + $self->( "Unknown key " . $attrs->{key} . " on " . $self->name ) + unless exists $uniq{$attrs->{key}}; + @cols = @{ $uniq{$attrs->{key}} }; + } + #use Data::Dumper; warn Dumper($attrs, @vals, @cols); + $self->{source}->result_class->throw( "Can't find unless a primary key or unique constraint is defined" ) + unless @cols; + + my $query; + if (ref $vals[0] eq 'HASH') { + $query = $vals[0]; + } elsif (@cols == @vals) { + $query = {}; + @{$query}{@cols} = @vals; + } else { + $query = {@vals}; + } + #warn Dumper($query); + # Useless -> disabled + #$self->{source}->result_class->throw( "Can't find unless all primary keys are specified" ) + # unless (keys %$query >= @pk); # If we check 'em we run afoul of uc/lc + # column names etc. Not sure what to do yet + return $self->search($query)->next; +} + +=head2 search_related + + $rs->search_related('relname', $cond?, $attrs?); + +Search the specified relationship. Optionally specify a condition for matching +records. + +=cut + +sub search_related { + my ($self, $rel, @rest) = @_; + my $rel_obj = $self->{source}->relationship_info($rel); + $self->{source}->result_class->throw( + "No such relationship ${rel} in search_related") + unless $rel_obj; + my $rs = $self->search(undef, { join => $rel }); + return $self->{source}->schema->resultset($rel_obj->{class} + )->search( undef, + { %{$rs->{attrs}}, + alias => $rel, + select => undef(), + as => undef() } + )->search(@rest); +} + =head2 cursor -Return a storage-driven cursor to the given resultset. +Returns a storage-driven cursor to the given resultset. =cut sub cursor { my ($self) = @_; - my ($db_class, $attrs) = @{$self}{qw/class attrs/}; - if ($attrs->{page}) { - $attrs->{rows} = $self->pager->entries_per_page; - $attrs->{offset} = $self->pager->skipped; - } + my ($source, $attrs) = @{$self}{qw/source attrs/}; + $attrs = { %$attrs }; return $self->{cursor} - ||= $db_class->storage->select($self->{from}, $self->{cols}, + ||= $source->storage->select($self->{from}, $attrs->{select}, $attrs->{where},$attrs); } +=head2 search_like + +Perform a search, but use C instead of equality as the condition. Note +that this is simply a convenience method; you most likely want to use +L with specific operators. + +For more information, see L. + +=cut + +sub search_like { + my $class = shift; + my $attrs = { }; + if (@_ > 1 && ref $_[$#_] eq 'HASH') { + $attrs = pop(@_); + } + my $query = ref $_[0] eq "HASH" ? { %{shift()} }: {@_}; + $query->{$_} = { 'like' => $query->{$_} } for keys %$query; + return $class->search($query, { %$attrs }); +} + =head2 slice($first, $last) Returns a subset of elements from the resultset. @@ -98,60 +293,48 @@ Returns a subset of elements from the resultset. sub slice { my ($self, $min, $max) = @_; my $attrs = { %{ $self->{attrs} || {} } }; - $self->{class}->throw("Can't slice without where") unless $attrs->{where}; - $attrs->{offset} = $min; + $attrs->{offset} ||= 0; + $attrs->{offset} += $min; $attrs->{rows} = ($max ? ($max - $min + 1) : 1); - my $slice = $self->new($self->{class}, $attrs); + my $slice = (ref $self)->new($self->{source}, $attrs); return (wantarray ? $slice->all : $slice); } -=head2 next +=head2 next -Returns the next element in the resultset (undef is there is none). +Returns the next element in the resultset (C is there is none). + +Can be used to efficiently iterate over records in the resultset: + + my $rs = $schema->resultset('CD')->search({}); + while (my $cd = $rs->next) { + print $cd->title; + } =cut sub next { my ($self) = @_; my @row = $self->cursor->next; +# warn Dumper(\@row); use Data::Dumper; return unless (@row); return $self->_construct_object(@row); } sub _construct_object { my ($self, @row) = @_; - my @cols = @{ $self->{attrs}{cols} }; - s/^me\.// for @cols; - @cols = grep { /\(/ or ! /\./ } @cols; - my $new; - unless ($self->{attrs}{prefetch}) { - $new = $self->{class}->_row_to_object(\@cols, \@row); - } else { - my @main = splice(@row, 0, scalar @cols); - $new = $self->{class}->_row_to_object(\@cols, \@main); - PRE: foreach my $pre (@{$self->{attrs}{prefetch}}) { - my $rel_obj = $self->{class}->_relationships->{$pre}; - my $pre_class = $self->{class}->resolve_class($rel_obj->{class}); - my @pre_cols = $pre_class->_select_columns; - my @vals = splice(@row, 0, scalar @pre_cols); - my $fetched = $pre_class->_row_to_object(\@pre_cols, \@vals); - $self->{class}->throw("No accessor for prefetched $pre") - unless defined $rel_obj->{attrs}{accessor}; - if ($rel_obj->{attrs}{accessor} eq 'single') { - foreach my $pri ($rel_obj->{class}->primary_columns) { - unless (defined $fetched->get_column($pri)) { - undef $fetched; - last; - } - } - $new->{_relationship_data}{$pre} = $fetched; - } elsif ($rel_obj->{attrs}{accessor} eq 'filter') { - $new->{_inflated_column}{$pre} = $fetched; - } else { - $self->{class}->throw("Don't know how to store prefetched $pre"); - } + my @cols = @{ $self->{attrs}{as} }; + #warn "@cols -> @row"; + my (%me, %pre); + foreach my $col (@cols) { + if ($col =~ /([^\.]+)\.([^\.]+)/) { + $pre{$1}[0]{$2} = shift @row; + } else { + $me{$col} = shift @row; } } + my $new = $self->{source}->result_class->inflate_result( + $self->{source}, \%me, \%pre); $new = $self->{attrs}{record_filter}->($new) if exists $self->{attrs}{record_filter}; return $new; @@ -160,29 +343,40 @@ sub _construct_object { =head2 count Performs an SQL C with the same query as the resultset was built -with to find the number of elements. +with to find the number of elements. If passed arguments, does a search +on the resultset and counts the results of that. =cut sub count { - my ($self) = @_; - my $db_class = $self->{class}; - my $attrs = { %{ $self->{attrs} } }; - unless ($self->{count}) { - # offset and order by are not needed to count - delete $attrs->{$_} for qw/offset order_by/; + my $self = shift; + return $self->search(@_)->count if @_ && defined $_[0]; + croak "Unable to ->count with a GROUP BY" if defined $self->{attrs}{group_by}; + unless (defined $self->{count}) { + my $attrs = { %{ $self->{attrs} }, + select => { 'count' => '*' }, + as => [ 'count' ] }; + # offset, order by and page are not needed to count. record_filter is cdbi + delete $attrs->{$_} for qw/rows offset order_by page pager record_filter/; - my @cols = 'COUNT(*)'; - $self->{count} = $db_class->storage->select_single($self->{from}, \@cols, - $self->{cond}, $attrs); + ($self->{count}) = (ref $self)->new($self->{source}, $attrs)->cursor->next; } return 0 unless $self->{count}; - return $self->{pager}->entries_on_this_page if ($self->{pager}); - return ( $attrs->{rows} && $attrs->{rows} < $self->{count} ) - ? $attrs->{rows} - : $self->{count}; + my $count = $self->{count}; + $count -= $self->{attrs}{offset} if $self->{attrs}{offset}; + $count = $self->{attrs}{rows} if + ($self->{attrs}{rows} && $self->{attrs}{rows} < $count); + return $count; } +=head2 count_literal + +Calls L with the passed arguments, then L. + +=cut + +sub count_literal { shift->search_literal(@_)->count; } + =head2 all Returns all elements in the resultset. Called implictly if the resultset @@ -218,36 +412,75 @@ sub first { return $_[0]->reset->next; } +=head2 update(\%values) + +Sets the specified columns in the resultset to the supplied values. + +=cut + +sub update { + my ($self, $values) = @_; + croak "Values for update must be a hash" unless ref $values eq 'HASH'; + return $self->{source}->storage->update( + $self->{source}->from, $values, $self->{cond}); +} + +=head2 update_all(\%values) + +Fetches all objects and updates them one at a time. Note that C +will run cascade triggers while L will not. + +=cut + +sub update_all { + my ($self, $values) = @_; + croak "Values for update must be a hash" unless ref $values eq 'HASH'; + foreach my $obj ($self->all) { + $obj->set_columns($values)->update; + } + return 1; +} + =head2 delete -Deletes all elements in the resultset. +Deletes the contents of the resultset from its result source. =cut sub delete { my ($self) = @_; - $_->delete for $self->all; + $self->{source}->storage->delete($self->{source}->from, $self->{cond}); return 1; } -*delete_all = \&delete; # Yeah, yeah, yeah ... +=head2 delete_all + +Fetches all objects and deletes them one at a time. Note that C +will run cascade triggers while L will not. + +=cut + +sub delete_all { + my ($self) = @_; + $_->delete for $self->all; + return 1; +} =head2 pager Returns a L object for the current resultset. Only makes -sense for queries with page turned on. +sense for queries with a C attribute. =cut sub pager { my ($self) = @_; my $attrs = $self->{attrs}; - delete $attrs->{offset}; - my $rows_per_page = delete $attrs->{rows} || 10; - $self->{pager} ||= Data::Page->new( - $self->count, $rows_per_page, $attrs->{page} || 1); - $attrs->{rows} = $rows_per_page; - return $self->{pager}; + croak "Can't create pager for non-paged rs" unless $self->{page}; + $attrs->{rows} ||= 10; + $self->count; + return $self->{pager} ||= Data::Page->new( + $self->{count}, $attrs->{rows}, $self->{page}); } =head2 page($page_num) @@ -258,52 +491,379 @@ Returns a new resultset for the specified page. sub page { my ($self, $page) = @_; - my $attrs = $self->{attrs}; + my $attrs = { %{$self->{attrs}} }; $attrs->{page} = $page; - return $self->new($self->{class}, $attrs); + return (ref $self)->new($self->{source}, $attrs); +} + +=head2 new_result(\%vals) + +Creates a result in the resultset's result class. + +=cut + +sub new_result { + my ($self, $values) = @_; + $self->{source}->result_class->throw( "new_result needs a hash" ) + unless (ref $values eq 'HASH'); + $self->{source}->result_class->throw( "Can't abstract implicit construct, condition not a hash" ) + if ($self->{cond} && !(ref $self->{cond} eq 'HASH')); + my %new = %$values; + my $alias = $self->{attrs}{alias}; + foreach my $key (keys %{$self->{cond}||{}}) { + $new{$1} = $self->{cond}{$key} if ($key =~ m/^(?:$alias\.)?([^\.]+)$/); + } + my $obj = $self->{source}->result_class->new(\%new); + $obj->result_source($self->{source}) if $obj->can('result_source'); + $obj; +} + +=head2 create(\%vals) + +Inserts a record into the resultset and returns the object. + +Effectively a shortcut for C<< ->new_result(\%vals)->insert >>. + +=cut + +sub create { + my ($self, $attrs) = @_; + $self->{source}->result_class->throw( "create needs a hashref" ) unless ref $attrs eq 'HASH'; + return $self->new_result($attrs)->insert; +} + +=head2 find_or_create(\%vals, \%attrs?) + + $class->find_or_create({ key => $val, ... }); + +Searches for a record matching the search condition; if it doesn't find one, +creates one and returns that instead. + + my $cd = $schema->resultset('CD')->find_or_create({ + cdid => 5, + artist => 'Massive Attack', + title => 'Mezzanine', + year => 2005, + }); + +Also takes an optional C attribute, to search by a specific key or unique +constraint. For example: + + my $cd = $schema->resultset('CD')->find_or_create( + { + artist => 'Massive Attack', + title => 'Mezzanine', + }, + { key => 'artist_title' } + ); + +See also L and L. + +=cut + +sub find_or_create { + my $self = shift; + my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {}); + my $hash = ref $_[0] eq "HASH" ? shift : {@_}; + my $exists = $self->find($hash, $attrs); + return defined($exists) ? $exists : $self->create($hash); +} + +=head2 update_or_create + + $class->update_or_create({ key => $val, ... }); + +First, search for an existing row matching one of the unique constraints +(including the primary key) on the source of this resultset. If a row is +found, update it with the other given column values. Otherwise, create a new +row. + +Takes an optional C attribute to search on a specific unique constraint. +For example: + + # In your application + my $cd = $schema->resultset('CD')->update_or_create( + { + artist => 'Massive Attack', + title => 'Mezzanine', + year => 1998, + }, + { key => 'artist_title' } + ); + +If no C is specified, it searches on all unique constraints defined on the +source, including the primary key. + +If the C is specified as C, search only on the primary key. + +See also L and L. + +=cut + +sub update_or_create { + my $self = shift; + + my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {}); + my $hash = ref $_[0] eq "HASH" ? shift : {@_}; + + my %unique_constraints = $self->{source}->unique_constraints; + my @constraint_names = (exists $attrs->{key} + ? ($attrs->{key}) + : keys %unique_constraints); + + my @unique_hashes; + foreach my $name (@constraint_names) { + my @unique_cols = @{ $unique_constraints{$name} }; + my %unique_hash = + map { $_ => $hash->{$_} } + grep { exists $hash->{$_} } + @unique_cols; + + push @unique_hashes, \%unique_hash + if (scalar keys %unique_hash == scalar @unique_cols); + } + + my $row; + if (@unique_hashes) { + $row = $self->search(\@unique_hashes, { rows => 1 })->first; + if ($row) { + $row->set_columns($hash); + $row->update; + } + } + + unless ($row) { + $row = $self->create($hash); + } + + return $row; } -=head1 Attributes +=head1 ATTRIBUTES -The resultset takes various attributes that modify its behavior. -Here's an overview of them: +The resultset takes various attributes that modify its behavior. Here's an +overview of them: =head2 order_by -Which column(s) to order the results by. This is currently passed -through directly to SQL, so you can give e.g. C for a -descending order. +Which column(s) to order the results by. This is currently passed through +directly to SQL, so you can give e.g. C for a descending order. -=head2 cols +=head2 cols (arrayref) -Which columns should be retrieved. +Shortcut to request a particular set of columns to be retrieved. Adds +C onto the start of any column without a C<.> in it and sets C as normal. -=head2 join +=head2 select (arrayref) + +Indicates which columns should be selected from the storage. You can use +column names, or in the case of RDBMS back ends, function or stored procedure +names: + + $rs = $schema->resultset('Foo')->search( + {}, + { + select => { + 'column_name', + { count => 'column_to_count' }, + { sum => 'column_to_sum' } + } + } + ); + +When you use function/stored procedure names and do not supply an C +attribute, the column names returned are storage-dependent. E.g. MySQL would +return a column named C in the above example. + +=head2 as (arrayref) + +Indicates column names for object inflation. This is used in conjunction with +C contains one or more function or stored +procedure names: + + $rs = $schema->resultset('Foo')->search( + {}, + { + select => { + 'column1', + { count => 'column2' } + }, + as => [qw/ column1 column2_count /] + } + ); + + my $foo = $rs->first(); # get the first Foo + +If the object against which the search is performed already has an accessor +matching a column name specified in C, the value can be retrieved using +the accessor as normal: + + my $column1 = $foo->column1(); + +If on the other hand an accessor does not exist in the object, you need to +use C instead: -Contains a list of relations that should be joined for this query. Can also -contain a hash reference to refer to that relation's relations. So, if one column -in your class C foo and another C bar, you can do -C<< join => [qw/ foo bar /] >> to join both (and e.g. use them for C). -If a foo contains many margles and you want to join those too, you can do -C<< join => { foo => 'margle' } >>. If you want to fetch the columns from the -related table as well, see C below. + my $column2_count = $foo->get_column('column2_count'); -=head2 from +You can create your own accessors if required - see +L for details. -This attribute can contain a arrayref of elements. Each element can be another -arrayref, to nest joins, or it can be a hash which represents the two sides -of the join. +=head2 join -NOTE: Use this on your own risk. This allows you to shoot your foot off! +Contains a list of relationships that should be joined for this query. For +example: + + # Get CDs by Nine Inch Nails + my $rs = $schema->resultset('CD')->search( + { 'artist.name' => 'Nine Inch Nails' }, + { join => 'artist' } + ); + +Can also contain a hash reference to refer to the other relation's relations. +For example: + + package MyApp::Schema::Track; + use base qw/DBIx::Class/; + __PACKAGE__->table('track'); + __PACKAGE__->add_columns(qw/trackid cd position title/); + __PACKAGE__->set_primary_key('trackid'); + __PACKAGE__->belongs_to(cd => 'MyApp::Schema::CD'); + 1; + + # In your application + my $rs = $schema->resultset('Artist')->search( + { 'track.title' => 'Teardrop' }, + { + join => { cd => 'track' }, + order_by => 'artist.name', + } + ); + +If you want to fetch the columns from the related table as well, see +C below. + +=head2 prefetch + +Contains a list of relationships that should be fetched along with the main +query (when they are accessed afterwards they will have already been +"prefetched"). This is useful for when you know you will need the related +objects, because it saves a query. Currently limited to prefetching +one relationship deep, so unlike C, prefetch must be an arrayref. + +=head2 from (arrayref) + +The C attribute gives you manual control over the C clause of SQL +statements generated by L, allowing you to express custom C +clauses. + +NOTE: Use this on your own risk. This allows you to shoot off your foot! +C will usually do what you need and it is strongly recommended that you +avoid using C unless you cannot achieve the desired result using C. + +In simple terms, C works as follows: + + [ + { => , -join-type => 'inner|left|right' } + [] # nested JOIN (optional) + { = } + ] + + JOIN +
+ [JOIN ...] + ON = + +An easy way to follow the examples below is to remember the following: + + Anything inside "[]" is a JOIN + Anything inside "{}" is a condition for the enclosing JOIN + +The following examples utilize a "person" table in a family tree application. +In order to express parent->child relationships, this table is self-joined: + + # Person->belongs_to('father' => 'Person'); + # Person->belongs_to('mother' => 'Person'); + +C can be used to nest joins. Here we return all children with a father, +then search against all mothers of those children: + + $rs = $schema->resultset('Person')->search( + {}, + { + alias => 'mother', # alias columns in accordance with "from" + from => [ + { mother => 'person' }, + [ + [ + { child => 'person' }, + [ + { father => 'person' }, + { 'father.person_id' => 'child.father_id' } + ] + ], + { 'mother.person_id' => 'child.mother_id' } + ], + ] + }, + ); + + # Equivalent SQL: + # SELECT mother.* FROM person mother + # JOIN ( + # person child + # JOIN person father + # ON ( father.person_id = child.father_id ) + # ) + # ON ( mother.person_id = child.mother_id ) + +The type of any join can be controlled manually. To search against only people +with a father in the person table, we could explicitly use C: + + $rs = $schema->resultset('Person')->search( + {}, + { + alias => 'child', # alias columns in accordance with "from" + from => [ + { child => 'person' }, + [ + { father => 'person', -join-type => 'inner' }, + { 'father.id' => 'child.father_id' } + ], + ] + }, + ); + + # Equivalent SQL: + # SELECT child.* FROM person child + # INNER JOIN person father ON child.father_id = father.id =head2 page -For a paged resultset, specifies which page to retrieve. Leave unset +For a paged resultset, specifies which page to retrieve. Leave unset for an unpaged resultset. =head2 rows -For a paged resultset, how many rows per page +For a paged resultset, how many rows per page: + + rows => 10 + +Can also be used to simulate an SQL C. + +=head2 group_by (arrayref) + +A arrayref of columns to group by. Can include columns of joined tables. Note +note that L doesn't work on grouped resultsets. + + group_by => [qw/ column1 column2 ... /] + +=head2 distinct + +Set to 1 to group by all columns. + +For more examples of using these attributes, see +L. =cut