use warnings;
use overload
'0+' => 'count',
+ 'bool' => sub { 1; },
fallback => 1;
use Data::Page;
use Storable;
+use base qw/DBIx::Class/;
+__PACKAGE__->load_components(qw/AccessorGroup/);
+__PACKAGE__->mk_group_accessors('simple' => 'result_source');
+
=head1 NAME
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 = $schema->resultset('Foo')->search(bar => 'baz');
=head1 DESCRIPTION
The resultset is also known as an iterator. It is responsible for handling
-queries that may return an arbitrary number of rows, e.g. via C<search>
+queries that may return an arbitrary number of rows, e.g. via L</search>
or a C<has_many> relationship.
+In the examples below, the following table classes are used:
+
+ package MyApp::Schema::Artist;
+ use base qw/DBIx::Class/;
+ __PACKAGE__->table('artist');
+ __PACKAGE__->add_columns(qw/artistid name/);
+ __PACKAGE__->set_primary_key('artistid');
+ __PACKAGE__->has_many(cds => 'MyApp::Schema::CD');
+ 1;
+
+ package MyApp::Schema::CD;
+ use base qw/DBIx::Class/;
+ __PACKAGE__->table('artist');
+ __PACKAGE__->add_columns(qw/cdid artist title year/);
+ __PACKAGE__->set_primary_key('cdid');
+ __PACKAGE__->belongs_to(artist => 'MyApp::Schema::Artist');
+ 1;
+
=head1 METHODS
=head2 new($source, \%$attrs)
-The resultset constructor. Takes a source object (usually a DBIx::Class::Table)
-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<DBIx::Class::ResultSourceProxy::Table>) and an attribute hash (see L</ATRRIBUTES>
+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</search> called in scalar context:
+
+ my $rs = $schema->resultset('CD')->search({ title => '100th Window' });
=cut
my $class = shift;
return $class->new_result(@_) if ref $class;
my ($source, $attrs) = @_;
- #use Data::Dumper; warn Dumper(@_);
+ #use Data::Dumper; warn Dumper($attrs);
$attrs = Storable::dclone($attrs || {}); # { %{ $attrs || {} } };
my %seen;
my $alias = ($attrs->{alias} ||= 'me');
- if (!$attrs->{select}) {
+ if ($attrs->{cols} || !$attrs->{select}) {
+ delete $attrs->{as} if $attrs->{cols};
my @cols = ($attrs->{cols}
? @{delete $attrs->{cols}}
- : $source->result_class->_select_columns);
+ : $source->columns);
$attrs->{select} = [ map { m/\./ ? $_ : "${alias}.$_" } @cols ];
}
$attrs->{as} ||= [ map { m/^$alias\.(.*)$/ ? $1 : $_ } @{$attrs->{select}} ];
+ if (my $include = delete $attrs->{include_columns}) {
+ push(@{$attrs->{select}}, @$include);
+ push(@{$attrs->{as}}, map { m/([^\.]+)$/; $1; } @$include);
+ }
#use Data::Dumper; warn Dumper(@{$attrs}{qw/select as/});
$attrs->{from} ||= [ { $alias => $source->from } ];
+ $attrs->{seen_join} ||= {};
if (my $join = delete $attrs->{join}) {
foreach my $j (ref $join eq 'ARRAY'
? (@{$join}) : ($join)) {
$seen{$j} = 1;
}
}
- push(@{$attrs->{from}}, $source->resolve_join($join, $attrs->{alias}));
+ push(@{$attrs->{from}}, $source->resolve_join($join, $attrs->{alias}, $attrs->{seen_join}));
}
$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};
- my @pre =
- map { "$pre.$_" }
- $source->related_source($pre)->columns;
- push(@{$attrs->{select}}, @pre);
- push(@{$attrs->{as}}, @pre);
+
+ if (my $prefetch = delete $attrs->{prefetch}) {
+ foreach my $p (ref $prefetch eq 'ARRAY'
+ ? (@{$prefetch}) : ($prefetch)) {
+ if( ref $p eq 'HASH' ) {
+ foreach my $key (keys %$p) {
+ push(@{$attrs->{from}}, $source->resolve_join($p, $attrs->{alias}))
+ unless $seen{$key};
+ }
+ }
+ else {
+ push(@{$attrs->{from}}, $source->resolve_join($p, $attrs->{alias}))
+ unless $seen{$p};
+ }
+ my @prefetch = $source->resolve_prefetch($p, $attrs->{alias});
+ #die Dumper \@cols;
+ push(@{$attrs->{select}}, map { $_->[0] } @prefetch);
+ push(@{$attrs->{as}}, map { $_->[1] } @prefetch);
+ }
}
+
if ($attrs->{page}) {
$attrs->{rows} ||= 10;
$attrs->{offset} ||= 0;
$attrs->{offset} += ($attrs->{rows} * ($attrs->{page} - 1));
}
my $new = {
- source => $source,
+ result_source => $source,
cond => $attrs->{where},
from => $attrs->{from},
count => undef,
=head2 search
- my @obj = $rs->search({ foo => 3 }); # "... WHERE foo = 3"
- my $new_rs = $rs->search({ foo => 3 });
-
+ 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 ->search(undef, \%attrs);
-
- my @all = $class->search({}, { cols => [qw/foo bar/] }); # "SELECT foo, bar FROM $class_table"
+call it as C<search({}, \%attrs);>.
+
+ # "SELECT foo, bar FROM $class_table"
+ my @all = $class->search({}, { cols => [qw/foo bar/] });
=cut
$attrs->{where} = $where;
}
- my $rs = (ref $self)->new($self->{source}, $attrs);
+ my $rs = (ref $self)->new($self->result_source, $attrs);
return (wantarray ? $rs->all : $rs);
}
-=head2 search_literal
+=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
+resultset.
=cut
return $self->search(\$cond, $attrs);
}
-=head2 find(@colvalues), find(\%cols)
+=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);
-Finds a row based on its primary key(s).
+Also takes an optional C<key> attribute, to search by a specific key or unique
+constraint. For example:
-=cut
+ my $cd = $schema->resultset('CD')->find_or_create(
+ {
+ artist => 'Massive Attack',
+ title => 'Mezzanine',
+ },
+ { key => 'artist_title' }
+ );
+
+See also L</find_or_create> and L</update_or_create>.
+
+=cut
sub find {
my ($self, @vals) = @_;
my $attrs = (@vals > 1 && ref $vals[$#vals] eq 'HASH' ? pop(@vals) : {});
- my @pk = $self->{source}->primary_columns;
- #use Data::Dumper; warn Dumper($attrs, @vals, @pk);
- $self->{source}->result_class->throw( "Can't find unless primary columns are defined" )
- unless @pk;
+
+ my @cols = $self->result_source->primary_columns;
+ if (exists $attrs->{key}) {
+ my %uniq = $self->result_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->throw_exception( "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 (@pk == @vals) {
+ $query = { %{$vals[0]} };
+ } elsif (@cols == @vals) {
$query = {};
- @{$query}{@pk} = @vals;
+ @{$query}{@cols} = @vals;
} else {
$query = {@vals};
}
+ foreach (keys %$query) {
+ next if m/\./;
+ $query->{$self->{attrs}{alias}.'.'.$_} = delete $query->{$_};
+ }
#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;
+ return $self->search($query,$attrs)->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(
+ my $rel_obj = $self->result_source->relationship_info($rel);
+ $self->throw_exception(
"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}
+ my $alias = ($rs->{attrs}{seen_join}{$rel} > 1
+ ? join('_', $rel, $rs->{attrs}{seen_join}{$rel})
+ : $rel);
+ return $self->result_source->schema->resultset($rel_obj->{class}
)->search( undef,
{ %{$rs->{attrs}},
- alias => $rel,
+ alias => $alias,
select => undef(),
as => undef() }
)->search(@rest);
sub cursor {
my ($self) = @_;
- my ($source, $attrs) = @{$self}{qw/source attrs/};
+ my ($attrs) = $self->{attrs};
$attrs = { %$attrs };
return $self->{cursor}
- ||= $source->storage->select($self->{from}, $attrs->{select},
+ ||= $self->result_source->storage->select($self->{from}, $attrs->{select},
$attrs->{where},$attrs);
}
-=head2 search_like
-
-Identical to search except defaults to 'LIKE' instead of '=' in condition
-
-=cut
+=head2 search_like
+
+Perform a search, but use C<LIKE> instead of equality as the condition. Note
+that this is simply a convenience method; you most likely want to use
+L</search> with specific operators.
+
+For more information, see L<DBIx::Class::Manual::Cookbook>.
+
+=cut
sub search_like {
my $class = shift;
$attrs->{offset} ||= 0;
$attrs->{offset} += $min;
$attrs->{rows} = ($max ? ($max - $min + 1) : 1);
- my $slice = (ref $self)->new($self->{source}, $attrs);
+ my $slice = (ref $self)->new($self->result_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<undef> 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}{as} };
+ my @as = @{ $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 $info = [ {}, {} ];
+ foreach my $as (@as) {
+ my $target = $info;
+ my @parts = split(/\./, $as);
+ my $col = pop(@parts);
+ foreach my $p (@parts) {
+ $target = $target->[1]->{$p} ||= [];
}
+ $target->[0]->{$col} = shift @row;
}
- my $new = $self->{source}->result_class->inflate_result(\%me, \%pre);
+ #use Data::Dumper; warn Dumper(\@as, $info);
+ my $new = $self->result_source->result_class->inflate_result(
+ $self->result_source, @$info);
$new = $self->{attrs}{record_filter}->($new)
if exists $self->{attrs}{record_filter};
return $new;
}
+=head2 result_source
+
+Returns a reference to the result source for this recordset.
+
+=cut
+
+
=head2 count
Performs an SQL C<COUNT> with the same query as the resultset was built
with to find the number of elements. If passed arguments, does a search
on the resultset and counts the results of that.
+Note: When using C<count> with C<group_by>, L<DBIX::Class> emulates C<GROUP BY>
+using C<COUNT( DISTINCT( columns ) )>. Some databases (notably SQLite) do
+not support C<DISTINCT> with multiple columns. If you are using such a
+database, you should only use columns from the main table in your C<group_by>
+clause.
+
=cut
sub count {
my $self = shift;
return $self->search(@_)->count if @_ && defined $_[0];
- die "Unable to ->count with a GROUP BY" if defined $self->{attrs}{group_by};
unless (defined $self->{count}) {
+ my $group_by;
+ my $select = { 'count' => '*' };
+ if( $group_by = delete $self->{attrs}{group_by} ) {
+ my @distinct = (ref $group_by ? @$group_by : ($group_by));
+ # todo: try CONCAT for multi-column pk
+ my @pk = $self->result_source->primary_columns;
+ if( scalar(@pk) == 1 ) {
+ my $pk = shift(@pk);
+ my $alias = $self->{attrs}{alias};
+ my $re = qr/^($alias\.)?$pk$/;
+ foreach my $column ( @$group_by ) {
+ if( $column =~ $re ) {
+ @distinct = ( $column );
+ last;
+ }
+ }
+ }
+
+ $select = { count => { 'distinct' => \@distinct } };
+ #use Data::Dumper; die Dumper $select;
+ }
+
my $attrs = { %{ $self->{attrs} },
- select => { 'count' => '*' },
+ select => $select,
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/;
- ($self->{count}) = (ref $self)->new($self->{source}, $attrs)->cursor->next;
+ ($self->{count}) = (ref $self)->new($self->result_source, $attrs)->cursor->next;
+ $self->{attrs}{group_by} = $group_by;
}
return 0 unless $self->{count};
my $count = $self->{count};
=head2 count_literal
-Calls search_literal with the passed arguments, then count.
+Calls L</search_literal> with the passed arguments, then L</count>.
=cut
return $_[0]->reset->next;
}
+=head2 update(\%values)
+
+Sets the specified columns in the resultset to the supplied values.
+
+=cut
+
+sub update {
+ my ($self, $values) = @_;
+ $self->throw_exception("Values for update must be a hash") unless ref $values eq 'HASH';
+ return $self->result_source->storage->update(
+ $self->result_source->from, $values, $self->{cond});
+}
+
+=head2 update_all(\%values)
+
+Fetches all objects and updates them one at a time. Note that C<update_all>
+will run cascade triggers while L</update> will not.
+
+=cut
+
+sub update_all {
+ my ($self, $values) = @_;
+ $self->throw_exception("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;
+ my $del = {};
+ $self->throw_exception("Can't delete on resultset with condition unless hash or array")
+ unless (ref($self->{cond}) eq 'HASH' || ref($self->{cond}) eq 'ARRAY');
+ if (ref $self->{cond} eq 'ARRAY') {
+ $del = [ map { my %hash;
+ foreach my $key (keys %{$_}) {
+ $key =~ /([^\.]+)$/;
+ $hash{$1} = $_->{$key};
+ }; \%hash; } @{$self->{cond}} ];
+ } elsif ((keys %{$self->{cond}})[0] eq '-and') {
+ $del->{-and} = [ map { my %hash;
+ foreach my $key (keys %{$_}) {
+ $key =~ /([^\.]+)$/;
+ $hash{$1} = $_->{$key};
+ }; \%hash; } @{$self->{cond}{-and}} ];
+ } else {
+ foreach my $key (keys %{$self->{cond}}) {
+ $key =~ /([^\.]+)$/;
+ $del->{$1} = $self->{cond}{$key};
+ }
+ }
+ $self->result_source->storage->delete($self->result_source->from, $del);
return 1;
}
-*delete_all = \&delete; # Yeah, yeah, yeah ...
+=head2 delete_all
+
+Fetches all objects and deletes them one at a time. Note that C<delete_all>
+will run cascade triggers while L</delete> will not.
+
+=cut
+
+sub delete_all {
+ my ($self) = @_;
+ $_->delete for $self->all;
+ return 1;
+}
=head2 pager
Returns a L<Data::Page> object for the current resultset. Only makes
-sense for queries with page turned on.
+sense for queries with a C<page> attribute.
=cut
sub pager {
my ($self) = @_;
my $attrs = $self->{attrs};
- die "Can't create pager for non-paged rs" unless $self->{page};
+ $self->throw_exception("Can't create pager for non-paged rs") unless $self->{page};
$attrs->{rows} ||= 10;
$self->count;
return $self->{pager} ||= Data::Page->new(
my ($self, $page) = @_;
my $attrs = { %{$self->{attrs}} };
$attrs->{page} = $page;
- return (ref $self)->new($self->{source}, $attrs);
+ return (ref $self)->new($self->result_source, $attrs);
}
=head2 new_result(\%vals)
-Creates a result in the resultset's result class
+Creates a result in the resultset's result class.
=cut
sub new_result {
my ($self, $values) = @_;
- $self->{source}->result_class->throw( "new_result needs a hash" )
+ $self->throw_exception( "new_result needs a hash" )
unless (ref $values eq 'HASH');
- $self->{source}->result_class->throw( "Can't abstract implicit construct, condition not a hash" )
+ $self->throw_exception( "Can't abstract implicit construct, condition not a hash" )
if ($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\.)?([^\.]+)$/);
}
- return $self->{source}->result_class->new(\%new);
+ my $obj = $self->result_source->result_class->new(\%new);
+ $obj->result_source($self->result_source) if $obj->can('result_source');
+ $obj;
}
=head2 create(\%vals)
-Inserts a record into the resultset and returns the object
+Inserts a record into the resultset and returns the object.
-Effectively a shortcut for ->new_result(\%vals)->insert
+Effectively a shortcut for C<< ->new_result(\%vals)->insert >>.
=cut
sub create {
my ($self, $attrs) = @_;
- $self->{source}->result_class->throw( "create needs a hashref" ) unless ref $attrs eq 'HASH';
+ $self->throw_exception( "create needs a hashref" ) unless ref $attrs eq 'HASH';
return $self->new_result($attrs)->insert;
}
-=head2 find_or_create(\%vals)
+=head2 find_or_create(\%vals, \%attrs?)
+
+ $class->find_or_create({ key => $val, ... });
- $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.
-
+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<key> 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</find> and L</update_or_create>.
+
=cut
sub find_or_create {
my $self = shift;
- my $hash = ref $_[0] eq "HASH" ? shift: {@_};
- my $exists = $self->find($hash);
+ 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<key> 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<key> is specified, it searches on all unique constraints defined on the
+source, including the primary key.
+
+If the C<key> is specified as C<primary>, search only on the primary key.
+
+See also L</find> and L</find_or_create>.
+
+=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->result_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;
+}
+
+=head2 throw_exception
+
+See Schema's throw_exception
+
+=cut
+
+sub throw_exception {
+ my $self=shift;
+ $self->result_source->schema->throw_exception(@_);
+}
+
=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<foo DESC> 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<foo DESC> for a descending order.
=head2 cols (arrayref)
-Shortcut to request a particular set of columns to be retrieved - adds
-'me.' onto the start of any column without a '.' in it and sets 'select'
-from that, then auto-populates 'as' from 'select' as normal
+Shortcut to request a particular set of columns to be retrieved. Adds
+C<me.> onto the start of any column without a C<.> in it and sets C<select>
+from that, then auto-populates C<as> from C<select> as normal.
+
+=head2 include_columns (arrayref)
+
+Shortcut to include additional columns in the returned results - for example
+
+ { include_columns => ['foo.name'], join => ['foo'] }
+
+would add a 'name' column to the information passed to object inflation
=head2 select (arrayref)
-Indicates which columns should be selected from the storage
+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<as>
+attribute, the column names returned are storage-dependent. E.g. MySQL would
+return a column named C<count(column_to_count)> in the above example.
=head2 as (arrayref)
-Indicates column names for object inflation
+Indicates column names for object inflation. This is used in conjunction with
+C<select>, usually when C<select> 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<as>, 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<get_column> instead:
+
+ my $column2_count = $foo->get_column('column2_count');
+
+You can create your own accessors if required - see
+L<DBIx::Class::Manual::Cookbook> for details.
=head2 join
-Contains a list of relationships 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<belongs_to> foo and another C<belongs_to> bar, you can do
-C<< join => [qw/ foo bar /] >> to join both (and e.g. use them for C<order_by>).
-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<prefetch> below.
+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',
+ }
+ );
-=head2 prefetch
+If the same join is supplied twice, it will be aliased to <rel>_2 (and
+similarly for a third time). For e.g.
-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
-object(s), because it saves a query. Currently limited to prefetching
-one relationship deep, so unlike C<join>, prefetch must be an arrayref.
+ my $rs = $schema->resultset('Artist')->search(
+ { 'cds.title' => 'Foo',
+ 'cds_2.title' => 'Bar' },
+ { join => [ qw/cds cds/ ] });
-=head2 from
+will return a set of all artists that have both a cd with title Foo and a cd
+with title Bar.
-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.
+If you want to fetch related objects from other tables as well, see C<prefetch>
+below.
-NOTE: Use this on your own risk. This allows you to shoot your foot off!
+=head2 prefetch arrayref/hashref
+
+Contains one or more 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 at least one query:
+
+ my $rs = $schema->resultset('Tag')->search(
+ {},
+ {
+ prefetch => {
+ cd => 'artist'
+ }
+ }
+ );
+
+The initial search results in SQL like the following:
+
+ SELECT tag.*, cd.*, artist.* FROM tag
+ JOIN cd ON tag.cd = cd.cdid
+ JOIN artist ON cd.artist = artist.artistid
+
+L<DBIx::Class> has no need to go back to the database when we access the
+C<cd> or C<artist> relationships, which saves us two SQL statements in this
+case.
+
+Simple prefetches will be joined automatically, so there is no need
+for a C<join> attribute in the above search. If you're prefetching to
+depth (e.g. { cd => { artist => 'label' } or similar), you'll need to
+specify the join as well.
+
+C<prefetch> can be used with the following relationship types: C<belongs_to>,
+C<has_one> (or if you're using C<add_relationship>, any relationship declared
+with an accessor type of 'single' or 'filter').
+
+=head2 from (arrayref)
+
+The C<from> attribute gives you manual control over the C<FROM> clause of SQL
+statements generated by L<DBIx::Class>, allowing you to express custom C<JOIN>
+clauses.
+
+NOTE: Use this on your own risk. This allows you to shoot off your foot!
+C<join> will usually do what you need and it is strongly recommended that you
+avoid using C<from> unless you cannot achieve the desired result using C<join>.
+
+In simple terms, C<from> works as follows:
+
+ [
+ { <alias> => <table>, -join-type => 'inner|left|right' }
+ [] # nested JOIN (optional)
+ { <table.column> = <foreign_table.foreign_key> }
+ ]
+
+ JOIN
+ <alias> <table>
+ [JOIN ...]
+ ON <table.column> = <foreign_table.foreign_key>
+
+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<from> 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<INNER JOIN>:
+
+ $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:
-=head2 group_by
+ rows => 10
-A list of columns to group by (note that 'count' doesn't work on grouped
-resultsets)
+Can also be used to simulate an SQL C<LIMIT>.
+
+=head2 group_by (arrayref)
+
+A arrayref of columns to group by. Can include columns of joined tables.
+
+ group_by => [qw/ column1 column2 ... /]
=head2 distinct
-Set to 1 to group by all columns
+Set to 1 to group by all columns.
+
+For more examples of using these attributes, see
+L<DBIx::Class::Manual::Cookbook>.
=cut
projects / dbsrgits/DBIx-Class.git / blobdiff