X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FResultSetColumn.pm;h=12623a3370da64817648cf2ea1c3a1af129d48cd;hb=37aafa2ede65e38af8fe9eda374ad4626290932f;hp=f27259297dc2ac0f3507cfe763332738493b9fdd;hpb=658fa250be6ed1944d042ccf985d5c05d41111f6;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/ResultSetColumn.pm b/lib/DBIx/Class/ResultSetColumn.pm index f272592..12623a3 100644 --- a/lib/DBIx/Class/ResultSetColumn.pm +++ b/lib/DBIx/Class/ResultSetColumn.pm @@ -1,8 +1,13 @@ package DBIx::Class::ResultSetColumn; + use strict; use warnings; + use base 'DBIx::Class'; -use List::Util; + +use Carp::Clan qw/^DBIx::Class/; +use DBIx::Class::Exception; +use List::Util (); =head1 NAME @@ -36,21 +41,79 @@ passed as params. Used internally by L. sub new { my ($class, $rs, $column) = @_; $class = ref $class if ref $class; - my $new_parent_rs = $rs->search_rs; # we don't want to mess up the original, so clone it - my $attrs = $new_parent_rs->_resolved_attrs; - $new_parent_rs->{attrs}->{$_} = undef for qw(prefetch include_columns +select +as); # prefetch, include_columns, +select, +as cause additional columns to be fetched + + $rs->throw_exception('column must be supplied') unless $column; + + my $orig_attrs = $rs->_resolved_attrs; + my $alias = $rs->current_source_alias; # If $column can be found in the 'as' list of the parent resultset, use the # corresponding element of its 'select' list (to keep any custom column # definition set up with 'select' or '+select' attrs), otherwise use $column # (to create a new column definition on-the-fly). - my $as_list = $attrs->{as} || []; - my $select_list = $attrs->{select} || []; + my $as_list = $orig_attrs->{as} || []; + my $select_list = $orig_attrs->{select} || []; my $as_index = List::Util::first { ($as_list->[$_] || "") eq $column } 0..$#$as_list; my $select = defined $as_index ? $select_list->[$as_index] : $column; + my $new_parent_rs; + # analyze the order_by, and see if it is done over a function/nonexistentcolumn + # if this is the case we will need to wrap a subquery since the result of RSC + # *must* be a single column select + my %collist = map + { $_ => 1, ($_ =~ /\./) ? () : ( "$alias.$_" => 1 ) } + ($rs->result_source->columns, $column) + ; + if ( + scalar grep + { ! $collist{$_} } + ( $rs->result_source->schema->storage->_extract_order_columns ($orig_attrs->{order_by} ) ) + ) { + # nuke the prefetch before collapsing to sql + my $subq_rs = $rs->search; + $subq_rs->{attrs}{join} = $subq_rs->_merge_joinpref_attr( $subq_rs->{attrs}{join}, delete $subq_rs->{attrs}{prefetch} ); + $new_parent_rs = $subq_rs->as_subselect_rs; + } + + $new_parent_rs ||= $rs->search_rs; + my $new_attrs = $new_parent_rs->{attrs} ||= {}; + + # prefetch causes additional columns to be fetched, but we can not just make a new + # rs via the _resolved_attrs trick - we need to retain the separation between + # +select/+as and select/as. At the same time we want to preserve any joins that the + # prefetch would otherwise generate. + $new_attrs->{join} = $rs->_merge_joinpref_attr( $new_attrs->{join}, delete $new_attrs->{prefetch} ); + + # {collapse} would mean a has_many join was injected, which in turn means + # we need to group *IF WE CAN* (only if the column in question is unique) + if (!$orig_attrs->{group_by} && keys %{$orig_attrs->{collapse}}) { + + # scan for a constraint that would contain our column only - that'd be proof + # enough it is unique + my $constraints = { $rs->result_source->unique_constraints }; + for my $constraint_columns ( values %$constraints ) { + + next unless @$constraint_columns == 1; + + my $col = $constraint_columns->[0]; + my $fqcol = join ('.', $new_attrs->{alias}, $col); + + if ($col eq $select or $fqcol eq $select) { + $new_attrs->{group_by} = [ $select ]; + delete $new_attrs->{distinct}; # it is ignored when group_by is present + last; + } + } + + if (!$new_attrs->{group_by}) { + carp ( + "Attempting to retrieve non-unique column '$column' on a resultset containing " + . 'one-to-many joins will return duplicate results.' + ); + } + } + my $new = bless { _select => $select, _as => $column, _parent_resultset => $new_parent_rs }, $class; - $new->throw_exception("column must be supplied") unless $column; return $new; } @@ -60,15 +123,17 @@ sub new { =item Arguments: none -=item Return Value: [ $sql, @bind ] +=item Return Value: \[ $sql, @bind ] =back Returns the SQL query and bind vars associated with the invocant. +This is generally used as the RHS for a subquery. + =cut -sub as_query { return shift->_resultset->as_query } +sub as_query { return shift->_resultset->as_query(@_) } =head2 next @@ -90,7 +155,10 @@ one value. sub next { my $self = shift; + + # using cursor so we don't inflate anything my ($row) = $self->_resultset->cursor->next; + return $row; } @@ -114,6 +182,8 @@ than row objects. sub all { my $self = shift; + + # using cursor so we don't inflate anything return map { $_->[0] } $self->_resultset->cursor->all; } @@ -159,7 +229,38 @@ Much like L but just returning the one value. sub first { my $self = shift; - my ($row) = $self->_resultset->cursor->reset->next; + + # using cursor so we don't inflate anything + $self->_resultset->cursor->reset; + my ($row) = $self->_resultset->cursor->next; + + return $row; +} + +=head2 single + +=over 4 + +=item Arguments: none + +=item Return Value: $value + +=back + +Much like L fetches one and only one column +value using the cursor directly. If additional rows are present a warning +is issued before discarding the cursor. + +=cut + +sub single { + my $self = shift; + + my $attrs = $self->_resultset->_resolved_attrs; + my ($row) = $self->_resultset->result_source->storage->select_single( + $attrs->{from}, $attrs->{select}, $attrs->{where}, $attrs + ); + return $row; } @@ -184,6 +285,24 @@ sub min { return shift->func('MIN'); } +=head2 min_rs + +=over 4 + +=item Arguments: none + +=item Return Value: $resultset + +=back + + my $rs = $year_col->min_rs(); + +Wrapper for ->func_rs for function MIN(). + +=cut + +sub min_rs { return shift->func_rs('MIN') } + =head2 max =over 4 @@ -205,6 +324,24 @@ sub max { return shift->func('MAX'); } +=head2 max_rs + +=over 4 + +=item Arguments: none + +=item Return Value: $resultset + +=back + + my $rs = $year_col->max_rs(); + +Wrapper for ->func_rs for function MAX(). + +=cut + +sub max_rs { return shift->func_rs('MAX') } + =head2 sum =over 4 @@ -226,6 +363,24 @@ sub sum { return shift->func('SUM'); } +=head2 sum_rs + +=over 4 + +=item Arguments: none + +=item Return Value: $resultset + +=back + + my $rs = $year_col->sum_rs(); + +Wrapper for ->func_rs for function SUM(). + +=cut + +sub sum_rs { return shift->func_rs('SUM') } + =head2 func =over 4 @@ -248,8 +403,8 @@ value. Produces the following SQL: sub func { my ($self,$function) = @_; - my $cursor = $self->{_parent_resultset}->search(undef, {select => {$function => $self->{_select}}, as => [$self->{_as}]})->cursor; - + my $cursor = $self->func_rs($function)->cursor; + if( wantarray ) { return map { $_->[ 0 ] } $cursor->all; } @@ -257,18 +412,44 @@ sub func { return ( $cursor->next )[ 0 ]; } +=head2 func_rs + +=over 4 + +=item Arguments: $function + +=item Return Value: $resultset + +=back + +Creates the resultset that C uses to run its query. + +=cut + +sub func_rs { + my ($self,$function) = @_; + return $self->{_parent_resultset}->search( + undef, { + select => {$function => $self->{_select}}, + as => [$self->{_as}], + }, + ); +} + =head2 throw_exception See L for details. - + =cut - + sub throw_exception { my $self=shift; + if (ref $self && $self->{_parent_resultset}) { - $self->{_parent_resultset}->throw_exception(@_) - } else { - croak(@_); + $self->{_parent_resultset}->throw_exception(@_); + } + else { + DBIx::Class::Exception->throw(@_); } } @@ -282,7 +463,7 @@ sub throw_exception { # # Returns the underlying resultset. Creates it from the parent resultset if # necessary. -# +# sub _resultset { my $self = shift;