1 package #hide from PAUSE
2 DBIx::Class::Storage::DBIHacks;
5 # This module contains code that should never have seen the light of day,
6 # does not belong in the Storage, or is otherwise unfit for public
7 # display. The arrival of SQLA2 should immediately oboslete 90% of this
13 use base 'DBIx::Class::Storage';
16 use Carp::Clan qw/^DBIx::Class/;
19 # This is the code producing joined subqueries like:
20 # SELECT me.*, other.* FROM ( SELECT me.* FROM ... ) JOIN other ON ...
22 sub _adjust_select_args_for_complex_prefetch {
23 my ($self, $from, $select, $where, $attrs) = @_;
25 $self->throw_exception ('Nothing to prefetch... how did we get here?!')
26 if not @{$attrs->{_prefetch_select}};
28 $self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute')
29 if (ref $from ne 'ARRAY' || ref $from->[0] ne 'HASH' || ref $from->[1] ne 'ARRAY');
32 # generate inner/outer attribute lists, remove stuff that doesn't apply
33 my $outer_attrs = { %$attrs };
34 delete $outer_attrs->{$_} for qw/where bind rows offset group_by having/;
36 my $inner_attrs = { %$attrs };
37 delete $inner_attrs->{$_} for qw/for collapse _prefetch_select _collapse_order_by select as/;
40 # bring over all non-collapse-induced order_by into the inner query (if any)
41 # the outer one will have to keep them all
42 delete $inner_attrs->{order_by};
43 if (my $ord_cnt = @{$outer_attrs->{order_by}} - @{$outer_attrs->{_collapse_order_by}} ) {
44 $inner_attrs->{order_by} = [
45 @{$outer_attrs->{order_by}}[ 0 .. $ord_cnt - 1]
50 # generate the inner/outer select lists
51 # for inside we consider only stuff *not* brought in by the prefetch
52 # on the outside we substitute any function for its alias
53 my $outer_select = [ @$select ];
54 my $inner_select = [];
55 for my $i (0 .. ( @$outer_select - @{$outer_attrs->{_prefetch_select}} - 1) ) {
56 my $sel = $outer_select->[$i];
58 if (ref $sel eq 'HASH' ) {
59 $sel->{-as} ||= $attrs->{as}[$i];
60 $outer_select->[$i] = join ('.', $attrs->{alias}, ($sel->{-as} || "inner_column_$i") );
63 push @$inner_select, $sel;
66 # normalize a copy of $from, so it will be easier to work with further
67 # down (i.e. promote the initial hashref to an AoH)
69 $from->[0] = [ $from->[0] ];
71 my ( $restrict_aliases, $select_aliases, $prefetch_aliases ) =
72 $self->_choose_aliases_to_include( $from, $where, $inner_select, $inner_attrs, $outer_select,
76 # construct the inner $from for the subquery
77 my %inner_joins = (map { %{$_ || {}} } ($restrict_aliases, $select_aliases) );
80 push @inner_from, $j if $inner_joins{$j->[0]{-alias}};
83 # if a multi-type join was needed in the subquery ("multi" is indicated by
84 # presence in {collapse}) - add a group_by to simulate the collapse in the subq
85 unless ($inner_attrs->{group_by}) {
86 for my $alias (keys %inner_joins) {
88 # the dot comes from some weirdness in collapse
89 # remove after the rewrite
90 if ($attrs->{collapse}{".$alias"}) {
91 $inner_attrs->{group_by} ||= $inner_select;
97 # demote the inner_from head
98 $inner_from[0] = $inner_from[0][0];
100 # generate the subquery
101 my $subq = $self->_select_args_to_query (
108 my $subq_joinspec = {
109 -alias => $attrs->{alias},
110 -source_handle => $inner_from[0]{-source_handle},
111 $attrs->{alias} => $subq,
114 # Generate the outer from - this is relatively easy (really just replace
115 # the join slot with the subquery), with a major caveat - we can not
116 # join anything that is non-selecting (not part of the prefetch), but at
117 # the same time is a multi-type relationship, as it will explode the result.
119 # There are two possibilities here
120 # - either the join is non-restricting, in which case we simply throw it away
121 # - it is part of the restrictions, in which case we need to collapse the outer
122 # result by tackling yet another group_by to the outside of the query
124 # so first generate the outer_from, up to the substitution point
126 while (my $j = shift @$from) {
127 if ($j->[0]{-alias} eq $attrs->{alias}) { # time to swap
132 last; # we'll take care of what's left in $from below
135 push @outer_from, $j;
139 # see what's left - throw away if not selecting/restricting
140 # also throw in a group_by if restricting to guard against
141 # cross-join explosions
143 while (my $j = shift @$from) {
144 my $alias = $j->[0]{-alias};
146 if ($select_aliases->{$alias} || $prefetch_aliases->{$alias}) {
147 push @outer_from, $j;
149 elsif ($restrict_aliases->{$alias}) {
150 push @outer_from, $j;
152 # FIXME - this should be obviated by SQLA2, as I'll be able to
153 # have restrict_inner and restrict_outer... or something to that
154 # effect... I think...
156 # FIXME2 - I can't find a clean way to determine if a particular join
157 # is a multi - instead I am just treating everything as a potential
158 # explosive join (ribasushi)
160 # if (my $handle = $j->[0]{-source_handle}) {
161 # my $rsrc = $handle->resolve;
162 # ... need to bail out of the following if this is not a multi,
163 # as it will be much easier on the db ...
165 $outer_attrs->{group_by} ||= $outer_select;
170 # demote the outer_from head
171 $outer_from[0] = $outer_from[0][0];
173 # This is totally horrific - the $where ends up in both the inner and outer query
174 # Unfortunately not much can be done until SQLA2 introspection arrives, and even
175 # then if where conditions apply to the *right* side of the prefetch, you may have
176 # to both filter the inner select (e.g. to apply a limit) and then have to re-filter
177 # the outer select to exclude joins you didin't want in the first place
179 # OTOH it can be seen as a plus: <ash> (notes that this query would make a DBA cry ;)
180 return (\@outer_from, $outer_select, $where, $outer_attrs);
183 sub _choose_aliases_to_include {
184 my ( $self, $from, $where, $inner_select, $inner_attrs, $outer_select,
187 my %original_join_info = map { $_->[0]{-alias} => $_->[0] } (@$from);
188 # decide which parts of the join will remain in either part of
189 # the outer/inner query
191 # First we compose a list of which aliases are used in restrictions
192 # (i.e. conditions/order/grouping/etc). Since we do not have
193 # introspectable SQLA, we fall back to ugly scanning of raw SQL for
194 # WHERE, and for pieces of ORDER BY in order to determine which aliases
195 # need to appear in the resulting sql.
196 # It may not be very efficient, but it's a reasonable stop-gap
197 # Also unqualified column names will not be considered, but more often
198 # than not this is actually ok
200 # In the same loop we enumerate part of the selection aliases, as
201 # it requires the same sqla hack for the time being
202 my ($restrict_aliases, $select_aliases, $prefetch_aliases);
204 # produce stuff unquoted, so it can be scanned
205 my $sql_maker = $self->sql_maker;
206 local $sql_maker->{quote_char};
207 my $sep = $self->_sql_maker_opts->{name_sep} || '.';
210 my $non_prefetch_select_sql = $sql_maker->_recurse_fields ($inner_select);
211 my $prefetch_select_sql = $sql_maker->_recurse_fields ($outer_attrs->{_prefetch_select});
212 my $where_sql = $sql_maker->where ($where);
213 my $group_by_sql = $sql_maker->_order_by({
214 map { $_ => $inner_attrs->{$_} } qw/group_by having/
216 my @non_prefetch_order_by_chunks = (map
217 { ref $_ ? $_->[0] : $_ }
218 $sql_maker->_order_by_chunks ($inner_attrs->{order_by})
222 for my $alias (keys %original_join_info) {
223 my $seen_re = qr/\b $alias $sep/x;
225 for my $piece ($where_sql, $group_by_sql, @non_prefetch_order_by_chunks ) {
226 if ($piece =~ $seen_re) {
227 $restrict_aliases->{$alias} = 1;
231 if ($non_prefetch_select_sql =~ $seen_re) {
232 $select_aliases->{$alias} = 1;
235 if ($prefetch_select_sql =~ $seen_re) {
236 $prefetch_aliases->{$alias} = 1;
242 # Add any non-left joins to the restriction list (such joins are indeed restrictions)
243 for my $j (values %original_join_info) {
244 my $alias = $j->{-alias} or next;
245 $restrict_aliases->{$alias} = 1 if (
246 (not $j->{-join_type})
248 ($j->{-join_type} !~ /^left (?: \s+ outer)? $/xi)
252 # mark all join parents as mentioned
253 # (e.g. join => { cds => 'tracks' } - tracks will need to bring cds too )
254 for my $collection ($restrict_aliases, $select_aliases) {
255 for my $alias (keys %$collection) {
256 $collection->{$_} = 1
257 for (@{ $original_join_info{$alias}{-join_path} || [] });
260 return ( $restrict_aliases, $select_aliases, $prefetch_aliases );
263 sub _resolve_ident_sources {
264 my ($self, $ident) = @_;
266 my $alias2source = {};
269 # the reason this is so contrived is that $ident may be a {from}
270 # structure, specifying multiple tables to join
271 if ( Scalar::Util::blessed($ident) && $ident->isa("DBIx::Class::ResultSource") ) {
272 # this is compat mode for insert/update/delete which do not deal with aliases
273 $alias2source->{me} = $ident;
276 elsif (ref $ident eq 'ARRAY') {
280 if (ref $_ eq 'HASH') {
282 $rs_alias = $tabinfo->{-alias};
284 if (ref $_ eq 'ARRAY' and ref $_->[0] eq 'HASH') {
288 $alias2source->{$tabinfo->{-alias}} = $tabinfo->{-source_handle}->resolve
289 if ($tabinfo->{-source_handle});
293 return ($alias2source, $rs_alias);
296 # Takes $ident, \@column_names
298 # returns { $column_name => \%column_info, ... }
299 # also note: this adds -result_source => $rsrc to the column info
301 # If no columns_names are supplied returns info about *all* columns
303 sub _resolve_column_info {
304 my ($self, $ident, $colnames) = @_;
305 my ($alias2src, $root_alias) = $self->_resolve_ident_sources($ident);
307 my $sep = $self->_sql_maker_opts->{name_sep} || '.';
308 my $qsep = quotemeta $sep;
310 my (%return, %seen_cols, @auto_colnames);
312 # compile a global list of column names, to be able to properly
313 # disambiguate unqualified column names (if at all possible)
314 for my $alias (keys %$alias2src) {
315 my $rsrc = $alias2src->{$alias};
316 for my $colname ($rsrc->columns) {
317 push @{$seen_cols{$colname}}, $alias;
318 push @auto_colnames, "$alias$sep$colname" unless $colnames;
324 grep { @{$seen_cols{$_}} == 1 } (keys %seen_cols),
328 foreach my $col (@$colnames) {
329 my ($alias, $colname) = $col =~ m/^ (?: ([^$qsep]+) $qsep)? (.+) $/x;
332 # see if the column was seen exactly once (so we know which rsrc it came from)
333 if ($seen_cols{$colname} and @{$seen_cols{$colname}} == 1) {
334 $alias = $seen_cols{$colname}[0];
341 my $rsrc = $alias2src->{$alias};
342 $return{$col} = $rsrc && {
343 %{$rsrc->column_info($colname)},
344 -result_source => $rsrc,
345 -source_alias => $alias,
352 # The DBIC relationship chaining implementation is pretty simple - every
353 # new related_relationship is pushed onto the {from} stack, and the {select}
354 # window simply slides further in. This means that when we count somewhere
355 # in the middle, we got to make sure that everything in the join chain is an
356 # actual inner join, otherwise the count will come back with unpredictable
357 # results (a resultset may be generated with _some_ rows regardless of if
358 # the relation which the $rs currently selects has rows or not). E.g.
359 # $artist_rs->cds->count - normally generates:
360 # SELECT COUNT( * ) FROM artist me LEFT JOIN cd cds ON cds.artist = me.artistid
361 # which actually returns the number of artists * (number of cds || 1)
363 # So what we do here is crawl {from}, determine if the current alias is at
364 # the top of the stack, and if not - make sure the chain is inner-joined down
367 sub _straight_join_to_node {
368 my ($self, $from, $alias) = @_;
370 # subqueries and other oddness are naturally not supported
376 ref $from->[0] ne 'HASH'
380 $from->[0]{-alias} eq $alias # this last bit means $alias is the head of $from - nothing to do
383 # find the current $alias in the $from structure
386 for my $j (@{$from}[1 .. $#$from]) {
387 if ($j->[0]{-alias} eq $alias) {
388 $switch_branch = $j->[0]{-join_path};
393 # something else went quite wrong
394 return $from unless $switch_branch;
396 # So it looks like we will have to switch some stuff around.
397 # local() is useless here as we will be leaving the scope
398 # anyway, and deep cloning is just too fucking expensive
399 # So replace the first hashref in the node arrayref manually
400 my @new_from = ($from->[0]);
401 my $sw_idx = { map { $_ => 1 } @$switch_branch };
403 for my $j (@{$from}[1 .. $#$from]) {
404 my $jalias = $j->[0]{-alias};
406 if ($sw_idx->{$jalias}) {
407 my %attrs = %{$j->[0]};
408 delete $attrs{-join_type};
422 # Most databases do not allow aliasing of tables in UPDATE/DELETE. Thus
423 # a condition containing 'me' or other table prefixes will not work
424 # at all. What this code tries to do (badly) is introspect the condition
425 # and remove all column qualifiers. If it bails out early (returns undef)
426 # the calling code should try another approach (e.g. a subquery)
427 sub _strip_cond_qualifiers {
428 my ($self, $where) = @_;
432 # No-op. No condition, we're updating/deleting everything
433 return $cond unless $where;
435 if (ref $where eq 'ARRAY') {
439 foreach my $key (keys %{$_}) {
441 $hash{$1} = $_->{$key};
447 elsif (ref $where eq 'HASH') {
448 if ( (keys %$where) == 1 && ( (keys %{$where})[0] eq '-and' )) {
450 my @cond = @{$where->{-and}};
451 for (my $i = 0; $i < @cond; $i++) {
452 my $entry = $cond[$i];
454 if (ref $entry eq 'HASH') {
455 $hash = $self->_strip_cond_qualifiers($entry);
458 $entry =~ /([^.]+)$/;
459 $hash->{$1} = $cond[++$i];
461 push @{$cond->{-and}}, $hash;
465 foreach my $key (keys %$where) {
467 $cond->{$1} = $where->{$key};