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[dbsrgits/DBIx-Class-Historic.git] / lib / DBIx / Class / SQLAHacks / OracleJoins.pm
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6f4ddea1 1package # Hide from PAUSE
855c6fd0 2 DBIx::Class::SQLAHacks::OracleJoins;
6f4ddea1 3
4use base qw( DBIx::Class::SQLAHacks );
87aa29e2 5use Carp::Clan qw/^DBIx::Class|^SQL::Abstract/;
6f4ddea1 6
7sub select {
8 my ($self, $table, $fields, $where, $order, @rest) = @_;
9
10 if (ref($table) eq 'ARRAY') {
11 $where = $self->_oracle_joins($where, @{ $table });
12 }
13
14 return $self->SUPER::select($table, $fields, $where, $order, @rest);
15}
16
17sub _recurse_from {
18 my ($self, $from, @join) = @_;
19
20 my @sqlf = $self->_make_as($from);
21
22 foreach my $j (@join) {
23 my ($to, $on) = @{ $j };
24
25 if (ref $to eq 'ARRAY') {
26 push (@sqlf, $self->_recurse_from(@{ $to }));
27 }
28 else {
29 push (@sqlf, $self->_make_as($to));
30 }
31 }
32
33 return join q{, }, @sqlf;
34}
35
36sub _oracle_joins {
37 my ($self, $where, $from, @join) = @_;
38 my $join_where = {};
39 $self->_recurse_oracle_joins($join_where, $from, @join);
40 if (keys %$join_where) {
41 if (!defined($where)) {
42 $where = $join_where;
43 } else {
44 if (ref($where) eq 'ARRAY') {
45 $where = { -or => $where };
46 }
47 $where = { -and => [ $join_where, $where ] };
48 }
49 }
50 return $where;
51}
52
53sub _recurse_oracle_joins {
54 my ($self, $where, $from, @join) = @_;
55
56 foreach my $j (@join) {
57 my ($to, $on) = @{ $j };
58
59 if (ref $to eq 'ARRAY') {
60 $self->_recurse_oracle_joins($where, @{ $to });
61 }
62
63 my $to_jt = ref $to eq 'ARRAY' ? $to->[0] : $to;
64 my $left_join = q{};
65 my $right_join = q{};
66
67 if (ref $to_jt eq 'HASH' and exists $to_jt->{-join_type}) {
68 #TODO: Support full outer joins -- this would happen much earlier in
69 #the sequence since oracle 8's full outer join syntax is best
70 #described as INSANE.
e8fcf76f 71 croak "Can't handle full outer joins in Oracle 8 yet!\n"
6f4ddea1 72 if $to_jt->{-join_type} =~ /full/i;
73
74 $left_join = q{(+)} if $to_jt->{-join_type} =~ /left/i
75 && $to_jt->{-join_type} !~ /inner/i;
76
77 $right_join = q{(+)} if $to_jt->{-join_type} =~ /right/i
78 && $to_jt->{-join_type} !~ /inner/i;
79 }
80
81 foreach my $lhs (keys %{ $on }) {
82 $where->{$lhs . $left_join} = \"= $on->{ $lhs }$right_join";
83 }
84 }
85}
86
871;
88
89=pod
90
91=head1 NAME
92
93DBIx::Class::SQLAHacks::OracleJoins - Pre-ANSI Joins-via-Where-Clause Syntax
94
95=head1 PURPOSE
96
97This module was originally written to support Oracle < 9i where ANSI joins
98weren't supported at all, but became the module for Oracle >= 8 because
99Oracle's optimising of ANSI joins is horrible. (See:
100http://scsys.co.uk:8001/7495)
101
102=head1 SYNOPSIS
103
104Not intended for use directly; used as the sql_maker_class for schemas and components.
105
106=head1 DESCRIPTION
107
108Implements pre-ANSI joins specified in the where clause. Instead of:
109
110 SELECT x FROM y JOIN z ON y.id = z.id
111
112It will write:
113
114 SELECT x FROM y, z WHERE y.id = z.id
115
116It should properly support left joins, and right joins. Full outer joins are
117not possible due to the fact that Oracle requires the entire query be written
118to union the results of a left and right join, and by the time this module is
119called to create the where query and table definition part of the sql query,
120it's already too late.
121
122=head1 METHODS
123
124=over
125
126=item select ($\@$;$$@)
127
128Replaces DBIx::Class::SQLAHacks's select() method, which calls _oracle_joins()
129to modify the column and table list before calling SUPER::select().
130
131=item _recurse_from ($$\@)
132
133Recursive subroutine that builds the table list.
134
135=item _oracle_joins ($$$@)
136
137Creates the left/right relationship in the where query.
138
139=back
140
141=head1 BUGS
142
143Does not support full outer joins.
144Probably lots more.
145
146=head1 SEE ALSO
147
148=over
149
150=item L<DBIx::Class::Storage::DBI::Oracle::WhereJoins> - Storage class using this
151
152=item L<DBIx::Class::SQLAHacks> - Parent module
153
154=item L<DBIx::Class> - Duh
155
156=back
157
158=head1 AUTHOR
159
160Justin Wheeler C<< <jwheeler@datademons.com> >>
161
162=head1 CONTRIBUTORS
163
164David Jack Olrik C<< <djo@cpan.org> >>
165
166=head1 LICENSE
167
168This module is licensed under the same terms as Perl itself.
169
170=cut
171