X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FRelationship%2FBase.pm;h=cf82677764c7895086fb64f9bf9632b22bee08d2;hb=03f6d1f7;hp=f4b2bb2ce605e77b273027b00a617017f06bdd07;hpb=47d7b769c034e04989840b1efc2f5991518cff23;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/Relationship/Base.pm b/lib/DBIx/Class/Relationship/Base.pm index f4b2bb2..cf82677 100644 --- a/lib/DBIx/Class/Relationship/Base.pm +++ b/lib/DBIx/Class/Relationship/Base.pm @@ -54,9 +54,16 @@ source, indicated by its class name. The condition argument describes the C clause of the C expression used to connect the two sources when creating SQL queries. -To create simple equality joins, supply a hashref containing the -remote table column name as the key(s), and the local table column -name as the value(s), for example given: +=head4 Simple equality + +To create simple equality joins, supply a hashref containing the remote +table column name as the key(s) prefixed by C<'foreign.'>, and the +corresponding local table column name as the value(s) prefixed by C<'self.'>. +Both C and C are pseudo aliases and must be entered +literally. They will be replaced with the actual correct table alias +when the SQL is produced. + +For example given: My::Schema::Author->has_many( books => 'My::Schema::Book', @@ -75,10 +82,6 @@ This describes a relationship between the C table and the C table where the C table has a column C containing the ID value of the C. -C and C are pseudo aliases and must be entered -literally. They will be replaced with the actual correct table alias -when the SQL is produced. - Similarly: My::Schema::Book->has_many( @@ -103,9 +106,11 @@ will result in the C clause: This describes the relationship from C to C, where the C table refers to a publisher and a type (e.g. "paperback"): +=head4 Multiple groups of simple equality conditions + As is the default in L, the key-value pairs will be -Ced in the result. C can be achieved with an arrayref, for -example a condition like: +Ced in the resulting C clause. An C can be achieved with +an arrayref. For example a condition like: My::Schema::Item->has_many( related_item_links => My::Schema::Item::Links, @@ -125,6 +130,14 @@ This describes the relationship from C to C, where C is a many-to-many linking table, linking items back to themselves in a peer fashion (without a "parent-child" designation) +=head4 Custom join conditions + + NOTE: The custom join condition specification mechanism is capable of + generating JOIN clauses of virtually unlimited complexity. This may limit + your ability to traverse some of the more involved relationship chains the + way you expect, *and* may bring your RDBMS to its knees. Exercise care + when declaring relationships as described here. + To specify joins which describe more than a simple equality of column values, the custom join condition coderef syntax can be used. For example: @@ -212,7 +225,7 @@ hashref which does not depend on joins being available, but the hashref must contain only plain values/deflatable objects, such that the result can be passed directly to L. For instance the C constraint in the above example prevents the relationship -from being used to to create related objects (an exception will be thrown). +from being used to create related objects (an exception will be thrown). In order to allow the user to go truly crazy when generating a custom C clause, the C<$args> hashref passed to the subroutine contains some extra @@ -275,7 +288,7 @@ Then, assuming MyApp::Schema::LinerNotes has an accessor named notes, you can do For a 'belongs_to relationship, note the 'cascade_update': - MyApp::Schema::Track->belongs_to( cd => 'DBICTest::Schema::CD', 'cd, + MyApp::Schema::Track->belongs_to( cd => 'MyApp::Schema::CD', 'cd, { proxy => ['title'], cascade_update => 1 } ); $track->title('New Title'); @@ -284,9 +297,9 @@ For a 'belongs_to relationship, note the 'cascade_update': =item \%column A hashref where each key is the accessor you want installed in the main class, -and its value is the name of the original in the fireign class. +and its value is the name of the original in the foreign class. - MyApp::Schema::Track->belongs_to( cd => 'DBICTest::Schema::CD', 'cd', { + MyApp::Schema::Track->belongs_to( cd => 'MyApp::Schema::CD', 'cd', { proxy => { cd_title => 'title' }, }); @@ -296,7 +309,7 @@ This will create an accessor named C on the C<$track> result object. NOTE: you can pass a nested struct too, for example: - MyApp::Schema::Track->belongs_to( cd => 'DBICTest::Schema::CD', 'cd', { + MyApp::Schema::Track->belongs_to( cd => 'MyApp::Schema::CD', 'cd', { proxy => [ 'year', { cd_title => 'title' } ], }); @@ -470,18 +483,12 @@ sub related_resultset { $rsrc->_resolve_condition( $rel_info->{cond}, $rel, $self, $rel ) } catch { - if ($self->in_storage) { - $self->throw_exception ($_); - } - - $DBIx::Class::ResultSource::UNRESOLVABLE_CONDITION; # RV + $self->throw_exception ($_) if $self->in_storage; + $DBIx::Class::ResultSource::UNRESOLVABLE_CONDITION; # RV, no return() }; # keep in mind that the following if() block is part of a do{} - no return()s!!! - if ($is_crosstable) { - $self->throw_exception ( - "A cross-table relationship condition returned for statically declared '$rel'" - ) unless ref $rel_info->{cond} eq 'CODE'; + if ($is_crosstable and ref $rel_info->{cond} eq 'CODE') { # A WHOREIFFIC hack to reinvoke the entire condition resolution # with the correct alias. Another way of doing this involves a @@ -627,14 +634,20 @@ sub new_related { if (ref $self) { # cdbi calls this as a class method, /me vomits my $rsrc = $self->result_source; - my (undef, $crosstable, $cond_targets) = $rsrc->_resolve_condition ( - $rsrc->relationship_info($rel)->{cond}, $rel, $self, $rel + my $rel_info = $rsrc->relationship_info($rel) + or $self->throw_exception( "No such relationship '$rel'" ); + my (undef, $crosstable, $nonequality_foreign_columns) = $rsrc->_resolve_condition ( + $rel_info->{cond}, $rel, $self, $rel ); $self->throw_exception("Custom relationship '$rel' does not resolve to a join-free condition fragment") if $crosstable; - if (my @unspecified_rel_condition_chunks = grep { ! exists $values->{$_} } @{$cond_targets||[]} ) { + if ( + $nonequality_foreign_columns + and + my @unspecified_rel_condition_chunks = grep { ! exists $values->{$_} } @$nonequality_foreign_columns + ) { $self->throw_exception(sprintf ( "Custom relationship '%s' not definitive - returns conditions instead of values for column(s): %s", $rel, @@ -803,16 +816,17 @@ sub set_from_related { # # sanity check - currently throw when a complex coderef rel is encountered # FIXME - should THROW MOAR! - my ($cond, $crosstable, $cond_targets) = $rsrc->_resolve_condition ( + my ($cond, $crosstable, $nonequality_foreign_columns) = $rsrc->_resolve_condition ( $rel_info->{cond}, $f_obj, $rel, $rel ); $self->throw_exception("Custom relationship '$rel' does not resolve to a join-free condition fragment") if $crosstable; + $self->throw_exception(sprintf ( "Custom relationship '%s' not definitive - returns conditions instead of values for column(s): %s", $rel, - map { "'$_'" } @$cond_targets - )) if $cond_targets; + map { "'$_'" } @$nonequality_foreign_columns + )) if $nonequality_foreign_columns; $self->set_columns($cond);