X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FRelationship%2FBase.pm;h=a41d6b4df0b1d15874a6df2da4f58f93f087e2de;hb=a5fc497548f9f980d3fd1deb7b7cb9095d079651;hp=5338cb67120213a12a310544536c19a7059c7d1a;hpb=4b8a53eabdb1629bacdb95f04ca8fc3718ca7c58;p=dbsrgits%2FDBIx-Class.git

diff --git a/lib/DBIx/Class/Relationship/Base.pm b/lib/DBIx/Class/Relationship/Base.pm
index 5338cb6..a41d6b4 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<ON> clause of the C<JOIN>
 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<foreign> and C<self> 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<Author> table and the
 C<Book> table where the C<Book> table has a column C<author_id>
 containing the ID value of the C<Author>.
 
-C<foreign> and C<self> 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<JOIN> clause:
 This describes the relationship from C<Book> to C<Edition>, where the
 C<Edition> table refers to a publisher and a type (e.g. "paperback"):
 
+=head4 Multiple groups of simple equality conditions
+
 As is the default in L<SQL::Abstract>, the key-value pairs will be
-C<AND>ed in the result. C<OR> can be achieved with an arrayref, for
-example a condition like:
+C<AND>ed in the resulting C<JOIN> clause. An C<OR> 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<Item> to C<Item::Links>, where
 C<Item::Links> 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:
@@ -206,13 +219,13 @@ With the bind values:
     '4', '1990', '1979'
 
 Note that in order to be able to use
-L<< $row->create_related|DBIx::Class::Relationship::Base/create_related >>,
+L<< $result->create_related|DBIx::Class::Relationship::Base/create_related >>,
 the coderef must not only return as its second such a "simple" condition
 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<DBIx::Class::Relationship::Base/set_from_related>. For
 instance the C<year> 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<ON>
 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<cd_title> 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' } ],
   });
 
@@ -423,8 +436,8 @@ $rel_name.
 =back
 
   # These pairs do the same thing
-  $row = $cd->related_resultset('artist')->single;  # has_one relationship
-  $row = $cd->artist;
+  $result = $cd->related_resultset('artist')->single;  # has_one relationship
+  $result = $cd->artist;
   $rs = $cd->related_resultset('tracks');           # has_many relationship
   $rs = $cd->tracks;
 
@@ -441,14 +454,20 @@ this instance (like in the case of C<might_have> relationships).
 
 sub related_resultset {
   my $self = shift;
+
   $self->throw_exception("Can't call *_related as class methods")
     unless ref $self;
+
   my $rel = shift;
-  my $rel_info = $self->relationship_info($rel);
-  $self->throw_exception( "No such relationship ${rel}" )
-    unless $rel_info;
 
-  return $self->{related_resultsets}{$rel} ||= do {
+  return $self->{related_resultsets}{$rel}
+    if defined $self->{related_resultsets}{$rel};
+
+  return $self->{related_resultsets}{$rel} = do {
+
+    my $rel_info = $self->relationship_info($rel)
+      or $self->throw_exception( "No such relationship '$rel'" );
+
     my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {});
     $attrs = { %{$rel_info->{attrs} || {}}, %$attrs };
 
@@ -456,12 +475,12 @@ sub related_resultset {
       if (@_ > 1 && (@_ % 2 == 1));
     my $query = ((@_ > 1) ? {@_} : shift);
 
-    my $source = $self->result_source;
+    my $rsrc = $self->result_source;
 
     # condition resolution may fail if an incomplete master-object prefetch
     # is encountered - that is ok during prefetch construction (not yet in_storage)
     my ($cond, $is_crosstable) = try {
-      $source->_resolve_condition( $rel_info->{cond}, $rel, $self, $rel )
+      $rsrc->_resolve_condition( $rel_info->{cond}, $rel, $self, $rel )
     }
     catch {
       if ($self->in_storage) {
@@ -474,8 +493,8 @@ sub related_resultset {
     # 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 $rel_info->{cond} eq 'CODE';
+        "A cross-table relationship condition returned for statically declared '$rel'"
+      ) unless 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
@@ -487,11 +506,11 @@ sub related_resultset {
       # root alias as 'me', instead of $rel (as opposed to invoking
       # $rs->search_related)
 
-      local $source->{_relationships}{me} = $source->{_relationships}{$rel};  # make the fake 'me' rel
-      my $obj_table_alias = lc($source->source_name) . '__row';
+      local $rsrc->{_relationships}{me} = $rsrc->{_relationships}{$rel};  # make the fake 'me' rel
+      my $obj_table_alias = lc($rsrc->source_name) . '__row';
       $obj_table_alias =~ s/\W+/_/g;
 
-      $source->resultset->search(
+      $rsrc->resultset->search(
         $self->ident_condition($obj_table_alias),
         { alias => $obj_table_alias },
       )->search_related('me', $query, $attrs)
@@ -501,7 +520,7 @@ sub related_resultset {
       # at some point what it does. Also the entire UNRESOLVABLE_CONDITION
       # business seems shady - we could simply not query *at all*
       if ($cond eq $DBIx::Class::ResultSource::UNRESOLVABLE_CONDITION) {
-        my $reverse = $source->reverse_relationship_info($rel);
+        my $reverse = $rsrc->reverse_relationship_info($rel);
         foreach my $rev_rel (keys %$reverse) {
           if ($reverse->{$rev_rel}{attrs}{accessor} && $reverse->{$rev_rel}{attrs}{accessor} eq 'multi') {
             weaken($attrs->{related_objects}{$rev_rel}[0] = $self);
@@ -531,7 +550,7 @@ sub related_resultset {
       }
 
       $query = ($query ? { '-and' => [ $cond, $query ] } : $cond);
-      $self->result_source->related_source($rel)->resultset->search(
+      $rsrc->related_source($rel)->resultset->search(
         $query, $attrs
       );
     }
@@ -621,18 +640,20 @@ sub new_related {
   if (ref $self) {  # cdbi calls this as a class method, /me vomits
 
     my $rsrc = $self->result_source;
-    my (undef, $crosstable, $relcols) = $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, $cond_targets) = $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 (@{$relcols || []} and @$relcols = grep { ! exists $values->{$_} } @$relcols) {
+    if (my @unspecified_rel_condition_chunks = grep { ! exists $values->{$_} } @{$cond_targets||[]} ) {
       $self->throw_exception(sprintf (
         "Custom relationship '%s' not definitive - returns conditions instead of values for column(s): %s",
         $rel,
-        map { "'$_'" } @$relcols
+        map { "'$_'" } @unspecified_rel_condition_chunks
       ));
     }
   }
@@ -781,11 +802,11 @@ sub set_from_related {
 
   my $rsrc = $self->result_source;
   my $rel_info = $rsrc->relationship_info($rel)
-    or $self->throw_exception( "No such relationship ${rel}" );
+    or $self->throw_exception( "No such relationship '$rel'" );
 
   if (defined $f_obj) {
     my $f_class = $rel_info->{class};
-    $self->throw_exception( "Object $f_obj isn't a ".$f_class )
+    $self->throw_exception( "Object '$f_obj' isn't a ".$f_class )
       unless blessed $f_obj and $f_obj->isa($f_class);
   }
 
@@ -797,7 +818,7 @@ sub set_from_related {
   #
   # sanity check - currently throw when a complex coderef rel is encountered
   # FIXME - should THROW MOAR!
-  my ($cond, $crosstable, $relcols) = $rsrc->_resolve_condition (
+  my ($cond, $crosstable, $cond_targets) = $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")
@@ -805,8 +826,8 @@ sub set_from_related {
   $self->throw_exception(sprintf (
     "Custom relationship '%s' not definitive - returns conditions instead of values for column(s): %s",
     $rel,
-    map { "'$_'" } @$relcols
-  )) if @{$relcols || []};
+    map { "'$_'" } @$cond_targets
+  )) if $cond_targets;
 
   $self->set_columns($cond);