Check relationship declarations more consistently

[dbsrgits/DBIx-Class.git] / lib / DBIx / Class / Relationship / BelongsTo.pm

diff --git a/lib/DBIx/Class/Relationship/BelongsTo.pm b/lib/DBIx/Class/Relationship/BelongsTo.pm
index 326a99a..f6ce3a5 100644 (file)
--- a/lib/DBIx/Class/Relationship/BelongsTo.pm
+++ b/lib/DBIx/Class/Relationship/BelongsTo.pm
@@ -1,68 +1,114 @@
-package DBIx::Class::Relationship::BelongsTo;
+package # hide from PAUSE
+    DBIx::Class::Relationship::BelongsTo;
+
+# Documentation for these methods can be found in
+# DBIx::Class::Relationship
 
 use strict;
 use warnings;
+use Try::Tiny;
+use namespace::clean;
+
+our %_pod_inherit_config =
+  (
+   class_map => { 'DBIx::Class::Relationship::BelongsTo' => 'DBIx::Class::Relationship' }
+  );
 
 sub belongs_to {
   my ($class, $rel, $f_class, $cond, $attrs) = @_;
-  eval "require $f_class";
-  if ($@) {
-    $class->throw($@) unless $@ =~ /Can't locate/;
-  }
 
-  my %f_primaries;
-  $f_primaries{$_} = 1 for eval { $f_class->primary_columns };
-  my $f_loaded = !$@;
-  
-  # single key relationship
+  # assume a foreign key constraint unless defined otherwise
+  $attrs->{is_foreign_key_constraint} = 1
+    if not exists $attrs->{is_foreign_key_constraint};
+  $attrs->{undef_on_null_fk} = 1
+    if not exists $attrs->{undef_on_null_fk};
+
+  # no join condition or just a column name
   if (!ref $cond) {
-    $class->throw("Can't infer join condition for ${rel} on ${class}; unable to load ${f_class}")
-      unless $f_loaded;
-
-    my ($pri, $too_many) = keys %f_primaries;
-    $class->throw("Can't infer join condition for ${rel} on ${class}; ${f_class} has no primary keys")
-      unless defined $pri;      
-    $class->throw("Can't infer join condition for ${rel} on ${class}; ${f_class} has multiple primary key")
-      if $too_many;      
-
-    my $fk = defined $cond ? $cond : $rel;
-    $class->throw("Can't infer join condition for ${rel} on ${class}; $fk is not a column")
-      unless $class->has_column($fk);
-
-    my $acc_type = $class->has_column($rel) ? 'filter' : 'single';
-    $class->add_relationship($rel, $f_class,
-      { "foreign.${pri}" => "self.${fk}" },
-      { accessor => $acc_type, %{$attrs || {}} }
-    );
-  }
-  # multiple key relationship
-  elsif (ref $cond eq 'HASH') {
-    my $cond_rel;
-    for (keys %$cond) {
-      if (m/\./) { # Explicit join condition
-        $cond_rel = $cond;
-        last;
-      }
-      $cond_rel->{"foreign.$_"} = "self.".$cond->{$_};
+
+    my ($f_key, $guess);
+    if (defined $cond and length $cond) {
+      $f_key = $cond;
+      $guess = "caller specified foreign key '$f_key'";
+    }
+    else {
+      $f_key = $rel;
+      $guess = "using given relationship name '$rel' as foreign key column name";
+    }
+
+    $class->throw_exception(
+      "No such column '$f_key' declared yet on ${class} ($guess)"
+    )  unless $class->has_column($f_key);
+
+    $class->ensure_class_loaded($f_class);
+    my $f_rsrc = try {
+      $f_class->result_source_instance;
     }
-    my $acc_type = (scalar keys %$cond_rel == 1) ? 'filter' : 'single';
-    $class->add_relationship($rel, $f_class,
-      $cond_rel,
-      { accessor => $acc_type, %{$attrs || {}} }
-    );
+    catch {
+      $class->throw_exception(
+        "Foreign class '$f_class' does not seem to be a Result class "
+      . "(or it simply did not load entirely due to a circular relation chain)"
+      );
+    };
+
+    my $pri = $f_rsrc->_single_pri_col_or_die;
+
+    $cond = { "foreign.${pri}" => "self.${f_key}" };
+
   }
+  # explicit join condition
   else {
-    $class->throw('third argument for belongs_to must be undef, a column name, or a join condition');
+    if (ref $cond eq 'HASH') { # ARRAY is also valid
+      my $cond_rel;
+      # FIXME This loop is ridiculously incomplete and dangerous
+      # staving off changes until implmentation of the swindon consensus
+      for (keys %$cond) {
+        if (m/\./) { # Explicit join condition
+          $cond_rel = $cond;
+          last;
+        }
+        $cond_rel->{"foreign.$_"} = "self.".$cond->{$_};
+      }
+      $cond = $cond_rel;
+    }
   }
-  return 1;
-}
 
-=head1 AUTHORS
+  my $acc_type = (
+    ref $cond eq 'HASH'
+      and
+    keys %$cond == 1
+      and
+    (keys %$cond)[0] =~ /^foreign\./
+      and
+    $class->has_column($rel)
+  ) ? 'filter' : 'single';
 
-Alexander Hartmaier <Alexander.Hartmaier@t-systems.at>
+  my $fk_columns = ($acc_type eq 'single' and ref $cond eq 'HASH')
+    ? { map { $_ =~ /^self\.(.+)/ ? ( $1 => 1 ) : () } (values %$cond ) }
+    : undef
+  ;
+
+  $class->add_relationship($rel, $f_class,
+    $cond,
+    {
+      is_depends_on => 1,
+      accessor => $acc_type,
+      $fk_columns ? ( fk_columns => $fk_columns ) : (),
+      %{$attrs || {}}
+    }
+  );
+
+  return 1;
+}
 
-Matt S. Trout <mst@shadowcatsystems.co.uk>
+# Attempt to remove the POD so it (maybe) falls off the indexer
 
-=cut
+#=head1 AUTHORS
+#
+#Alexander Hartmaier <Alexander.Hartmaier@t-systems.at>
+#
+#Matt S. Trout <mst@shadowcatsystems.co.uk>
+#
+#=cut
 
 1;