rename option to undef_on_null_fk and make it default for belongs_to

[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 0cc441e..eb10752 100644 (file)
--- a/lib/DBIx/Class/Relationship/BelongsTo.pm
+++ b/lib/DBIx/Class/Relationship/BelongsTo.pm
@@ -1,37 +1,79 @@
-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;
 
 sub belongs_to {
   my ($class, $rel, $f_class, $cond, $attrs) = @_;
-  eval "require $f_class";
-  my %f_primaries = eval { %{ $f_class->_primaries } };
-  my $f_loaded = !$@;
-  # single key relationship
-  if (not defined $cond) {
-    $class->throw("Can't infer join condition for ${rel} on ${class}; unable to load ${f_class}") unless $f_loaded;
+
+  # assume a foreign key contraint 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) {
+    $class->ensure_class_loaded($f_class);
+    my %f_primaries = map { $_ => 1 } eval { $f_class->primary_columns };
+    $class->throw_exception(
+      "Can't infer join condition for ${rel} on ${class}; ".
+      "unable to load ${f_class}: $@"
+    ) if $@;
+
     my ($pri, $too_many) = keys %f_primaries;
-    $class->throw("Can't infer join condition for ${rel} on ${class}; ${f_class} has multiple primary key") if $too_many;
-    my $acc_type = ($class->_columns->{$rel}) ? 'filter' : 'single';
+    $class->throw_exception(
+      "Can't infer join condition for ${rel} on ${class}; ".
+      "${f_class} has no primary keys"
+    ) unless defined $pri;
+    $class->throw_exception(
+      "Can't infer join condition for ${rel} on ${class}; ".
+      "${f_class} has multiple primary keys"
+    ) if $too_many;
+
+    my $fk = defined $cond ? $cond : $rel;
+    $class->throw_exception(
+      "Can't infer join condition for ${rel} on ${class}; ".
+      "$fk is not a column of $class"
+    ) unless $class->has_column($fk);
+
+    my $acc_type = $class->has_column($rel) ? 'filter' : 'single';
     $class->add_relationship($rel, $f_class,
-      { "foreign.${pri}" => "self.${rel}" },
+      { "foreign.${pri}" => "self.${fk}" },
       { accessor => $acc_type, %{$attrs || {}} }
     );
   }
-  # multiple key relationship
-  else {
-    my $cond_rel;
-    for (keys %$cond) {
-      if (m/\./) { # Explicit join condition
-        $cond_rel = $cond;
-        last;
+  # explicit join condition
+  elsif (ref $cond) {
+    if (ref $cond eq 'HASH') { # ARRAY is also valid
+      my $cond_rel;
+      for (keys %$cond) {
+        if (m/\./) { # Explicit join condition
+          $cond_rel = $cond;
+          last;
+        }
+        $cond_rel->{"foreign.$_"} = "self.".$cond->{$_};
       }
-      $cond_rel->{"foreign.$_"} = "self.".$cond->{$_};
+      $cond = $cond_rel;
     }
+    my $acc_type = ((ref $cond eq 'HASH')
+                       && keys %$cond == 1
+                       && $class->has_column($rel))
+                     ? 'filter'
+                     : 'single';
     $class->add_relationship($rel, $f_class,
-      $cond_rel,
-      { accessor => 'single', %{$attrs || {}} }
+      $cond,
+      { accessor => $acc_type, %{$attrs || {}} }
+    );
+  }
+  else {
+    $class->throw_exception(
+      'third argument for belongs_to must be undef, a column name, '.
+      'or a join condition'
     );
   }
   return 1;