add first draft of intro doc for schema-based use

[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 7435d7b..b1ef52a 100644 (file)
--- a/lib/DBIx/Class/Relationship/BelongsTo.pm
+++ b/lib/DBIx/Class/Relationship/BelongsTo.pm
@@ -13,19 +13,30 @@ sub belongs_to {
   my %f_primaries;
   $f_primaries{$_} = 1 for eval { $f_class->primary_columns };
   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;
+  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 multiple primary key") if $too_many;
-    my $acc_type = ($class->has_column($rel)) ? 'filter' : 'single';
+    $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.${rel}" },
+      { "foreign.${pri}" => "self.${fk}" },
       { accessor => $acc_type, %{$attrs || {}} }
     );
   }
   # multiple key relationship
-  else {
+  elsif (ref $cond eq 'HASH') {
     my $cond_rel;
     for (keys %$cond) {
       if (m/\./) { # Explicit join condition
@@ -39,6 +50,9 @@ sub belongs_to {
       { accessor => 'single', %{$attrs || {}} }
     );
   }
+  else {
+    $class->throw('third argument for belongs_to must be undef, a column name, or a join condition');
+  }
   return 1;
 }