Add cookbook discussion of single() vs first()

[dbsrgits/DBIx-Class-Historic.git] / lib / DBIx / Class / ResultSet.pm

diff --git a/lib/DBIx/Class/ResultSet.pm b/lib/DBIx/Class/ResultSet.pm
index bcb27a4..11f275c 100644 (file)
--- a/lib/DBIx/Class/ResultSet.pm
+++ b/lib/DBIx/Class/ResultSet.pm
@@ -12,6 +12,7 @@ use Storable;
 use DBIx::Class::ResultSetColumn;
 use DBIx::Class::ResultSourceHandle;
 use List::Util ();
+use Scalar::Util ();
 use base qw/DBIx::Class/;
 
 __PACKAGE__->mk_group_accessors('simple' => qw/result_class _source_handle/);
@@ -1518,17 +1519,40 @@ sub new_result {
   my ($self, $values) = @_;
   $self->throw_exception( "new_result needs a hash" )
     unless (ref $values eq 'HASH');
-  $self->throw_exception(
-    "Can't abstract implicit construct, condition not a hash"
-  ) if ($self->{cond} && !(ref $self->{cond} eq 'HASH'));
 
+  my %new;
   my $alias = $self->{attrs}{alias};
-  my $collapsed_cond = $self->{cond} ? $self->_collapse_cond($self->{cond}) : {};
 
-  # precendence must be given to passed values over values inherited from the cond, 
-  # so the order here is important.
-  my %new = (
-    %{ $self->_remove_alias($collapsed_cond, $alias) },
+  if (
+    defined $self->{cond}
+    && $self->{cond} eq $DBIx::Class::ResultSource::UNRESOLVABLE_CONDITION
+  ) {
+    %new = %{$self->{attrs}{related_objects}};
+  } else {
+    $self->throw_exception(
+      "Can't abstract implicit construct, condition not a hash"
+    ) if ($self->{cond} && !(ref $self->{cond} eq 'HASH'));
+  
+    my $collapsed_cond = (
+      $self->{cond}
+        ? $self->_collapse_cond($self->{cond})
+        : {}
+    );
+  
+    # precendence must be given to passed values over values inherited from
+    # the cond, so the order here is important.
+    my %implied =  %{$self->_remove_alias($collapsed_cond, $alias)};
+    while( my($col,$value) = each %implied ){
+      if(ref($value) eq 'HASH' && keys(%$value) && (keys %$value)[0] eq '='){
+        $new{$col} = $value->{'='};
+        next;
+      }
+      $new{$col} = $value if $self->_is_deterministic_value($value);
+    }
+  }
+
+  %new = (
+    %new,
     %{ $self->_remove_alias($values, $alias) },
     -source_handle => $self->_source_handle,
     -result_source => $self->result_source, # DO NOT REMOVE THIS, REQUIRED
@@ -1537,6 +1561,20 @@ sub new_result {
   return $self->result_class->new(\%new);
 }
 
+# _is_deterministic_value
+#
+# Make an effor to strip non-deterministic values from the condition, 
+# to make sure new_result chokes less
+
+sub _is_deterministic_value {
+  my $self = shift;
+  my $value = shift;
+  my $ref_type = ref $value;
+  return 1 if $ref_type eq '' || $ref_type eq 'SCALAR';
+  return 1 if Scalar::Util::blessed($value);
+  return 0;
+}
+
 # _collapse_cond
 #
 # Recursively collapse the condition.
@@ -1726,6 +1764,12 @@ constraint. For example:
     { key => 'cd_artist_title' }
   );
 
+Note: Because find_or_create() reads from the database and then
+possibly inserts based on the result, this method is subject to a race
+condition. Another process could create a record in the table after
+the find has completed and before the create has started. To avoid
+this problem, use find_or_create() inside a transaction.
+
 See also L</find> and L</update_or_create>. For information on how to declare
 unique constraints, see L<DBIx::Class::ResultSource/add_unique_constraint>.