fix conditions on Compositions : 2nd multiplicity can be 0..n _or_ 0..1

damil · Apr 25, 2024 · 1288702 · 1288702
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commit 1288702
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Showing 4 changed files with 5 additions and 6 deletions.
diff --git a/lib/DBIx/DataModel/Doc/Quickstart.pod b/lib/DBIx/DataModel/Doc/Quickstart.pod
@@ -272,7 +272,6 @@ we will introduce the new concept of I<composition>.
                   [qw/Activity   activities  * /]);
 
 This looks exactly like an association declaration; but it states that
-
 an activity somehow "belongs" to an employee (cannot exist without
 being attached to an employee). In a UML class diagram, this would be
 pictured with a black diamond on the Employee side.  In this

diff --git a/lib/DBIx/DataModel/Doc/Reference.pod b/lib/DBIx/DataModel/Doc/Reference.pod
@@ -719,7 +719,7 @@ of kind C<Composition> is :
 
 =item *
 
-the multiplicity must be 1-to-n
+the multiplicity must be 1-to-n or 1-to-0..1
 
 =item * 
 

diff --git a/lib/DBIx/DataModel/Meta/Association.pm b/lib/DBIx/DataModel/Meta/Association.pm
@@ -227,8 +227,8 @@ sub _check_composition {
   # multiplicities must be 1-to-n
   $self->{A}{multiplicity}[1] == 1
     or croak "max multiplicity of first class in a composition must be 1";
-  $self->{B}{multiplicity}[1] > 1
-    or croak "max multiplicity of second class in a composition must be > 1";
+  $self->{B}{multiplicity}[0] == 0
+    or croak "min multiplicity of second class in a composition must be 0";
 
   # check for conflicting compositions
   while (my ($name, $path) = each %{$self->{B}{table}{path} || {}}) {
@@ -402,7 +402,7 @@ Special behaviour is attached to the kind C<Composition> :
 
 =item *
 
-the multiplicity must be 1-to-n
+the multiplicity must be 1-to-n or 1-to-0..1
 
 =item * 
 

diff --git a/lib/DBIx/DataModel/Meta/Path.pm b/lib/DBIx/DataModel/Meta/Path.pm
@@ -43,7 +43,7 @@ sub new {
 
   # if this is a composition path, remember it in the 'components' array
   push @{$self->{from}{components}}, $path
-    if $self->{association}{kind} eq 'Composition' && $self->{multiplicity}[1] > 1;
+    if $self->{association}{kind} eq 'Composition' && $self->{multiplicity}[0] == 0;
 
   # install a navigation method into the 'from' table class
   my @navigation_args = ($self->{name},  # method name