我想将一个Str强制转换为我的Moose类中的属性的DBIx :: Class :: Row对象.为此,我需要在DBIC模式上执行查找以查找行.如果查找失败,我想将错误推送到ArrayRef属性.
我目前将模式作为属性传递给我的类.
有了强制,我似乎无法访问该对象,因此我无法推送错误的arrayref属性或使用模式对象来执行查找.
我尝试的另一种方法是使用’around’来查找并设置属性,但是当通过构造函数传递属性值时,这当然不会被调用.
这是可能的,还是有人有替代实现来做我想要实现的目标？
解决方法
当传递给具有属性初始值设定项的构造函数时,您可以捕获并改变存储的值. (但是,它仅在构造函数中设置属性时运行,而不是在任何其他时间运行.)初始值设定项的文档可在
Class::MOP::Attribute中找到.
由于这只捕获通过构造函数设置属性的情况,因此您仍然需要捕获设置该属性的其他情况.这可以通过你所说的方法修饰符来完成,但你可以将这两个方法组合成一个方法,包裹在自动生成的访问器中：
has my_attr => (
is => 'rw',isa => 'DBIx::Class::Row',initializer => 'my_attr',);
# my_attr is the autogenerated accessor - we method-modify it to mutate the
# value being set,and catch cases where it is called as an initializer.
# called for reads,writes,and on initialization at construction time
around 'my_attr' => sub {
my $orig = shift;
my $self = shift;
# value is not defined if being called as a reader
# setter and attr are only defined if being called as an initializer
my ($value,$setter,$attr) = @_;
# the reader behaves normally
return $self->$orig if not @_;
# convert the string to the row object
my $row = $self->convert_str_to_row_obj($value);
# if called as an initializer,set the value and we're done
return $setter->($row) if $setter;
# otherwise,call the real writer with the new value
$self->$orig($row);
};