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.\" ========================================================================
.\"
.IX Title "Class::DBI::Cascade::None 3pm"
.TH Class::DBI::Cascade::None 3pm "2022-03-28" "perl v5.34.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
Class::DBI::Cascade::None \- Do nothing upon deletion
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This is a Cascading Delete strategy that will do nothing, leaving
orphaned records behind.
.PP
It is the base class for most ofther Cascade strategies, and so provides
several important methods:
.SH "CONSTRUCTOR"
.IX Header "CONSTRUCTOR"
.SS "new"
.IX Subsection "new"
.Vb 1
\&        my $strategy = Cascade::Class\->new($Relationship);
.Ve
.PP
This must be instantiated with a Class::DBI::Relationship object.
.SH "METHODS"
.IX Header "METHODS"
.SS "foreign_for"
.IX Subsection "foreign_for"
.Vb 1
\&        my $iterator = $strategy\->foreign_for($obj);
.Ve
.PP
This will return all the objects which are foreign to \f(CW$obj\fR across the
relationship. It's a normal Class::DBI search you can get the results
either as a list or as an iterator.
.SS "cascade"
.IX Subsection "cascade"
.Vb 1
\&        $strategy\->cascade($obj);
.Ve
.PP
Cascade across the related objects to \f(CW$obj\fR.
.SH "WRITING NEW STRATEGIES"
.IX Header "WRITING NEW STRATEGIES"
Creating a Cascade strategy should be fairly simple. You usually just
need to inherit from here, and then supply a \fBcascade()\fR method that does
the required thing with the results from \fBforeign_for()\fR.
.PP
So, for example, Cascade::Delete is implemented simply as:
.PP
.Vb 1
\&        package Class::DBI::Cascade::Delete;
\&
\&        use base \*(AqClass::DBI::Cascade::None\*(Aq;
\&
\&        sub cascade {
\&                my ($self, $obj) = @_;
\&                $self\->foreign_for($obj)\->delete_all;
\&        }
.Ve