Alzabo::ForeignKey(3)
Foreign key (relation) objects
SYNOPSIS
use Alzabo::ForeignKey;
foreach my $fk ($table->foreign_keys)
{
print $fk->cardinality;
}
DESCRIPTION
A foreign key is an object defined by several properties. It
represents a relationship from a column or columns in one table to a
column or columns in another table.
This relationship is defined by its cardinality (one to one, one to
many, or many to one) and its dependencies (whether or not table X is
dependent on table Y, and vice versa).
Many to many relationships are not allowed. However, you may indicate
such a relationship when using the
Alzabo::Create::Schema->add_relation
method method, and it will create
the necessary intermediate linking table for you.
METHODS
table_from
table_to
Returns the relevant "Alzabo::Table" object.
columns_from
columns_to
Returns the relevant "Alzabo::Column" object(s) for
the property as an array.
column_pairs
Returns an array of array references. The references are to two
column array of "Alzabo::Column" objects. These
two columns correspond in the tables being linked together.
cardinality
Returns a two element array containing the two portions of the
cardinality of the relationship. Each portion will be either '1' or
'n'.
from_is_dependent
to_is_dependent
Returns a boolean value indicating whether there is a dependency from
one table to the other.
is_one_to_one
is_one_to_many
is_many_to_one
Returns a boolean value indicating what kind of relationship the
object represents.
is_same_relationship_as ($fk)
Given a foreign key object, this returns true if the two objects
represent the same relationship. However, the two objects may
represent the same relationship from different table's points of view.
id
Returns a string uniquely identifying the foreign key.
comment
Returns the comment associated with the foreign key object, if any.
