CPANDB
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lib/CPANDB/Distribution.pod view on Meta::CPAN
from time to time you may need it programatically. If you do need it,
you can use the C<table> method to get the table name.
=head2 load
my $object = CPANDB::Distribution->load( $distribution );
If your table has single column primary key, a C<load> method will be
generated in the class. If there is no primary key, the method is not
created.
The C<load> method provides a shortcut mechanism for fetching a single
object based on the value of the primary key. However it should only
be used for cases where your code trusts the record to already exists.
It returns a C<CPANDB::Distribution> object, or throws an exception if the
object does not exist.
=head2 select
# Get all objects in list context
my @list = CPANDB::Distribution->select;
# Get a subset of objects in scalar context
my $array_ref = CPANDB::Distribution->select(
'where distribution > ? order by distribution',
1000,
);
The C<select> method executes a typical SQL C<SELECT> query on the
distribution table.
It takes an optional argument of a SQL phrase to be added after the
C<FROM distribution> section of the query, followed by variables
to be bound to the placeholders in the SQL phrase. Any SQL that is
compatible with SQLite can be used in the parameter.
Returns a list of B<CPANDB::Distribution> objects when called in list context, or a
reference to an C<ARRAY> of B<CPANDB::Distribution> objects when called in scalar
context.
Throws an exception on error, typically directly from the L<DBI> layer.
=head2 iterate
CPANDB::Distribution->iterate( sub {
print $_->distribution . "\n";
} );
The C<iterate> method enables the processing of large tables one record at
a time without loading having to them all into memory in advance.
This plays well to the strength of SQLite, allowing it to do the work of
loading arbitrarily large stream of records from disk while retaining the
full power of Perl when processing the records.
The last argument to C<iterate> must be a subroutine reference that will be
called for each element in the list, with the object provided in the topic
variable C<$_>.
This makes the C<iterate> code fragment above functionally equivalent to the
following, except with an O(1) memory cost instead of O(n).
foreach ( CPANDB::Distribution->select ) {
print $_->distribution . "\n";
}
You can filter the list via SQL in the same way you can with C<select>.
CPANDB::Distribution->iterate(
'order by ?', 'distribution',
sub {
print $_->distribution . "\n";
}
);
You can also use it in raw form from the root namespace for better control.
Using this form also allows for the use of arbitrarily complex queries,
including joins. Instead of being objects, rows are provided as C<ARRAY>
references when used in this form.
CPANDB->iterate(
'select name from distribution order by distribution',
sub {
print $_->[0] . "\n";
}
);
=head2 count
# How many objects are in the table
my $rows = CPANDB::Distribution->count;
# How many objects
my $small = CPANDB::Distribution->count(
'where distribution > ?',
1000,
);
The C<count> method executes a C<SELECT COUNT(*)> query on the
distribution table.
It takes an optional argument of a SQL phrase to be added after the
C<FROM distribution> section of the query, followed by variables
to be bound to the placeholders in the SQL phrase. Any SQL that is
compatible with SQLite can be used in the parameter.
Returns the number of objects that match the condition.
Throws an exception on error, typically directly from the L<DBI> layer.
=head1 ACCESSORS
=head2 distribution
if ( $object->distribution ) {
print "Object has been inserted\n";
} else {
print "Object has not been inserted\n";
}
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