Cpandb class for the requires table
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# Returns 'CPANDB' my $namespace = CPANDB::Requires->base;
Normally you will only need to work directly with a table class, and only with one ORLite package.
However, if for some reason you need to work with multiple ORLite packages at the same time without hardcoding the root namespace all the time, you can determine the root namespace from an object or table class with the \*(C`base\*(C' method.
# Returns 'requires' print CPANDB::Requires->table;
While you should not need the name of table for any simple operations, from time to time you may need it programatically. If you do need it, you can use the \*(C`table\*(C' method to get the table name.
my $object = CPANDB::Requires->load( $distribution );
If your table has single column primary key, a \*(C`load\*(C' method will be generated in the class. If there is no primary key, the method is not created.
The \*(C`load\*(C' 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::Requires\*(C' object, or throws an exception if the object does not exist.
# Get all objects in list context my @list = CPANDB::Requires->select;
# Get a subset of objects in scalar context my $array_ref = CPANDB::Requires->select( 'where distribution > ? order by distribution', 1000, );
The \*(C`select\*(C' method executes a typical \s-1SQL\s0 \*(C`SELECT\*(C' query on the requires table.
It takes an optional argument of a \s-1SQL\s0 phrase to be added after the \*(C`FROM requires\*(C' section of the query, followed by variables to be bound to the placeholders in the \s-1SQL\s0 phrase. Any \s-1SQL\s0 that is compatible with SQLite can be used in the parameter.
Returns a list of CPANDB::Requires objects when called in list context, or a reference to an \*(C`ARRAY\*(C' of CPANDB::Requires objects when called in scalar context.
Throws an exception on error, typically directly from the \s-1DBI\s0 layer.
CPANDB::Requires->iterate( sub { print $_->distribution . "\n"; } );
The \*(C`iterate\*(C' 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\*(C' must be a subroutine reference that will be called for each element in the list, with the object provided in the topic variable $_.
This makes the \*(C`iterate\*(C' code fragment above functionally equivalent to the following, except with an O(1) memory cost instead of O(n).
foreach ( CPANDB::Requires->select ) { print $_->distribution . "\n"; }
You can filter the list via \s-1SQL\s0 in the same way you can with \*(C`select\*(C'.
CPANDB::Requires->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\*(C' references when used in this form.
CPANDB->iterate( 'select name from requires order by distribution', sub { print $_->[0] . "\n"; } );
# How many objects are in the table my $rows = CPANDB::Requires->count;
# How many objects my $small = CPANDB::Requires->count( 'where distribution > ?', 1000, );
The \*(C`count\*(C' method executes a \*(C`SELECT COUNT(*)\*(C' query on the requires table.
It takes an optional argument of a \s-1SQL\s0 phrase to be added after the \*(C`FROM requires\*(C' section of the query, followed by variables to be bound to the placeholders in the \s-1SQL\s0 phrase. Any \s-1SQL\s0 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 \s-1DBI\s0 layer.
if ( $object->distribution ) { print "Object has been inserted\n"; } else { print "Object has not been inserted\n"; }
Returns true, or throws an exception on error.
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The requires table was originally created with the following \s-1SQL\s0 command.
CREATE TABLE requires ( distribution TEXT NOT NULL, module TEXT NOT NULL, version TEXT NULL, phase TEXT NOT NULL, PRIMARY KEY (distribution, module, phase), FOREIGN KEY (distribution) REFERENCES distribution (distribution), FOREIGN KEY (module) REFERENCES module (module) )
CPANDB::Requires is part of the \s-1CPANDB\s0 \s-1API\s0.
See the documentation for \s-1CPANDB\s0 for more information.
Adam Kennedy <[email protected]>
Copyright 2009 - 2012 Adam Kennedy.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
The full text of the license can be found in the \s-1LICENSE\s0 file included with this module.