man Padre::DB::HostConfig (3): Padre::DB class for the host

DESCRIPTION

TO BE COMPLETED

METHODS

base

  # Returns 'Padre::DB'
  my $namespace = Padre::DB::HostConfig->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 "base" method.

table

  # Returns 'host_config'
  print Padre::DB::HostConfig->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 "table" method to get the table name.

load

  my $object = Padre::DB::HostConfig->load( $name );

If your table has single column primary key, a "load" method will be generated in the class. If there is no primary key, the method is not created.

The "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 "Padre::DB::HostConfig" object, or throws an exception if the object does not exist.

select

  # Get all objects in list context
  my @list = Padre::DB::HostConfig->select;
  
  # Get a subset of objects in scalar context
  my $array_ref = Padre::DB::HostConfig->select(
      'where name > ? order by name',
      1000,
  );

The "select" method executes a typical SQL "SELECT" query on the host_config table.

It takes an optional argument of a SQL phrase to be added after the "FROM host_config" 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 Padre::DB::HostConfig objects when called in list context, or a reference to an "ARRAY" of Padre::DB::HostConfig objects when called in scalar context.

Throws an exception on error, typically directly from the DBI layer.

iterate

  Padre::DB::HostConfig->iterate( sub {
      print $_->name . "\n";
  } );

The "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 "iterate" 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 "iterate" code fragment above functionally equivalent to the following, except with an O(1) memory cost instead of O(n).

  foreach ( Padre::DB::HostConfig->select ) {
      print $_->name . "\n";
  }

You can filter the list via SQL in the same way you can with "select".

  Padre::DB::HostConfig->iterate(
      'order by ?', 'name',
      sub {
          print $_->name . "\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 "ARRAY" references when used in this form.

  Padre::DB->iterate(
      'select name from host_config order by name',
      sub {
          print $_->[0] . "\n";
      }
  );

count

  # How many objects are in the table
  my $rows = Padre::DB::HostConfig->count;
  
  # How many objects 
  my $small = Padre::DB::HostConfig->count(
      'where name > ?',
      1000,
  );

The "count" method executes a "SELECT COUNT(*)" query on the host_config table.

Returns the number of objects that match the condition.

Throws an exception on error, typically directly from the DBI layer.

new

  TO BE COMPLETED

The "new" constructor is used to create a new abstract object that is not (yet) written to the database.

Returns a new Padre::DB::HostConfig object.

create

  my $object = Padre::DB::HostConfig->create(
      name => 'value',
      value => 'value',
  );

The "create" constructor is a one-step combination of "new" and "insert" that takes the column parameters, creates a new Padre::DB::HostConfig object, inserts the appropriate row into the host_config table, and then returns the object.

If the primary key column "name" is not provided to the constructor (or it is false) the object returned will have "name" set to the new unique identifier.

Returns a new host_config object, or throws an exception on error, typically from the DBI layer.

insert

  $object->insert;

The "insert" method commits a new object (created with the "new" method) into the database.

If a the primary key column "name" is not provided to the constructor (or it is false) the object returned will have "name" set to the new unique identifier.

Returns the object itself as a convenience, or throws an exception on error, typically from the DBI layer.

delete

  # Delete a single instantiated object
  $object->delete;
  
  # Delete multiple rows from the host_config table
  Padre::DB::HostConfig->delete('where name > ?', 1000);

The "delete" method can be used in a class form and an instance form.

When used on an existing Padre::DB::HostConfig instance, the "delete" method removes that specific instance from the "host_config", leaving the object intact for you to deal with post-delete actions as you wish.

When used as a class method, it takes a compulsory argument of a SQL phrase to be added after the "DELETE FROM host_config" 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 true on success or throws an exception on error, or if you attempt to call delete without a SQL condition phrase.

truncate

  # Delete all records in the host_config table
  Padre::DB::HostConfig->truncate;

To prevent the common and extremely dangerous error case where deletion is called accidentally without providing a condition, the use of the "delete" method without a specific condition is forbidden.

Instead, the distinct method "truncate" is provided to delete all records in a table with specific intent.

Returns true, or throws an exception on error.

ACCESSORS

name

  if ( $object->name ) {
      print "Object has been inserted\n";
  } else {
      print "Object has not been inserted\n";
  }

Returns true, or throws an exception on error.

REMAINING ACCESSORS TO BE COMPLETED

SQL

The host_config table was originally created with the following SQL command.

  CREATE TABLE host_config (
      name varchar(255) not null primary key,
      value varchar(255) not null
  )

SUPPORT

Padre::DB::HostConfig is part of the Padre::DB API.

See the documentation for Padre::DB for more information.

AUTHOR

Adam Kennedy <[email protected]>

COPYRIGHT

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 LICENSE file included with this module.