NAME

Persist::Source - Main class used for accessing Persist data

SYNOPSIS

  use Persist qw(:constants);
  use Persist::Source;

  $source = new Persist::Source(...);

  $source->new_table('folks', {
              folkid        => [ AUTONUMBER ],
              name          => [ VARCHAR, 20 ],
              age           => [ INTEGER ] }, [
              [ PRIMARY, [ 'folkid' ] ],
              [ UNIQUE, [ 'name' ] ] ]);

  $source->new_table('favorites', {
              favid         => [ AUTONUMER ],
              folkid        => [ INTEGER ],
              color         => [ VARCHAR, 20 ] }, [
              [ PRIMARY, [ 'favid' ] ],
              [ UNIQUE, [ 'folkid', 'color' ] ],
              [ LINK, [ 'folkid' ], 'folks', [ 'folkid' ] ] ]);

  $table = $source->folks;
  $join = $source->join([ 'folks', 'favorites' ]);
  $join2 = $source->explicit_join(
              [ O => 'folks', A => 'favorites' ]
			  "O.fid = A.fid");

DESCRIPTION

This abstraction is the core of the Persist framework. This provides an easy way to access persistent data.

$source = new Persist::Source($driver, @args)

This connects to a Persist data source using the driver named $driver. The @args argument is a special case to the mixed parameter passing syntax use by Persist. Instead of being a literal argument, @args is a set of named (not mixed) arguments that are passed directly to the drivers.

$test = $source->is_dba

Returns true if this object is permitted to use the create_source and delete_source methods.

@conn_args = $source->new_source(@args)

Creates a new persistent source and returns the arguments required to pass to the driver to access the new source. See driver documentation for the arguments required.

The @args list is a special case to the mixed argument syntax of Persist. These are required to be named arguments as they are passed directly on to the driver itself.

$source->delete_source(@args)

Deletes a persistent source. See driver documentation for the arguments required.

The @args list is a special case to the mixed argument syntax of Persist. These are required to be named arguments as they are passed directly on to the driver itself.

$source->new_table($table, \%columns, \@indexes)

Creates a new table in the persistent source. The $table is the name of the table to create. The %columns is a hash where the keys are the column names and the values are the types. The types are specified as an array reference with the first element being the type constant and the rest arguments to that type constant.

The @indexes is an array of array references to each index definition. The first element in an index definition is the index type constant and the rest are arguments to the index definition.

See Persist for information on type and index arguments.

$source->delete_table($table)

Delete the table naemd by $table.

@tables = $source->tables

Returns the names of all available tables in the database.

$join = $source->join($tables [, $filters ] )

Returns a reference to a Persist::Join object which may be used to access columns of the joined tables. $tables is a list of tables to join and $filters is a list of filters to apply to the tables, respectively.

This method tries to automatically join tables based upon their LINK indexes. This is process is done as intelligently as I could divine, but cannot join a table to itself--at least not currently. It will also use the first indexes it finds between two tables and will not use more than one index during a join. Finally, it will not look for links between tables that will result in a circular joining.

For more complicated joining, try explicit_join.

$join = $source->explicit_join($tables, $on_exprs [, $filter ])

This performs a more explicit form of the join operation. This allows the user to pick the fields joined upon in the case that there is no key constraint to guide the Persist system or when such implicit joins are otherwise inappropriate. The arguments to this method are a little more complicated than most, but should make sense:

$tables

This argument is an array reference with the appearance of a hash. There should be an even number of elements in the array. The even indexed attributes are table name aliases, which are followed by the odd attributes which are table names. This allows a table to be explicitly joined to itself. Here is an example,

[ O => 'Folks', A => 'Favorites' ]

For those that might not know, the arrow (=>) is equivalent to comma (,) except that it causes the preceding value to be stringified (i.e., interpreted as a string). (Wacky Perl syntactic sugar. ;)

$on_exprs

This is an array reference to a set of strings. There should be one expression for each join. Joins are performed in the order they are specified in $tables. The first two tables given will be joined first by the first expression in the first element of $on_exprs. The third table will be joined to the first two by the second element. The fourth table by the third element, etc. The expressions should use the table name aliases given in the $table argument.

If there's only one expression, i.e. only two tables in the join, you may omit the array reference and just include the expression as a string. If a full cross-product (unqualified join) is desired, then the undef value should be used in place of the expression. WARNING: A full cross-product join can be extremely inefficient in some contexts.

$filter (optional)

This string has the same purpose as the $filters argument to the other join method. However, this method is always a single string. This variable should also use the table name aliases given in the $table argument.

$table = $source->table($table [, $filter ])

Returns a reference to a Persist::Table object which may be used to access columns of the table.

$table = $source-><table>( [ $filter ] )

A shortcut to $source->table('<table>').

$source->delete($table [, $filter ])

Deletes all records matching the given filter.

WARNING: An undefined filter will delete all rows from the table.

Returns the number of rows deleted.

$source->insert($table, \%values)

Inserts a new row into the table named $table with the values given in \%values.

Returns 1 on success.

$rows = $source->update($table, \%set [, $filter ] )

Updates one or more rows in the table named $table. Only rows matching firlster will be updated and will be set to the values in %set.

WARNING: An undefined filter will update all rows.

Returns the number of rows altered.

SEE ALSO

Persist, Persist::Join, Persist::Driver, Persist::Table

AUTHOR

Andrew Sterling Hanenkamp, <hanenkamp@users.sourceforge.net>

COPYRIGHT AND LICENSE

Copyright (c) 2003, Andrew Sterling Hanenkamp
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