l.s.d.d.DecoratedResultSet(object) : class documentation

Part of lp.services.database.decoratedresultset View In Hierarchy

A decorated Storm ResultSet for 'Magic' (presenter) classes.

Because DistroSeriesBinaryPackage doesn't actually exist in the database, the DistroSeries.searchPackages method uses the DistroSeriesPackageCache object to search for packages within a DistroSeries.

Nonetheless, the users of the searchPackages method (such as the DistroSeriesView) expect a result set of DSBPs. Rather than executing the query prematurely and doing a list comprehension on the complete result set (which could be very large) to convert all the results (even though batching may mean only a window of 10 results is required), this adapted result set converts the results only when they are needed.

This behaviour is required for other classes as well (Distribution, DistroArchSeries), hence a generalised solution.

Method	__init__	Wrap `result_set` in a decorator.
Method	decorate_single	Decorate a result or return None if the result is itself None
Method	copy	See `IResultSet`.
Method	config	See `IResultSet`.
Method	__iter__	See `IResultSet`.
Method	__getitem__	See `IResultSet`.
Method	iterhook_one_elem	Undocumented
Method	any	See `IResultSet`.
Method	first	See `IResultSet`.
Method	last	See `IResultSet`.
Method	one	See `IResultSet`.
Method	order_by	See `IResultSet`.
Method	get_plain_result_set	Return the plain Storm result set.
Method	find	See `IResultSet`.
Method	_extract_plain_and_result	Extract the plain and normal results from a sub-result.

def __init__(self, result_set, result_decorator=None, pre_iter_hook=None, bulk_decorator=None, slice_info=False, return_both=False):

Wrap result_set in a decorator.

The decorator will act as a result set where a result row self[x] is really result_decorator(result_set[x]).

Parameters	result_set	The original result set to be decorated.
	result_decorator	A transformation function that individual results will be passed through. Mutually exclusive with bulk_decorator.
	pre_iter_hook	The method to be called (with the 'result_set') immediately before iteration starts. The return value of the hook is ignored.
	bulk_decorator	A transformation function that chunks of results will be passed through. Mutually exclusive with result_decorator.
	slice_info	If True pass information about the slice parameters to the result_decorator and pre_iter_hook. any() and similar methods will cause None to be supplied.
	return_both	If True return both the plain and decorated values as a tuple.

def _extract_plain_and_result(self, results):

Extract the plain and normal results from a sub-result.

This gets slightly complicated when there are nested DecoratedResultSets, as we have to propogate the plain result all the way up.

def decorate_single(self, result, row_index=None):

Decorate a result or return None if the result is itself None

def copy(self, *args, **kwargs):

See IResultSet.

Returns The decorated version of the returned result set.

def config(self, *args, **kwargs):

See IResultSet.

Returns The decorated result set.after updating the config.

def __iter__(self, *args, **kwargs):

See IResultSet.

Yield a decorated version of the returned value.

def __getitem__(self, *args, **kwargs):

See IResultSet.