Source code for couchbase_core.items

# Copyright 2013, Couchbase, Inc.
# All Rights Reserved
# Licensed under the Apache License, Version 2.0 (the "License")
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.

# This module contains various collections to be used with items. These provide
# various means by which multiple operations can have their options customized

# Each of these collections yields an iterator consisting of a 3-tuple:
# (item, {options})
# The CAS, Format, and Value are all expected to be inside the Item itself;

from couchbase_core._libcouchbase import Item as _Item

[docs]class Item(_Item): def __init__(self, key=None, value=None): """ Construct a new `Item` object. :param string key: The key to initialize this item with :param object value: The value to initialize this item with The `Item` class is a sublcass of a :class:`~couchbase_core.result.ValueResult`. Its members are all writeable and accessible from this object. .. warning:: As the item build-in properties (such as ``key``, ``value``, ``cas``, etc.) are implemented directly in C and are not exposed in the item's ``__dict__`` field, you cannot override these fields in a subclass to be a ``property`` or some other custom data descriptor. To confuse matters even more, if you do implement these properties as descriptors, they will be visible from your own code, but *not* from the implementation code. You have been warned. In short, don't override these properties. Here's an example of what you should *not* do:: class MyItem(Item): # ... @property def key(self): return self._key @key.setter def key(self, newkey): self._key = key To use this class with the :class:`couchbase_core.client.Client` API methods, you must take care to: 1. Use only the ``*_multi`` methods 2. Pass one of the :class:`ItemCollection` objects to these methods. This will let the API know to enable special handling for the :class:`Item` API. """ super(Item, self).__init__() self.key = key self.value = value
[docs] def as_itcoll(self, **kwargs): """ Convenience method to return an instance of a :class:`ItemCollection` containing only this item. This would then be used like so:: cb.upsert_multi(itm.as_itcoll()) Or use it with options:: cb.upsert_multi(itm.as_itcoll(ignore_cas=True)) :param kwargs: Extra operation-specific options. :return: An :class:`ItemCollection` instance """ if not kwargs: return ItemSequence([self]) else: return ItemOptionDict({self: kwargs})
[docs]class ItemCollection(object): """ The base class for a collection of Items. """ def __len__(self): raise NotImplementedError() def __iter__(self): """ This iterator is mainly intended for the internal API use; it yields a tuple of (item, options). In the case of a :class:`ItemSequence` which does not store options, the second element is always `None` """ def dict_items(self): """ Iterator which returns a tuple of ``(item, options)`` for each item in this collection. """ return iter(self)
[docs]class ItemOptionDict(ItemCollection): def __init__(self, d=None): """ A simple mapping of :class:`Item` objects to optional dictionaries of values. The keys and values for the options dictionary depends on the command being used. See the appropriate command for more options :param dict d: A dictionary of item -> option, or None. """ if d is None: d = {} self._d = d @property def dict(self): """ Return the actual dict object """ return self._d
[docs] def add(self, itm, **options): """ Convenience method to add an item together with a series of options. :param itm: The item to add :param options: keyword arguments which will be placed in the item's option entry. If the item already exists, it (and its options) will be overidden. Use :attr:`dict` instead to update options """ if not options: options = None self._d[itm] = options
[docs] def create_and_add(self, key, value=None, cas=0, **options): """ Creates and adds an item. :param key: The key to use for the item :param value: The value to use for the item :param options: Additional operation-specific options """ itm = Item(key, value) itm.cas = cas return self.add(itm, **options)
def __iter__(self): for p in self._d.items(): yield p def __len__(self): return len(self._d)
[docs]class ItemSequence(ItemCollection): def __init__(self, obj): """ Create a new :class:`ItemSequence` object :param seq: A sequence containing the items :type seq: An iterable or a single item """ self._seq = [obj] if isinstance(obj, Item) else obj # Verify this is indeed a sequence len(self._seq) @property def sequence(self): """ The actual sequence object passed in """ return self._seq def __len__(self): return len(self._seq) def __iter__(self): for e in self._seq: yield (e, None)