75 lines
2.1 KiB
Python
75 lines
2.1 KiB
Python
"""Representation of an ObjectId for Mongo."""
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import random
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import types
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from errors import InvalidId
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class ObjectId(object):
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"""A Mongo ObjectId.
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"""
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def __init__(self, id=None):
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"""Initialize a new ObjectId.
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If no value of id is given, create a new (unique) ObjectId. If given id
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is an instance of (string, ObjectId) validate it and use that.
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Otherwise, a TypeError is raised. If given an invalid id, InvalidId is
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raised.
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Arguments:
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- `id` (optional): a valid ObjectId
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"""
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if id is None:
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self.__generate()
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else:
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self.__validate(id)
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def __generate(self):
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"""Generate a new value for this ObjectId.
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"""
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# TODO for now, just generate 12 random bytes. this will change when we decide on an _id algorithm...
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self.__new = True
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oid = ""
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for _ in range(12):
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oid += chr(random.randint(0, 255))
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self.__id = oid
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def __validate(self, oid):
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"""Validate and use the given id for this ObjectId.
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Raises TypeError if id is not an instance of (str, ObjectId) and
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InvalidId if it is not a valid ObjectId.
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Arguments:
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- `id`: a valid ObjectId
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"""
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self.__new = False
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if isinstance(oid, ObjectId):
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self.__id = oid.__id
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elif isinstance(oid, types.StringType):
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if len(oid) == 12:
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self.__id = oid
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else:
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raise InvalidId("%s is not a valid ObjectId" % oid)
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else:
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raise TypeError("id must be an instance of (str, ObjectId), not %s" % type(oid))
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def __str__(self):
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return self.__id
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def __repr__(self):
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return "ObjectId(%r)" % self.__id
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def __cmp__(self, other):
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if isinstance(other, ObjectId):
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return cmp(self.__id, other.__id)
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return NotImplemented
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def _use(self):
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self.__new = False
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def is_new(self):
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"""Return True if this ObjectId has not been used as an _id field.
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"""
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return self.__new
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