86233bcdf5
The current implementation is still very basic and needs some polish. The essence of it is that each Document gets a new meta attribute called "delete_rules" that is a dictionary containing (documentclass, fieldname) as key and the actual delete rule as a value. (Possible values are DO_NOTHING, NULLIFY, CASCADE and DENY. Of those, only CASCADE is currently implented.)
503 lines
18 KiB
Python
503 lines
18 KiB
Python
from queryset import QuerySet, QuerySetManager
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from queryset import DoesNotExist, MultipleObjectsReturned
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import sys
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import pymongo
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import pymongo.objectid
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_document_registry = {}
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def get_document(name):
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return _document_registry[name]
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class ValidationError(Exception):
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pass
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class BaseField(object):
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"""A base class for fields in a MongoDB document. Instances of this class
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may be added to subclasses of `Document` to define a document's schema.
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"""
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# Fields may have _types inserted into indexes by default
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_index_with_types = True
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_geo_index = False
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def __init__(self, db_field=None, name=None, required=False, default=None,
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unique=False, unique_with=None, primary_key=False,
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validation=None, choices=None):
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self.db_field = (db_field or name) if not primary_key else '_id'
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if name:
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import warnings
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msg = "Fields' 'name' attribute deprecated in favour of 'db_field'"
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warnings.warn(msg, DeprecationWarning)
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self.name = None
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self.required = required or primary_key
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self.default = default
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self.unique = bool(unique or unique_with)
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self.unique_with = unique_with
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self.primary_key = primary_key
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self.validation = validation
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self.choices = choices
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def __get__(self, instance, owner):
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"""Descriptor for retrieving a value from a field in a document. Do
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any necessary conversion between Python and MongoDB types.
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"""
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if instance is None:
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# Document class being used rather than a document object
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return self
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# Get value from document instance if available, if not use default
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value = instance._data.get(self.name)
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if value is None:
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value = self.default
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# Allow callable default values
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if callable(value):
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value = value()
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return value
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def __set__(self, instance, value):
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"""Descriptor for assigning a value to a field in a document.
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"""
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instance._data[self.name] = value
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def to_python(self, value):
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"""Convert a MongoDB-compatible type to a Python type.
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"""
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return value
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def to_mongo(self, value):
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"""Convert a Python type to a MongoDB-compatible type.
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"""
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return self.to_python(value)
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def prepare_query_value(self, op, value):
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"""Prepare a value that is being used in a query for PyMongo.
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"""
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return value
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def validate(self, value):
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"""Perform validation on a value.
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"""
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pass
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def _validate(self, value):
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# check choices
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if self.choices is not None:
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if value not in self.choices:
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raise ValidationError("Value must be one of %s."
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% unicode(self.choices))
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# check validation argument
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if self.validation is not None:
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if callable(self.validation):
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if not self.validation(value):
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raise ValidationError('Value does not match custom' \
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'validation method.')
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else:
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raise ValueError('validation argument must be a callable.')
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self.validate(value)
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class ObjectIdField(BaseField):
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"""An field wrapper around MongoDB's ObjectIds.
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"""
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def to_python(self, value):
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return value
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# return unicode(value)
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def to_mongo(self, value):
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if not isinstance(value, pymongo.objectid.ObjectId):
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try:
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return pymongo.objectid.ObjectId(unicode(value))
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except Exception, e:
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#e.message attribute has been deprecated since Python 2.6
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raise ValidationError(unicode(e))
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return value
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def prepare_query_value(self, op, value):
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return self.to_mongo(value)
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def validate(self, value):
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try:
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pymongo.objectid.ObjectId(unicode(value))
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except:
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raise ValidationError('Invalid Object ID')
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class DocumentMetaclass(type):
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"""Metaclass for all documents.
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"""
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def __new__(cls, name, bases, attrs):
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metaclass = attrs.get('__metaclass__')
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super_new = super(DocumentMetaclass, cls).__new__
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if metaclass and issubclass(metaclass, DocumentMetaclass):
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return super_new(cls, name, bases, attrs)
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doc_fields = {}
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class_name = [name]
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superclasses = {}
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simple_class = True
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for base in bases:
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# Include all fields present in superclasses
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if hasattr(base, '_fields'):
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doc_fields.update(base._fields)
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class_name.append(base._class_name)
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# Get superclasses from superclass
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superclasses[base._class_name] = base
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superclasses.update(base._superclasses)
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if hasattr(base, '_meta'):
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# Ensure that the Document class may be subclassed -
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# inheritance may be disabled to remove dependency on
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# additional fields _cls and _types
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if base._meta.get('allow_inheritance', True) == False:
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raise ValueError('Document %s may not be subclassed' %
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base.__name__)
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else:
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simple_class = False
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meta = attrs.get('_meta', attrs.get('meta', {}))
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if 'allow_inheritance' not in meta:
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meta['allow_inheritance'] = True
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# Only simple classes - direct subclasses of Document - may set
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# allow_inheritance to False
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if not simple_class and not meta['allow_inheritance']:
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raise ValueError('Only direct subclasses of Document may set '
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'"allow_inheritance" to False')
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attrs['_meta'] = meta
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attrs['_class_name'] = '.'.join(reversed(class_name))
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attrs['_superclasses'] = superclasses
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# Add the document's fields to the _fields attribute
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for attr_name, attr_value in attrs.items():
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if hasattr(attr_value, "__class__") and \
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issubclass(attr_value.__class__, BaseField):
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attr_value.name = attr_name
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if not attr_value.db_field:
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attr_value.db_field = attr_name
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doc_fields[attr_name] = attr_value
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attrs['_fields'] = doc_fields
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new_class = super_new(cls, name, bases, attrs)
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for field in new_class._fields.values():
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field.owner_document = new_class
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if hasattr(field, 'delete_rule') and field.delete_rule:
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field.document_type._meta['delete_rules'][(new_class, field.name)] = field.delete_rule
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module = attrs.get('__module__')
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base_excs = tuple(base.DoesNotExist for base in bases
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if hasattr(base, 'DoesNotExist')) or (DoesNotExist,)
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exc = subclass_exception('DoesNotExist', base_excs, module)
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new_class.add_to_class('DoesNotExist', exc)
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base_excs = tuple(base.MultipleObjectsReturned for base in bases
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if hasattr(base, 'MultipleObjectsReturned'))
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base_excs = base_excs or (MultipleObjectsReturned,)
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exc = subclass_exception('MultipleObjectsReturned', base_excs, module)
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new_class.add_to_class('MultipleObjectsReturned', exc)
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global _document_registry
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_document_registry[name] = new_class
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return new_class
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def add_to_class(self, name, value):
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setattr(self, name, value)
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class TopLevelDocumentMetaclass(DocumentMetaclass):
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"""Metaclass for top-level documents (i.e. documents that have their own
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collection in the database.
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"""
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def __new__(cls, name, bases, attrs):
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super_new = super(TopLevelDocumentMetaclass, cls).__new__
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# Classes defined in this package are abstract and should not have
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# their own metadata with DB collection, etc.
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# __metaclass__ is only set on the class with the __metaclass__
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# attribute (i.e. it is not set on subclasses). This differentiates
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# 'real' documents from the 'Document' class
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if attrs.get('__metaclass__') == TopLevelDocumentMetaclass:
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return super_new(cls, name, bases, attrs)
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collection = name.lower()
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id_field = None
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base_indexes = []
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base_meta = {}
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# Subclassed documents inherit collection from superclass
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for base in bases:
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if hasattr(base, '_meta') and 'collection' in base._meta:
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collection = base._meta['collection']
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# Propagate index options.
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for key in ('index_background', 'index_drop_dups', 'index_opts'):
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if key in base._meta:
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base_meta[key] = base._meta[key]
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id_field = id_field or base._meta.get('id_field')
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base_indexes += base._meta.get('indexes', [])
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meta = {
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'collection': collection,
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'max_documents': None,
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'max_size': None,
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'ordering': [], # default ordering applied at runtime
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'indexes': [], # indexes to be ensured at runtime
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'id_field': id_field,
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'index_background': False,
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'index_drop_dups': False,
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'index_opts': {},
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'queryset_class': QuerySet,
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'delete_rules': {},
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}
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meta.update(base_meta)
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# Apply document-defined meta options
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meta.update(attrs.get('meta', {}))
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attrs['_meta'] = meta
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# Set up collection manager, needs the class to have fields so use
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# DocumentMetaclass before instantiating CollectionManager object
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new_class = super_new(cls, name, bases, attrs)
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# Provide a default queryset unless one has been manually provided
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if not hasattr(new_class, 'objects'):
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new_class.objects = QuerySetManager()
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user_indexes = [QuerySet._build_index_spec(new_class, spec)
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for spec in meta['indexes']] + base_indexes
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new_class._meta['indexes'] = user_indexes
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unique_indexes = []
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for field_name, field in new_class._fields.items():
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# Generate a list of indexes needed by uniqueness constraints
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if field.unique:
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field.required = True
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unique_fields = [field.db_field]
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# Add any unique_with fields to the back of the index spec
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if field.unique_with:
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if isinstance(field.unique_with, basestring):
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field.unique_with = [field.unique_with]
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# Convert unique_with field names to real field names
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unique_with = []
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for other_name in field.unique_with:
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parts = other_name.split('.')
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# Lookup real name
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parts = QuerySet._lookup_field(new_class, parts)
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name_parts = [part.db_field for part in parts]
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unique_with.append('.'.join(name_parts))
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# Unique field should be required
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parts[-1].required = True
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unique_fields += unique_with
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# Add the new index to the list
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index = [(f, pymongo.ASCENDING) for f in unique_fields]
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unique_indexes.append(index)
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# Check for custom primary key
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if field.primary_key:
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current_pk = new_class._meta['id_field']
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if current_pk and current_pk != field_name:
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raise ValueError('Cannot override primary key field')
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if not current_pk:
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new_class._meta['id_field'] = field_name
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# Make 'Document.id' an alias to the real primary key field
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new_class.id = field
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new_class._meta['unique_indexes'] = unique_indexes
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if not new_class._meta['id_field']:
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new_class._meta['id_field'] = 'id'
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new_class._fields['id'] = ObjectIdField(db_field='_id')
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new_class.id = new_class._fields['id']
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return new_class
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class BaseDocument(object):
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def __init__(self, **values):
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self._data = {}
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# Assign default values to instance
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for attr_name in self._fields.keys():
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# Use default value if present
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value = getattr(self, attr_name, None)
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setattr(self, attr_name, value)
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# Assign initial values to instance
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for attr_name in values.keys():
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try:
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setattr(self, attr_name, values.pop(attr_name))
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except AttributeError:
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pass
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def validate(self):
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"""Ensure that all fields' values are valid and that required fields
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are present.
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"""
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# Get a list of tuples of field names and their current values
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fields = [(field, getattr(self, name))
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for name, field in self._fields.items()]
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# Ensure that each field is matched to a valid value
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for field, value in fields:
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if value is not None:
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try:
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field._validate(value)
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except (ValueError, AttributeError, AssertionError), e:
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raise ValidationError('Invalid value for field of type "%s": %s'
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% (field.__class__.__name__, value))
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elif field.required:
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raise ValidationError('Field "%s" is required' % field.name)
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@classmethod
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def _get_subclasses(cls):
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"""Return a dictionary of all subclasses (found recursively).
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"""
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try:
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subclasses = cls.__subclasses__()
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except:
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subclasses = cls.__subclasses__(cls)
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all_subclasses = {}
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for subclass in subclasses:
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all_subclasses[subclass._class_name] = subclass
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all_subclasses.update(subclass._get_subclasses())
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return all_subclasses
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@apply
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def pk():
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"""Primary key alias
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"""
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def fget(self):
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return getattr(self, self._meta['id_field'])
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def fset(self, value):
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return setattr(self, self._meta['id_field'], value)
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return property(fget, fset)
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def __iter__(self):
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return iter(self._fields)
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def __getitem__(self, name):
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"""Dictionary-style field access, return a field's value if present.
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"""
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try:
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if name in self._fields:
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return getattr(self, name)
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except AttributeError:
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pass
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raise KeyError(name)
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def __setitem__(self, name, value):
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"""Dictionary-style field access, set a field's value.
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"""
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# Ensure that the field exists before settings its value
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if name not in self._fields:
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raise KeyError(name)
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return setattr(self, name, value)
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def __contains__(self, name):
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try:
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val = getattr(self, name)
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return val is not None
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except AttributeError:
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return False
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def __len__(self):
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return len(self._data)
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def __repr__(self):
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try:
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u = unicode(self)
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except (UnicodeEncodeError, UnicodeDecodeError):
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u = '[Bad Unicode data]'
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return u'<%s: %s>' % (self.__class__.__name__, u)
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def __str__(self):
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if hasattr(self, '__unicode__'):
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return unicode(self).encode('utf-8')
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return '%s object' % self.__class__.__name__
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def to_mongo(self):
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"""Return data dictionary ready for use with MongoDB.
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"""
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data = {}
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for field_name, field in self._fields.items():
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value = getattr(self, field_name, None)
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if value is not None:
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data[field.db_field] = field.to_mongo(value)
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# Only add _cls and _types if allow_inheritance is not False
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if not (hasattr(self, '_meta') and
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self._meta.get('allow_inheritance', True) == False):
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data['_cls'] = self._class_name
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data['_types'] = self._superclasses.keys() + [self._class_name]
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if data.has_key('_id') and not data['_id']:
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del data['_id']
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return data
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@classmethod
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def _from_son(cls, son):
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"""Create an instance of a Document (subclass) from a PyMongo SON.
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"""
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# get the class name from the document, falling back to the given
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# class if unavailable
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class_name = son.get(u'_cls', cls._class_name)
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data = dict((str(key), value) for key, value in son.items())
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if '_types' in data:
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del data['_types']
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if '_cls' in data:
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del data['_cls']
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# Return correct subclass for document type
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if class_name != cls._class_name:
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subclasses = cls._get_subclasses()
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if class_name not in subclasses:
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# Type of document is probably more generic than the class
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# that has been queried to return this SON
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return None
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cls = subclasses[class_name]
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present_fields = data.keys()
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for field_name, field in cls._fields.items():
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if field.db_field in data:
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value = data[field.db_field]
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data[field_name] = (value if value is None
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else field.to_python(value))
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obj = cls(**data)
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obj._present_fields = present_fields
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return obj
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def __eq__(self, other):
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if isinstance(other, self.__class__) and hasattr(other, 'id'):
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if self.id == other.id:
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return True
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return False
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if sys.version_info < (2, 5):
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# Prior to Python 2.5, Exception was an old-style class
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def subclass_exception(name, parents, unused):
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import types
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return types.ClassType(name, parents, {})
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else:
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def subclass_exception(name, parents, module):
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return type(name, parents, {'__module__': module})
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