/usr/lib/python3/dist-packages/mongoengine/base/metaclasses.py is in python3-mongoengine 0.10.6-1.
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from mongoengine.common import _import_class
from mongoengine.errors import InvalidDocumentError
from mongoengine.python_support import PY3
from mongoengine.queryset import (DO_NOTHING, DoesNotExist,
MultipleObjectsReturned,
QuerySetManager)
from mongoengine.base.common import _document_registry, ALLOW_INHERITANCE
from mongoengine.base.fields import BaseField, ComplexBaseField, ObjectIdField
import collections
__all__ = ('DocumentMetaclass', 'TopLevelDocumentMetaclass')
class DocumentMetaclass(type):
"""Metaclass for all documents.
"""
def __new__(cls, name, bases, attrs):
flattened_bases = cls._get_bases(bases)
super_new = super(DocumentMetaclass, cls).__new__
# If a base class just call super
metaclass = attrs.get('my_metaclass')
if metaclass and issubclass(metaclass, DocumentMetaclass):
return super_new(cls, name, bases, attrs)
attrs['_is_document'] = attrs.get('_is_document', False)
attrs['_cached_reference_fields'] = []
# EmbeddedDocuments could have meta data for inheritance
if 'meta' in attrs:
attrs['_meta'] = attrs.pop('meta')
# EmbeddedDocuments should inherit meta data
if '_meta' not in attrs:
meta = MetaDict()
for base in flattened_bases[::-1]:
# Add any mixin metadata from plain objects
if hasattr(base, 'meta'):
meta.merge(base.meta)
elif hasattr(base, '_meta'):
meta.merge(base._meta)
attrs['_meta'] = meta
attrs['_meta']['abstract'] = False # 789: EmbeddedDocument shouldn't inherit abstract
if attrs['_meta'].get('allow_inheritance', ALLOW_INHERITANCE):
StringField = _import_class('StringField')
attrs['_cls'] = StringField()
# Handle document Fields
# Merge all fields from subclasses
doc_fields = {}
for base in flattened_bases[::-1]:
if hasattr(base, '_fields'):
doc_fields.update(base._fields)
# Standard object mixin - merge in any Fields
if not hasattr(base, '_meta'):
base_fields = {}
for attr_name, attr_value in base.__dict__.items():
if not isinstance(attr_value, BaseField):
continue
attr_value.name = attr_name
if not attr_value.db_field:
attr_value.db_field = attr_name
base_fields[attr_name] = attr_value
doc_fields.update(base_fields)
# Discover any document fields
field_names = {}
for attr_name, attr_value in attrs.items():
if not isinstance(attr_value, BaseField):
continue
attr_value.name = attr_name
if not attr_value.db_field:
attr_value.db_field = attr_name
doc_fields[attr_name] = attr_value
# Count names to ensure no db_field redefinitions
field_names[attr_value.db_field] = field_names.get(
attr_value.db_field, 0) + 1
# Ensure no duplicate db_fields
duplicate_db_fields = [k for k, v in list(field_names.items()) if v > 1]
if duplicate_db_fields:
msg = ("Multiple db_fields defined for: %s " %
", ".join(duplicate_db_fields))
raise InvalidDocumentError(msg)
# Set _fields and db_field maps
attrs['_fields'] = doc_fields
attrs['_db_field_map'] = dict([(k, getattr(v, 'db_field', k))
for k, v in doc_fields.items()])
attrs['_reverse_db_field_map'] = dict(
(v, k) for k, v in attrs['_db_field_map'].items())
attrs['_fields_ordered'] = tuple(i[1] for i in sorted(
(v.creation_counter, v.name)
for v in doc_fields.values()))
#
# Set document hierarchy
#
superclasses = ()
class_name = [name]
for base in flattened_bases:
if (not getattr(base, '_is_base_cls', True) and
not getattr(base, '_meta', {}).get('abstract', True)):
# Collate hierarchy for _cls and _subclasses
class_name.append(base.__name__)
if hasattr(base, '_meta'):
# Warn if allow_inheritance isn't set and prevent
# inheritance of classes where inheritance is set to False
allow_inheritance = base._meta.get('allow_inheritance',
ALLOW_INHERITANCE)
if (allow_inheritance is not True and
not base._meta.get('abstract')):
raise ValueError('Document %s may not be subclassed' %
base.__name__)
# Get superclasses from last base superclass
document_bases = [b for b in flattened_bases
if hasattr(b, '_class_name')]
if document_bases:
superclasses = document_bases[0]._superclasses
superclasses += (document_bases[0]._class_name, )
_cls = '.'.join(reversed(class_name))
attrs['_class_name'] = _cls
attrs['_superclasses'] = superclasses
attrs['_subclasses'] = (_cls, )
attrs['_types'] = attrs['_subclasses'] # TODO depreciate _types
# Create the new_class
new_class = super_new(cls, name, bases, attrs)
# Set _subclasses
for base in document_bases:
if _cls not in base._subclasses:
base._subclasses += (_cls,)
base._types = base._subclasses # TODO depreciate _types
(Document, EmbeddedDocument, DictField,
CachedReferenceField) = cls._import_classes()
if issubclass(new_class, Document):
new_class._collection = None
# Add class to the _document_registry
_document_registry[new_class._class_name] = new_class
# In Python 2, User-defined methods objects have special read-only
# attributes 'im_func' and 'im_self' which contain the function obj
# and class instance object respectively. With Python 3 these special
# attributes have been replaced by __func__ and __self__. The Blinker
# module continues to use im_func and im_self, so the code below
# copies __func__ into im_func and __self__ into im_self for
# classmethod objects in Document derived classes.
if PY3:
for key, val in list(new_class.__dict__.items()):
if isinstance(val, classmethod):
f = val.__get__(new_class)
if hasattr(f, '__func__') and not hasattr(f, 'im_func'):
f.__dict__.update({'im_func': getattr(f, '__func__')})
if hasattr(f, '__self__') and not hasattr(f, 'im_self'):
f.__dict__.update({'im_self': getattr(f, '__self__')})
# Handle delete rules
for field in new_class._fields.values():
f = field
if f.owner_document is None:
f.owner_document = new_class
delete_rule = getattr(f, 'reverse_delete_rule', DO_NOTHING)
if isinstance(f, CachedReferenceField):
if issubclass(new_class, EmbeddedDocument):
raise InvalidDocumentError(
"CachedReferenceFields is not allowed in EmbeddedDocuments")
if not f.document_type:
raise InvalidDocumentError(
"Document is not available to sync")
if f.auto_sync:
f.start_listener()
f.document_type._cached_reference_fields.append(f)
if isinstance(f, ComplexBaseField) and hasattr(f, 'field'):
delete_rule = getattr(f.field,
'reverse_delete_rule',
DO_NOTHING)
if isinstance(f, DictField) and delete_rule != DO_NOTHING:
msg = ("Reverse delete rules are not supported "
"for %s (field: %s)" %
(field.__class__.__name__, field.name))
raise InvalidDocumentError(msg)
f = field.field
if delete_rule != DO_NOTHING:
if issubclass(new_class, EmbeddedDocument):
msg = ("Reverse delete rules are not supported for "
"EmbeddedDocuments (field: %s)" % field.name)
raise InvalidDocumentError(msg)
f.document_type.register_delete_rule(new_class,
field.name, delete_rule)
if (field.name and hasattr(Document, field.name) and
EmbeddedDocument not in new_class.mro()):
msg = ("%s is a document method and not a valid "
"field name" % field.name)
raise InvalidDocumentError(msg)
return new_class
def add_to_class(self, name, value):
setattr(self, name, value)
@classmethod
def _get_bases(cls, bases):
if isinstance(bases, BasesTuple):
return bases
seen = []
bases = cls.__get_bases(bases)
unique_bases = (b for b in bases if not (b in seen or seen.append(b)))
return BasesTuple(unique_bases)
@classmethod
def __get_bases(cls, bases):
for base in bases:
if base is object:
continue
yield base
for child_base in cls.__get_bases(base.__bases__):
yield child_base
@classmethod
def _import_classes(cls):
Document = _import_class('Document')
EmbeddedDocument = _import_class('EmbeddedDocument')
DictField = _import_class('DictField')
CachedReferenceField = _import_class('CachedReferenceField')
return Document, EmbeddedDocument, DictField, CachedReferenceField
class TopLevelDocumentMetaclass(DocumentMetaclass):
"""Metaclass for top-level documents (i.e. documents that have their own
collection in the database.
"""
def __new__(cls, name, bases, attrs):
flattened_bases = cls._get_bases(bases)
super_new = super(TopLevelDocumentMetaclass, cls).__new__
# Set default _meta data if base class, otherwise get user defined meta
if attrs.get('my_metaclass') == TopLevelDocumentMetaclass:
# defaults
attrs['_meta'] = {
'abstract': True,
'max_documents': None,
'max_size': None,
'ordering': [], # default ordering applied at runtime
'indexes': [], # indexes to be ensured at runtime
'id_field': None,
'index_background': False,
'index_drop_dups': False,
'index_opts': None,
'delete_rules': None,
'allow_inheritance': None,
}
attrs['_is_base_cls'] = True
attrs['_meta'].update(attrs.get('meta', {}))
else:
attrs['_meta'] = attrs.get('meta', {})
# Explicitly set abstract to false unless set
attrs['_meta']['abstract'] = attrs['_meta'].get('abstract', False)
attrs['_is_base_cls'] = False
# Set flag marking as document class - as opposed to an object mixin
attrs['_is_document'] = True
# Ensure queryset_class is inherited
if 'objects' in attrs:
manager = attrs['objects']
if hasattr(manager, 'queryset_class'):
attrs['_meta']['queryset_class'] = manager.queryset_class
# Clean up top level meta
if 'meta' in attrs:
del attrs['meta']
# Find the parent document class
parent_doc_cls = [b for b in flattened_bases
if b.__class__ == TopLevelDocumentMetaclass]
parent_doc_cls = None if not parent_doc_cls else parent_doc_cls[0]
# Prevent classes setting collection different to their parents
# If parent wasn't an abstract class
if (parent_doc_cls and 'collection' in attrs.get('_meta', {}) and
not parent_doc_cls._meta.get('abstract', True)):
msg = "Trying to set a collection on a subclass (%s)" % name
warnings.warn(msg, SyntaxWarning)
del attrs['_meta']['collection']
# Ensure abstract documents have abstract bases
if attrs.get('_is_base_cls') or attrs['_meta'].get('abstract'):
if (parent_doc_cls and
not parent_doc_cls._meta.get('abstract', False)):
msg = "Abstract document cannot have non-abstract base"
raise ValueError(msg)
return super_new(cls, name, bases, attrs)
# Merge base class metas.
# Uses a special MetaDict that handles various merging rules
meta = MetaDict()
for base in flattened_bases[::-1]:
# Add any mixin metadata from plain objects
if hasattr(base, 'meta'):
meta.merge(base.meta)
elif hasattr(base, '_meta'):
meta.merge(base._meta)
# Set collection in the meta if its callable
if (getattr(base, '_is_document', False) and
not base._meta.get('abstract')):
collection = meta.get('collection', None)
if isinstance(collection, collections.Callable):
meta['collection'] = collection(base)
meta.merge(attrs.get('_meta', {})) # Top level meta
# Only simple classes (direct subclasses of Document)
# may set allow_inheritance to False
simple_class = all([b._meta.get('abstract')
for b in flattened_bases if hasattr(b, '_meta')])
if (not simple_class and meta['allow_inheritance'] is False and
not meta['abstract']):
raise ValueError('Only direct subclasses of Document may set '
'"allow_inheritance" to False')
# Set default collection name
if 'collection' not in meta:
meta['collection'] = ''.join('_%s' % c if c.isupper() else c
for c in name).strip('_').lower()
attrs['_meta'] = meta
# Call super and get the new class
new_class = super_new(cls, name, bases, attrs)
meta = new_class._meta
# Set index specifications
meta['index_specs'] = new_class._build_index_specs(meta['indexes'])
# If collection is a callable - call it and set the value
collection = meta.get('collection')
if isinstance(collection, collections.Callable):
new_class._meta['collection'] = collection(new_class)
# Provide a default queryset unless exists or one has been set
if 'objects' not in dir(new_class):
new_class.objects = QuerySetManager()
# Validate the fields and set primary key if needed
for field_name, field in new_class._fields.items():
if field.primary_key:
# Ensure only one primary key is set
current_pk = new_class._meta.get('id_field')
if current_pk and current_pk != field_name:
raise ValueError('Cannot override primary key field')
# Set primary key
if not current_pk:
new_class._meta['id_field'] = field_name
new_class.id = field
# Set primary key if not defined by the document
new_class._auto_id_field = getattr(parent_doc_cls,
'_auto_id_field', False)
if not new_class._meta.get('id_field'):
# After 0.10, find not existing names, instead of overwriting
id_name, id_db_name = cls.get_auto_id_names(new_class)
new_class._auto_id_field = True
new_class._meta['id_field'] = id_name
new_class._fields[id_name] = ObjectIdField(db_field=id_db_name)
new_class._fields[id_name].name = id_name
new_class.id = new_class._fields[id_name]
new_class._db_field_map[id_name] = id_db_name
new_class._reverse_db_field_map[id_db_name] = id_name
# Prepend id field to _fields_ordered
new_class._fields_ordered = (id_name, ) + new_class._fields_ordered
# Merge in exceptions with parent hierarchy
exceptions_to_merge = (DoesNotExist, MultipleObjectsReturned)
module = attrs.get('__module__')
for exc in exceptions_to_merge:
name = exc.__name__
parents = tuple(getattr(base, name) for base in flattened_bases
if hasattr(base, name)) or (exc,)
# Create new exception and set to new_class
exception = type(name, parents, {'__module__': module})
setattr(new_class, name, exception)
return new_class
@classmethod
def get_auto_id_names(cls, new_class):
id_name, id_db_name = ('id', '_id')
if id_name not in new_class._fields and \
id_db_name not in (v.db_field for v in list(new_class._fields.values())):
return id_name, id_db_name
id_basename, id_db_basename, i = 'auto_id', '_auto_id', 0
while id_name in new_class._fields or \
id_db_name in (v.db_field for v in list(new_class._fields.values())):
id_name = '{0}_{1}'.format(id_basename, i)
id_db_name = '{0}_{1}'.format(id_db_basename, i)
i += 1
return id_name, id_db_name
class MetaDict(dict):
"""Custom dictionary for meta classes.
Handles the merging of set indexes
"""
_merge_options = ('indexes',)
def merge(self, new_options):
for k, v in new_options.items():
if k in self._merge_options:
self[k] = self.get(k, []) + v
else:
self[k] = v
class BasesTuple(tuple):
"""Special class to handle introspection of bases tuple in __new__"""
pass
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