69 lines
2.2 KiB
Python
69 lines
2.2 KiB
Python
import pymongo
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import fields
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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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doc_fields = {}
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# Include all fields present in superclasses
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for base in bases:
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if hasattr(base, '_fields'):
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doc_fields.update(base._fields)
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# Add the document's fields to the _fields attribute
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for attr_name, attr_val in attrs.items():
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if issubclass(attr_val.__class__, fields.Field):
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if not attr_val.name:
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attr_val.name = attr_name
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doc_fields[attr_name] = attr_val
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attrs['_fields'] = doc_fields
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return type.__new__(cls, name, bases, attrs)
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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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# Classes defined in this module are abstract and should not have
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# their own metadata with DB collection, etc.
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if attrs['__module__'] != __name__:
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collection = name.lower()
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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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meta = {
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'collection': collection,
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}
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meta.update(attrs.get('meta', {}))
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attrs['_meta'] = meta
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return DocumentMetaclass.__new__(cls, name, bases, attrs)
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class Document(object):
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__metaclass__ = TopLevelDocumentMetaclass
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def __init__(self, **values):
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self._data = {}
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# Assign initial values to instance
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for attr_name, attr_value in self._fields.items():
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if attr_name in values:
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setattr(self, attr_name, values.pop(attr_name))
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else:
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# Use default value
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setattr(self, attr_name, getattr(self, attr_name))
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def __iter__(self):
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# Use _data rather than _fields as iterator only looks at names so
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# values don't need to be converted to Python types
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return iter(self._data)
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