Method reload

mongoengine/document.py:762–811

Reloads all attributes from the database. :param fields: (optional) args list of fields to reload :param max_depth: (optional) depth of dereferencing to follow

(self, *fields, **kwargs)

        return self

    def reload(self, *fields, **kwargs):
        """Reloads all attributes from the database.

        :param fields: (optional) args list of fields to reload
        :param max_depth: (optional) depth of dereferencing to follow
        """
        max_depth = 1
        if fields and isinstance(fields[0], int):
            max_depth = fields[0]
            fields = fields[1:]
        elif "max_depth" in kwargs:
            max_depth = kwargs["max_depth"]

        if self.pk is None:
            raise self.DoesNotExist("Document does not exist")

        obj = (
            self._qs.read_preference(ReadPreference.PRIMARY)
            .filter(**self._object_key)
            .only(*fields)
            .limit(1)
            .select_related(max_depth=max_depth)
        )

        if obj:
            obj = obj[0]
        else:
            raise self.DoesNotExist("Document does not exist")
        for field in obj._data:
            if not fields or field in fields:
                try:
                    setattr(self, field, self._reload(field, obj[field]))
                except (KeyError, AttributeError):
                    try:
                        # If field is a special field, e.g. items is stored as _reserved_items,
                        # a KeyError is thrown. So try to retrieve the field from _data
                        setattr(self, field, self._reload(field, obj._data.get(field)))
                    except KeyError:
                        # If field is removed from the database while the object
                        # is in memory, a reload would cause a KeyError
                        # i.e. obj.update(unset__field=1) followed by obj.reload()
                        delattr(self, field)

        self._changed_fields = (
            list(set(self._changed_fields) - set(fields))
            if fields
            else obj._changed_fields
        )
        self._created = False
        return self

    def _reload(self, key, value):
        """Used by :meth:`~mongoengine.Document.reload` to ensure the