taiga代码研究--base--装饰器

 

 

# -*- coding: utf-8 -*-
# Copyright (C) 2014-2016 Andrey Antukh <niwi@niwi.nz>
# Copyright (C) 2014-2016 Jesús Espino <jespinog@gmail.com>
# Copyright (C) 2014-2016 David Barragán <bameda@dbarragan.com>
# Copyright (C) 2014-2016 Alejandro Alonso <alejandro.alonso@kaleidos.net>
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

from django_pglocks import advisory_lock


def detail_route(methods=['get'], **kwargs):
    """
    Used to mark a method on a ViewSet that should be routed for detail requests.
    """
    def decorator(func):
        func.bind_to_methods = methods
        func.detail = True
        func.permission_classes = kwargs.get('permission_classes', [])
        func.kwargs = kwargs
        return func
    return decorator


def list_route(methods=['get'], **kwargs):
    """
    Used to mark a method on a ViewSet that should be routed for list requests.
    """
    def decorator(func):
        func.bind_to_methods = methods
        func.detail = False
        func.permission_classes = kwargs.get('permission_classes', [])
        func.kwargs = kwargs
        return func
    return decorator


def model_pk_lock(func):
    """
    This decorator is designed to be used in ModelViewsets methods to lock them based
    on the model and the id of the selected object.
    """
    def decorator(self, *args, **kwargs):
        from taiga.base.utils.db import get_typename_for_model_class
        pk = self.kwargs.get(self.pk_url_kwarg, None)
        tn = get_typename_for_model_class(self.get_queryset().model)
        key = "{0}:{1}".format(tn, pk)

        with advisory_lock(key):
            return func(self, *args, **kwargs)

    return decorator

 

 

 

调用举例:   更新数据库前的检查

 @tx.atomic
 @model_pk_lock

 def update(self, request, *args, **kwargs):
    partial = kwargs.pop('partial', False)
    self.object = self.get_object_or_none()
    self.check_permissions(request, 'update', self.object)

    if self.object is None:
        raise Http404

    validator = self.get_validator(self.object, data=request.DATA,
                                   files=request.FILES, partial=partial)

    if not validator.is_valid():
        return response.BadRequest(validator.errors)

    # Hooks
    try:
        self.pre_save(validator.object)
        self.pre_conditions_on_save(validator.object)
    except ValidationError as err:
        # full_clean on model instance may be called in pre_save,
        # so we have to handle eventual errors.
        return response.BadRequest(err.message_dict)

    if self.object is None:
        self.object = validator.save(force_insert=True)
        self.post_save(self.object, created=True)
        instance = self.get_queryset().get(id=self.object.id)
        serializer = self.get_serializer(instance)
        return response.Created(serializer.data)

    self.object = validator.save(force_update=True)
    self.post_save(self.object, created=False)
    instance = self.get_queryset().get(id=self.object.id)
    serializer = self.get_serializer(instance)
    return response.Ok(serializer.data)

 

其中 

try:
    self.pre_save(validator.object)
    self.pre_conditions_on_save(validator.object)