README.rst

n_property

n + 1 = 2

用法1：

from n_property import n_class, n_property

@n_class
class Review(object):

    @n_property(fallback=None)
    def subject(selfs):
        subject_ids = [self.subject_id for self in selfs]
        return Subject.gets(subject_ids, filter_none=False)


reviews = Review.gets(review_ids)

print reviews[0].subject  # 第1次 Subject.gets 请求
print [r.subject for r in reviews]  # 触发批量prefetch，第2次 Subject.gets 请求

用法2 (more pythonic)：

from n_property import n_class, n_property

@n_class
class Review(object):
    subject = n_property(fallback=None)

    @subject.n_getter
    @classmethod
    def get_subjects(cls, insts):
        subject_ids = [inst.subject_id for inst in insts]
        return Subject.gets(subject_ids, filter_none=False)


reviews = Review.gets(review_ids)

print reviews[0].subject  # 第1次 Subject.gets 请求
print [r.subject for r in reviews]  # 触发批量prefetch，第2次 Subject.gets 请求