1. ORM的架构：

核心函数：new, all, find_all, find_by,find.get,update,remove
各个支持子函数及其功能：
核心函数的实现流程：

2. 代码实践

import time
from utils import log # 自定义的工具函数包
from pymongo import MongoClient
mongua = MongoClient() #默认是MongoClient("mongodb://localhost:27017")
# mongua是一个mongo的客户端实例，用它来操作数据库，数据库操作表，表操作记录def timestamp():return int(time.time())def next_id(name):query = {'name': name,}update = {'$inc': {'seq': 1}}kwargs = {'query': query,'update': update,'upsert': True, # 如果不存在某字段就创建'new': True,    # new为true：返回个性后的文档，false：返回个性前的，默认是false}# 存储数据的 iddoc = mongua.db['data_id'] #等价于创建了db这个数据库，以及data_id这个表# find_and_modify 是一个原子操作函数new_id = doc.find_and_modify(**kwargs).get('seq')return new_idclass Mongua(object):__fields__ = ['_id',# (字段名, 类型, 值)('id', int, -1),('type', str, ''),('deleted', bool, False),('created_time', int, 0),('updated_time', int, 0),]@classmethoddef has(cls, **kwargs):"""检查一个元素是否在数据库中 用法如下User.has(id=1):param kwargs::return:"""return cls.find_one(**kwargs) is not Nonedef mongos(self, name):return mongua.db[name]._find()def __repr__(self):class_name = self.__class__.__name__properties = ('{0} = {1}'.format(k, v) for k, v in self.__dict__.items())return '<{0}: \n  {1}\n>'.format(class_name, '\n  '.join(properties))@classmethoddef new(cls, form=None, **kwargs):"""new 是给外部使用的函数"""name = cls.__name__# 创建一个空对象m = cls()# 把定义的数据写入空对象, 未定义的数据输出错误fields = cls.__fields__.copy()# 去掉 _id 这个特殊的字段fields.remove('_id')if form is None:form = {}for f in fields:k, t, v = f # 取出fieldsif k in form:setattr(m, k, t(form[k])) # 用 form来覆盖默认值else:# 设置默认值setattr(m, k, v)# 处理额外的参数 kwargsfor k, v in kwargs.items():if hasattr(m, k): # 再次覆盖默认值setattr(m, k, v)else:raise KeyError # 传入非法的k-v# 写入默认数据m.id = next_id(name)# print('debug new id ', m.id)ts = int(time.time())m.created_time = tsm.updated_time = ts# m.deleted = Falsem.type = name.lower()# 特殊 model 的自定义设置# m._setup(form)m.save()return m@classmethoddef _new_with_bson(cls, bson):"""这是给内部 all 这种函数使用的函数从 mongo 数据中恢复一个 model"""m = cls()fields = cls.__fields__.copy()# 去掉 _id 这个特殊的字段fields.remove('_id')for f in fields:k, t, v = f# log("k:{}, t:{}, v:{}".format(k,t,v))if k in bson:setattr(m, k, bson[k])else:# 设置默认值setattr(m, k, v)setattr(m, '_id', bson['_id'])# 这一句必不可少，否则 bson 生成一个新的_id# FIXME, 因为现在的数据库里面未必有 type# 所以在这里强行加上# 以后洗掉db的数据后应该删掉这一句m.type = cls.__name__.lower()return m@classmethoddef all(cls):# 按照 id 升序排序# name = cls.__name__# ds = mongua.db[name].find()# l = [cls._new_with_bson(d) for d in ds]# return lreturn cls._find()# TODO, 还应该有一个函数 find(name, **kwargs)@classmethoddef _find(cls, **kwargs):"""mongo 数据查询"""name = cls.__name__# TODO 过滤掉被删除的元素# kwargs['deleted'] = Falseflag_sort = '__sort'sort = kwargs.pop(flag_sort, None)ds = mongua.db[name].find(kwargs)if sort is not None:ds = ds.sort(sort)# log("ds, ", type(ds))# log("ds_list, ", [d for d in ds])l = [cls._new_with_bson(d) for d in ds]# log("l, ", l)return l@classmethoddef _find_raw(cls, **kwargs):name = cls.__name__ds = mongua.db[name]._find(kwargs)l = [d for d in ds]return l# 直接 list() 就好了# return list(l)@classmethoddef _clean_field(cls, source, target):"""清洗数据用的函数例如 User._clean_field('is_hidden', 'deleted')把 is_hidden 字段全部复制为 deleted 字段"""ms = cls._find()for m in ms:v = getattr(m, source)setattr(m, target, v)m.save()@classmethoddef find_by(cls, **kwargs):return cls.find_one(**kwargs)@classmethoddef find_all(cls, **kwargs):return cls._find(**kwargs)@classmethoddef find(cls, id):return cls.find_one(id=id)@classmethoddef get(cls, id):return cls.find_one(id=id)@classmethoddef find_one(cls, **kwargs):""""""# TODO 过滤掉被删除的元素kwargs['deleted'] = Falsel = cls._find(**kwargs)# print('find one debug', kwargs, l)if len(l) > 0:return l[0]else:return None@classmethoddef upsert(cls, query_form, update_form, hard=False):ms = cls.find_one(**query_form)if ms is None:query_form.update(**update_form)ms = cls.new(query_form)else:ms.update(update_form, hard=hard)return msdef update(self, form, hard=False):for k, v in form.items():if hard or hasattr(self, k):setattr(self, k, v)# self.updated_time = int(time.time()) fixmeself.save()def save(self):name = self.__class__.__name__mongua.db[name].save(self.__dict__)def delete(self):name = self.__class__.__name__query = {'id': self.id,}values = {'deleted': True}mongua.db[name].update_one(query, values)# self.deleted = True# self.save()def blacklist(self):b = ['_id',]return bdef json(self):_dict = self.__dict__d = {k: v for k, v in _dict.items() if k not in self.blacklist()}# TODO, 增加一个 type 属性return ddef data_count(self, cls):"""神奇的函数, 查看用户发表的评论数u.data_count(Comment):return: int"""name = cls.__name__# TODO, 这里应该用 type 替代fk = '{}_id'.format(self.__class__.__name__.lower())query = {fk: self.id,}count = mongua.db[name]._find(query).count()return count