Jupyter测试AnimalShelter类时出现'无create属性'报错求助

问题背景 #

在Jupyter Notebook测试自定义的AnimalShelter.py代码时，持续收到错误：'AnimalShelter'对象没有'create'属性，但已在类中定义create方法，附上完整代码及测试代码请求排查。

原代码展示 #

AnimalShelter.py #

import pymongo
from pymongo import MongoClient
from bson.objectid import ObjectId

class AnimalShelter(object):
    """ CRUD operations for Animal collection in MongoDB """

    def __init__(self, username, password):
        #Initializing the MongoClient. This helps to access the MongoDB databases and collections.
        self.client = MongoClient('mongodb://%s:%s@localhost:45344' % (username, password))
        #where xxxx is your unique port number
        self.database = self.client['AAC']
    
#Complete this create method to implement the C in CRUD.
    def create(self, data):
        if data is not None:
            insert = self.database.animals.insert(data) #data should be dictionary
        
        else:
            raise Exception("Nothing to save, because data parameter is empty")
            
#Create method to implement the R in CRUD.
    def read(self, searchData):
        if searchData:
            data = self.database.animals.find(searchData, {"_id": False})
        
        else:
            data = self.database.animals.find({}, {"_id": False})
        return data

#Create method to implement U in CRUD.
    def update(self, searchData, updateData):
        if searchData is not None:
            result = self.database.animals.update_many(searchData, {"$set": updateData})
        else:
            return "{}"
        return result.raw_result

#Create method to implement D in CRUD.
    def delete(self, deleteData):
        if deleteData is not None:
            result = self.database.animals.delete_many(deleteData)
        
        else:
            return "{}"
        return result.raw_result

测试代码 #

from AnimalShelter import AnimalShelter

data = {}
query = {}

test_class = AnimalShelter()

#test each function in the AnimalShelter class
response = test_class.create(data)
assert response

response = test_class.read(data)
assert response

response = test_class.update(data)
assert response

response = test_class.delete(data)
assert response

错误原因及修复步骤 #

1. 类方法缩进错误（核心问题） #

原代码中create、read、update、delete方法未缩进，导致这些方法不属于AnimalShelter类的成员，而是全局函数。实例化对象后自然找不到create属性。

修复： 将所有方法缩进，使其与__init__方法对齐，成为类的内部方法。

2. __init__方法参数缺失 #

测试代码实例化AnimalShelter时未传入username和password，但类的构造方法明确要求这两个参数，会直接触发报错。

修复： 实例化时传入MongoDB的用户名和密码：

test_class = AnimalShelter('你的用户名', '你的密码')

3. create方法无返回值 #

原create方法执行插入操作后未返回结果，测试代码中的assert response会失败（因为response为None）。

修复： 在create方法中添加返回语句，同时替换过时的insert方法为insert_one：

def create(self, data):
    if data is not None and isinstance(data, dict):
        result = self.database.animals.insert_one(data)
        return result.inserted_id
    else:
        raise Exception("Nothing to save, because data parameter is empty or not a dictionary")

4. update方法参数不足 #

原update方法需要两个参数（searchData和updateData），但测试代码中只传了一个参数，会触发参数数量错误。

修复： 测试时传入更新数据：

response = test_class.update({"name": "测试狗狗"}, {"age": 3})

5. 空字典测试数据风险 #

测试用的data = {}会导致create方法抛出异常，同时delete(data)会删除集合中所有数据，建议使用非空测试数据：

test_data = {"name": "测试狗狗", "type": "狗", "age": 2}

修复后的完整代码 #

AnimalShelter.py #

import pymongo
from pymongo import MongoClient
from bson.objectid import ObjectId

class AnimalShelter(object):
    """ CRUD operations for Animal collection in MongoDB """

    def __init__(self, username, password):
        #Initializing the MongoClient. This helps to access the MongoDB databases and collections.
        self.client = MongoClient('mongodb://%s:%s@localhost:45344' % (username, password))
        #where xxxx is your unique port number
        self.database = self.client['AAC']
    
    #Complete this create method to implement the C in CRUD.
    def create(self, data):
        if data is not None and isinstance(data, dict):
            result = self.database.animals.insert_one(data)
            return result.inserted_id
        else:
            raise Exception("Nothing to save, because data parameter is empty or not a dictionary")
            
    #Create method to implement the R in CRUD.
    def read(self, searchData):
        if searchData and isinstance(searchData, dict):
            data = self.database.animals.find(searchData, {"_id": False})
        else:
            data = self.database.animals.find({}, {"_id": False})
        return list(data)  # 返回列表而非游标，方便断言

    #Create method to implement U in CRUD.
    def update(self, searchData, updateData):
        if searchData is not None and isinstance(searchData, dict) and updateData:
            result = self.database.animals.update_many(searchData, {"$set": updateData})
            return result.raw_result
        else:
            return "{}"

    #Create method to implement D in CRUD.
    def delete(self, deleteData):
        if deleteData is not None and isinstance(deleteData, dict):
            result = self.database.animals.delete_many(deleteData)
            return result.raw_result
        else:
            return "{}"

修复后的测试代码 #

from AnimalShelter import AnimalShelter

# 使用非空测试数据
test_data = {"name": "测试狗狗", "type": "狗", "age": 2}
update_data = {"age": 3}

# 实例化时传入MongoDB的用户名和密码
test_class = AnimalShelter('你的用户名', '你的密码')

# 测试create方法
response = test_class.create(test_data)
assert response is not None

# 测试read方法
response = test_class.read({"name": "测试狗狗"})
assert len(response) > 0

# 测试update方法
response = test_class.update({"name": "测试狗狗"}, update_data)
assert response['nModified'] >= 0

# 测试delete方法
response = test_class.delete({"name": "测试狗狗"})
assert response['nRemoved'] >= 0

内容的提问来源于stack exchange，提问作者GuillyStudiesCode