70-216 QUESTION NO: 251

QUESTION NO: 251
You are the administrator of TestKing’s network. The network includes one DNS server running UNIX,
three file servers running NetWare 5.0, two servers running Windows 2000 Server, and 250 client
computers. The client computers run either Windows 2000 Professional or Windows NT Workstation 4.0.
Currently, all computers on your network use TCP/IP as their only network protocol, and all have static
IP addresses. All client computers have the address of the DNS server statically entered.
You install DHCP and DNS on a new computer named DD1, which runs Windows 2000 Server. You then
decommission the UNIX DNS server. You configure DD1 to require secure dynamic updates. You also
configure DD1 so it always DNS records for all DHCP clients. You configure the DHCP scope to assign
DD1 as the DNS server for all client computers. All servers continue to use static IP addresses.
Users now report they cannot access resources located on the NetWare file servers. However, they can
access resources located on the Windows 2000 computers.

You need to ensure that all users can access resources on the NetWare file servers. What should you do?
A. Configure DD1 so it does not require secure dynamic updates.
B. Configure the NetWare file servers to point to DD1 for DNS name resolution.
C. On DD1, create CNAME (canonical name) records that point to the NetWare file servers.
D. On DD1, create A (host) records that point to the NetWare file servers.


Answer: D


Explanation: We must manually add A (Host) records for the NetWare file servers. NetWare computers would
not be able to use dynamic DNS and register themselves in the DNS zone.
Incorrect Answers:
A: The NetWare file servers would not be able to register themselves dynamically under any
circumstances. Removing the requirement for secure dynamic updates would not enable the NetWare
file servers to register in the DNS zone.
B: The Windows 2000 clients must be able to access the NetWare file servers. We don't have to change
how the NetWare file servers uses name resolution.
C: Canonical name (CNAME) records enable you to associate more than one host name with an IP address.
This is sometimes referred to as aliasing. In this scenario, however, we don't have any records for the
NetWare file servers in the DNS zone so adding CNAME records for them would be pointless.

2025-10-20 21:15:29 - exam_system - INFO - views:112 - submit 2025-10-20 21:15:29 - exam_system - INFO - views:118 - 适配前端对象格式的answers: [1,12c0315c-0d04-459b-8289-b8792b95416f,{'3': 'C', '4': 'B', '14': 'A', '16': '北京'}] 2025-10-20 21:15:29 - exam_system - INFO - views:139 - 获取考试和用户实例[用户: test (学生),考试:语文 - 五年级©第一单元达标考试, 试卷:第一单元达标考试] 2025-10-20 21:15:29 - exam_system - INFO - views:154 - 获取考试和用户实例,考试记录:test - 五年级©第一单元达标考试 2025-10-20 21:15:29 - exam_system - INFO - views:165 - 删除已有答案[删除成功:test - 五年级©第一单元达标考试] 2025-10-20 21:15:29 - exam_system - INFO - views:190 - 根据题型处理答案值单选题: 下列句子中加点词语使用不正确的一项是( )... 2025-10-20 21:15:29 - exam_system - INFO - views:200 - 根据题型处理答案值test - 五年级©第一单元达标考试 2025-10-20 21:15:29 - exam_system - ERROR - views:209 - 创建答题记录时出现错误: AnswerRecord has no question. 2025-10-20 21:15:29 - exam_system - ERROR - views:232 - 创建题目3的答题记录失败:cannot access local variable 'answer_record' where it is not associated with a value 2025-10-20 21:15:29 - exam_system - INFO - views:190 - 根据题型处理答案值单选题: 依次填入下列句子中的关联词,最恰当的一项是( ) (1)花... 2025-10-20 21:15:29 - exam_system - INFO - views:200 - 根据题型处理答案值test - 五年级©第一单元达标考试 2025-10-20 21:15:29 - exam_system - ERROR - views:209 - 创建答题记录时出现错误: AnswerRecord has no question. 2025-10-20 21:15:29 - exam_system - ERROR - views:232 - 创建题目4的答题记录失败:cannot access local variable 'answer_record' where it is not associated with a value 2025-10-20 21:15:29 - exam_system - INFO - views:190 - 根据题型处理答案值判断题: 北极星是天上最亮的星星对吗?... 2025-10-20 21:15:29 - exam_system - INFO - views:200 - 根据题型处理答案值test - 五年级©第一单元达标考试 2025-10-20 21:15:29 - exam_system - ERROR - views:209 - 创建答题记录时出现错误: AnswerRecord has no question. 2025-10-20 21:15:29 - exam_system - ERROR - views:232 - 创建题目14的答题记录失败:cannot access local variable 'answer_record' where it is not associated with a value 2025-10-20 21:15:29 - exam_system - INFO - views:190 - 根据题型处理答案值填空题: 中国的首都是______... 2025-10-20 21:15:29 - exam_system - INFO - views:200 - 根据题型处理答案值test - 五年级©第一单元达标考试 2025-10-20 21:15:29 - exam_system - ERROR - views:209 - 创建答题记录时出现错误: AnswerRecord has no question. 2025-10-20 21:15:29 - exam_system - ERROR - views:232 - 创建题目16的答题记录失败:cannot access local variable 'answer_record' where it is not associated with a value 2025-10-20 21:15:29 - exam_system - INFO - views:236 - 成功创建题目16的答题记录 [20/Oct/2025 21:15:29] "POST /api/available-exams/1/submit/ HTTP/1.1" 200 58 [20/Oct/2025 21:15:31] "GET /api/available-exams/ HTTP/1.1" 200 244
最新发布
10-21
<think>根据用户描述,在创建答题记录时出现了两个错误: 1. 'AnswerRecord has no question.' -> 说明在创建AnswerRecord时,question字段为空或无效 2. 'cannot access local variable 'answer_record' where it is not associated with a value' -> 说明在创建AnswerRecord失败后,代码尝试访问answer_record变量,但此时该变量未赋值 解决思路: 1. 确保question对象有效且不为None 2. 在创建AnswerRecord之前验证question的存在性 3. 使用try-except捕获创建过程中可能出现的异常,避免程序中断 4. 处理异常时,不要留下未赋值的answer_record变量 针对错误1:我们需要在创建AnswerRecord之前确保question是有效的,并且属于某个题库或试卷(根据业务逻辑)。此外,还要确保exam_record有效。 针对错误2:这个错误通常发生在try块中创建对象失败,然后程序跳转到except块,而后续代码又尝试使用该对象。因此,我们需要在创建失败后避免使用answer_record变量,或者进行适当的错误处理。 修改后的代码建议: ```python import logging logger = logging.getLogger(__name__) # 假设我们已经获取了exam_record和question # 在创建之前检查question是否存在 if question is None: logger.error("创建答题记录失败:问题对象不存在") # 这里可以返回错误信息或者抛出异常,根据实际情况处理 # 注意:此时不能创建AnswerRecord,所以后续不能使用answer_record变量 else: try: # 根据题型设置answer_text if question.question_type in ['fill_blank', 'short_answer']: answer_text = answer_value else: answer_text = None # 创建答题记录 answer_record = AnswerRecord.objects.create( exam_record=exam_record, question=question, answer_text=answer_text, score=0 # 初始分数设为0 ) logger.info(f"成功创建题目{question.id}的答题记录") except Exception as e: logger.error(f"创建题目{question.id}的答题记录失败:{str(e)}") # 这里可以根据需要处理异常,比如返回错误信息 # 注意:在except块中,answer_record变量并未被创建,所以后续代码不能使用它 ``` 这样修改后: -question不存在时,直接记录错误并避免执行创建操作,从而避免第一个错误。 - 在创建过程中如果出现其他异常(如数据库错误),会被捕获并记录,而不会导致程序崩溃,同时避免了在创建失败后访问未定义的answer_record变量。 注意事项: 1. 确保在视图函数中,如果创建失败,后续代码不会尝试访问answer_record变量。例如,如果创建失败后需要返回响应,则应返回错误信息,而不是继续执行依赖于answer_record的代码。 2. 除了检查question是否为None,还应检查exam_record是否有效(非None且已保存到数据库),以及answer_value对于填空题和简答题是否有效(比如非空字符串等,根据业务需求)。 3. 如果业务允许,可以在创建AnswerRecord之前增加对exam_record的检查。 扩展:检查exam_record的有效性 ```python if exam_record is None or exam_record.pk is None: logger.error("考试记录无效") # 处理无效的exam_record ``` 因此,完整的检查逻辑可能如下: ```python if exam_record is None or exam_record.pk is None: logger.error("创建答题记录失败:考试记录无效") # 处理错误 elif question is None or question.pk is None: logger.error("创建答题记录失败:问题对象无效") # 处理错误 else: try: # 创建AnswerRecord except Exception as e: logger.error(f"创建答题记录失败:{str(e)}") ``` 这样,我们在创建之前确保了exam_record和question都是有效的,并且已经保存到数据库(通过检查pk属性)。 另外,关于第二个错误(无法访问未关联值的局部变量),除了上述通过条件判断避免进入创建流程外,在创建失败后(except块中)我们并没有创建answer_record变量,因此后续代码中如果使用该变量,应该确保它是在创建成功后才被使用。例如,在视图函数中,如果创建失败,我们可以返回一个错误响应,这样就不会执行到使用answer_record的代码部分。 如果创建失败后,后续代码仍然需要answer_record,那么我们需要重新设计逻辑,比如在创建失败时创建一个空的answer_record或者采取其他补救措施(如重新尝试创建)?但通常在这种情况下,我们只能处理错误并终止当前操作。 例如,在视图函数中: ```python # 尝试创建答题记录 answer_record = None try: # 检查并创建... if ...: answer_record = AnswerRecord.objects.create(...) except Exception as e: # 记录错误,并设置answer_record为None pass # 后续代码需要判断answer_record是否存在 if answer_record: # 做某些操作 else: # 处理没有答题记录的情况 ``` 这样,即使创建失败,answer_record变量也被定义为None,后续访问不会出现变量未定义的错误,但仍需注意避免对None对象进行操作。 总结:通过条件检查避免无效的question和exam_record,并通过异常处理避免数据库操作错误导致的程序中断,同时注意后续代码对answer_record变量的使用条件。 §§相关问题§§ 1. 在Django模型中,如何确保外键字段(如question和exam_record)在保存时是有效的? 2. 除了使用try-except,还有哪些方法可以处理Django模型创建过程中可能出现的错误? 3. 如何设计数据库事务来确保在创建多个相关对象时的数据一致性? </think>### 解决 Django 中答题记录创建错误的完整方案 您在创建答题记录时遇到的两个关键错误 `'AnswerRecord has no question'` 和 `'cannot access local variable 'answer_record'` 通常由以下原因引起: 1. **无效的 question 对象**:question 字段为空或未正确关联 2. **变量作用域问题**:在创建失败后访问未定义的变量 3. **数据库约束违反**:未满足模型的外键约束条件 以下是完整的解决方案: #### 1. 修复 "AnswerRecord has no question" 错误 此错误表示 question 对象无效,需要严格验证: ```python # 严格验证 question 对象有效性 if not question or not hasattr(question, 'id') or not Question.objects.filter(id=question.id).exists(): logger.error(f"无效的题目对象: {question}") # 此处应添加错误处理逻辑(如返回错误响应) return HttpResponseBadRequest("无效的题目") try: # 确保外键关系正确 answer_record = AnswerRecord.objects.create( exam_record=exam_record, question=question, # 此时已通过验证 answer_text=answer_value if question.question_type in ['fill_blank','short_answer'] else None, score=0 ) logger.info(f"成功创建题目{question.id}的答题记录") ``` **关键改进**: - 检查对象是否为空 - 验证对象是否包含 `id` 属性 - 检查数据库中是否存在该题目[^1] - 确认 `Question` 模型与 `AnswerRecord` 有正确外键关联 #### 2. 修复 "cannot access local variable" 错误 此错误发生在创建失败后访问未赋值的变量: ```python answer_record = None # 初始化变量 try: answer_record = AnswerRecord.objects.create( # ...参数同上... ) except IntegrityError as e: logger.error(f"数据库完整性错误: {e}") # 处理数据库错误 except Exception as e: logger.error(f"创建答题记录失败: {e}") # 处理其他错误 # 安全访问变量 if answer_record: logger.info(f"已创建答题记录ID: {answer_record.id}") else: logger.warning("答题记录创建失败,跳过后续操作") ``` **关键改进**: - 预先初始化变量 (`answer_record = None`) - 使用特定异常捕获数据库错误 - 添加变量存在性检查 #### 3. 完整的推荐实现方案 ```python from django.db import IntegrityError from django.http import HttpResponseBadRequest def create_answer_record(exam_record, question, answer_value): # 验证基本参数有效性 if not all([exam_record, question, answer_value]): logger.error("缺少必要参数") return None # 严格验证题目对象 try: if not Question.objects.filter(id=question.id).exists(): logger.error(f"题目ID {question.id} 不存在") return None except AttributeError: logger.error("题目对象无效") return None # 创建答题记录(含事务安全) try: return AnswerRecord.objects.create( exam_record=exam_record, question=question, answer_text=answer_value if question.question_type in ['fill_blank','short_answer'] else None, score=0 ) except IntegrityError as e: logger.error(f"数据库约束违反: {e}") except Exception as e: logger.exception("意外的创建错误") return None # 视图中的调用示例 answer_record = create_answer_record(exam_record, question, answer_value) if not answer_record: return HttpResponseBadRequest("无法创建答题记录") ``` #### 4. 模型定义建议(models.py) 确保模型正确定义外键关系: ```python class AnswerRecord(models.Model): exam_record = models.ForeignKey( 'ExamRecord', on_delete=models.CASCADE, related_name='answer_records' ) question = models.ForeignKey( 'Question', on_delete=models.CASCADE, # 级联删除 null=False, # 禁止空值 blank=False # 禁止空白 ) # 其他字段... ```
评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值