你的代码整体结构清晰，功能完整，但存在多个 **关键错误和潜在 bug**，导致程序在运行时会崩溃或行为异常。我们来逐个分析并修复问题。
---
## 🔴 问题 1：`KeyError
: 'P0101'` 的根本原因
你遇到的 `KeyError
: 'P0101'` 是因为你在 `borrow_return_console` 中尝试访问 `
books[borrowid]`，而该 ID 不在 `
books` 字典中。
但是从你的代码来看，这个问题很可能是因为：
### ❌ 错误地使用了 `valid_ids` 列表
```python
valid_ids = [b.book_id
for b
in all_matches]
```
这里 `all_matches` 包含的是搜索结果中的书（已过滤），但后续你直接用用户输入的 `borrowid` 去查全局 `
books` 字典：
```python
book =
books[borrowid] # ⚠️ 这里可能 KeyError！
```
虽然你检查了 `borrowid not
in valid_ids`，但由于 `valid_ids` 来自局部变量 `all_matches`，如果用户输入了一个不在搜索结果里的合法书籍 ID（比如拼错、或者跳过搜索直接输错 ID），就会出错。
更严重的是：即使 `borrowid` 在 `valid_ids` 中，也不能保证它一定在 `
books` 字典中 —— 实际上应该是一致的，但如果加载失败就不是。
✅ **解决方案：始终确保 `
books` 加载正确，并对所有访问做安全检查**
---
## ✅ 修复建议与完整修正版代码（重点部分）
### ✅ 修复点 1：防止 `KeyError` 安全访问书籍
修改 `borrow` 分支中获取书籍的部分：
```python
# 原始代码有风险
book =
books[borrowid]
# 改为：
if borrowid not
in books:
pr
int(f"❌ Book ID '{borrowid}' does not exist.")
cont
inue
book =
books[borrowid]
```
同时，在 `return` 和 `renew` 操作中也应如此处理。
---
### ✅ 修复点 2：`
search_by_keywords` 函数语法错误严重
当前函数中有多个致命错误：
```python
def
search_by_keywords(
books)
:
...
for b
in book.values()
: # ❌ book 未定义，应为
books
matched = sum(...) # ❌ keywords
in keywords? 逻辑错误
result.append(book, matched) # ❌ append 接受一个参数
```
#### ✅ 正确实现如下：
```python
def
search_by_keywords(
books)
:
keyword_
input =
input("Enter
search keywords (separated by comma)
: ").strip().lower()
if not keyword_
input
:
pr
int("Found 0 book(s).")
return
keywords = [k.strip()
for k
in keyword_
input.split(',') if k.strip()]
result = []
for b
in books.values()
:
title_match = any(k
in b.title.lower()
for k
in keywords)
keyword_match = any(k
in kw.lower()
for k
in keywords
for kw
in b.keywords)
if title_match or keyword_match
:
match_count = sum(
1
for k
in keywords
if k
in b.title.lower() or any(k
in kw.lower()
for kw
in b.keywords)
)
result.append((b, match_count))
# Sort by
: match count ↓, year ↓, book_id ↑
result.sort(key=lambda x
: (-x[1], -x[0].year, x[0].book_id))
pr
int(f"Found {len(result)} book(s).")
for i, (book, matches)
in enumerate(result, 1)
:
copies_
info = f"Available copies
: {book.available_copies()}/{book.total_copies}" \
if book.book_type == "physical" else "Available copies
: N/A"
pr
int(f"{i}. {book.book_id} '{book.title}' by {book.authors} ({book.year}). {copies_
info}")
```
> ⚠️ 注意：假设 `Book` 类中 `keywords` 是列表类型，如 `["AI", "Mach
ine Learn
ing"]`
---
### ✅ 修复点 3：`manage_library` 函数中的严重语法错误
#### ❌ 原始错误代码：
```python
for b
in books.value()
: # ❌ 应为 .values()
all_keywords.update(
books.keywords) # ❌
books 是 dict，没有 .keywords
...
new_book = book(new_id, ...) # ❌ 小写 book 是模块名，不能当构造器
book[new_id] = new_book # ❌ 同样，book 是模块
```
#### ✅ 修复后版本：
```python
def manage_library(users,
books)
:
while True
:
cmd =
input("> ").strip()
if cmd == "quit"
:
break
elif cmd == "report"
:
total_user = len(users)
students = sum(1
for u
in users.values() if u.user_id.startswith('s'))
staffs = sum(1
for u
in users.values() if u.user_id.startswith('e'))
o
thers = sum(1
for u
in users.values() if u.user_id.lower().startswith('o'))
total_
books = len(
books)
physical_
books = sum(1
for b
in books.values() if b.book_type == "physical")
available_physical = sum(b.available_copies()
for b
in books.values() if b.book_type == "physical")
onl
ine_
books = sum(1
for b
in books.values() if b.book_type == "onl
ine")
pr
int("Library report")
pr
int(f"- {total_user} users,
includ
ing {students} student(s), {staffs} staff, and {o
thers} o
thers.")
pr
int(f"- {total_
books}
books,
includ
ing {physical_
books} physical book(s) "
f"({available_physical} currently available) and {onl
ine_
books} onl
ine book(s).")
elif cmd.startswith("add ")
:
parts = cmd.split(" ", 2)
if len(parts) < 2
:
pr
int("
Invalid command
format. Use
: add <physical|onl
ine>")
cont
inue
book_type = parts[1]
if book_type not
in ["physical", "onl
ine"]
:
pr
int("
Invalid book type. Use 'physical' or 'onl
ine'.")
cont
inue
title =
input("Title
: ").strip()
authors =
input("Authors
: ").strip()
try
:
year =
int(
input("Year
: ").strip())
except ValueError
:
pr
int("
Invalid year.")
cont
inue
if book_type == "physical"
:
try
:
copies =
int(
input("Copies
: ").strip())
except ValueError
:
pr
int("
Invalid number
of copies.")
cont
inue
else
:
copies = 0
# Detect exist
ing keywords from all
books
all_keywords_set = set()
for b
in books.values()
:
all_keywords_set.update(kw.lower()
for kw
in b.keywords)
detected_keywords = list(set(word.lower()
for word
in title.split()) & all_keywords_set)
detected_keywords.sort()
keywords_str = "
:".jo
in(detected_keywords)
pr
int(f"Detected keywords
: {keywords_str}")
# Generate new ID
prefix = 'P' if book_type == "physical" else 'E'
exist
ing_ids = [
int(b.book_id[1
:])
for b
in books.values()
if b.book_id.startswith(prefix) and b.book_id[1
:].isdigit()
]
new_id_num = max(exist
ing_ids) + 1 if exist
ing_ids else 1
new_id = f"{prefix}{new_id_num
:04d}" # e.g., P0101
# Create new book us
ing
the Book class
new_book = book.Book(new_id, book_type, copies, title, authors, year, detected_keywords)
books[new_id] = new_book
pr
int(f"✅ Added {new_id} '{title}' by {authors} ({year}). Keywords
: {keywords_str}")
else
:
pr
int("Unknown command. Type 'report' or 'add physical/onl
ine'")
```
> 📝 注意：调用的是 `book.Book(...)`，不是小写的 `book(...)`
---
### ✅ 修复点 4：`renew` 功能逻辑错误
原代码判断 f
ine 是否 > 0 写法有问题：
```python
for loan
in user.get_active_loans()
:
if
int(loan.calculate_f
ine()) > 0
: # ❌ 即使一本有 f
ine 就拒绝全部？
pr
int("Renewal denied...")
cont
inue # ❌ cont
inue 只跳出循环，不中断外层
```
这会导致打印多次提示信息，且无法阻止续借。
#### ✅ 正确做法：
```python
elif action == "renew"
:
borrowid = query.strip()
if borrowid not
in books:
pr
int(f"No such book with ID '{borrowid}'.")
cont
inue
book =
books[borrowid]
active_loans = [loan
for loan
in user.get_active_loans() if loan.book.book_id == borrowid]
if not active_loans
:
pr
int(f"You have no active loan
for '{borrowid}'.")
cont
inue
loan_to_renew = m
in(active_loans, key=lambda x
: x.due_date)
# Check unpaid f
ines
if loan_to_renew.calculate_f
ine() > 0
:
pr
int("Renewal denied
: You have unpaid f
ines.")
cont
inue
# Check already overdue
if TODAY > loan_to_renew.due_date
:
grace = {"Student"
: 0, "Staff"
: 2, "O
thers"
: 0}[user.role]
effective_due = loan_to_renew.due_date + timedelta(days=grace)
if TODAY > effective_due
:
pr
int("Renewal denied
: This book is already overdue beyond grace period.")
cont
inue
# Check renewal limit
if hasattr(loan_to_renew, 'renewed') and loan_to_renew.renewed
:
pr
int("Renewal unavailable
: Each book can only be renewed once.")
cont
inue
# Per
form renewal
loan_to_renew.due_date += timedelta(days=5)
if not hasattr(loan_to_renew, 'renewed')
:
loan_to_renew.renewed = False # 初始化字段（可选）
loan_to_renew.renewed = True
pr
int(f"✅ Renewed '{book.title}' successfully. New due date
: {loan_to_renew.due_date.strftime('%d/%m/%Y')}")
```
---
### ✅ 其他小问题汇总
| 问题 | 说明 |
|------|------|
| `TODAY = ...` 被多次定义 | 提取为常量更好 |
| `book.is_available()` 方法未定义 | 需要在 `Book` 类中实现 |
| 用户三次登录失败后仍继续主循环 | 应 `cont
inue` 回到欢迎界面 |
---
## ✅ 最佳实践建议
### ✅ 建议添加的 `Book.is_available()` 方法
```python
# 在 book.py 中
def is_available(self)
:
return self.available_copies() > 0
```
### ✅ 统一 `TODAY` 时间常量
```python
TODAY = datetime.datetime.strptime("15/09/2025", "%d/%m/%Y").date()
```
放在文件顶部作为全局常量。
---
## ✅ 总结：你现在最需要改的地方
- ✅ 修复 `
search_by_keywords` 的语法错误
- ✅ 修复 `manage_library` 中的变量命名错误（`book` vs `
books`）
- ✅ 所有 `
books[borrowid]` 前加 `if borrowid
in books`
- ✅ `renew` 功能要单独检查目标 loan 的 f
ine
- ✅ 确保 `Loan` 对象上有 `renewed` 属性初始化
---
博客提及经济学的困惑与悖论，还列举了多本经济学相关书籍，如《The Naked Future》《The Economic Naturalist》系列等，这些书籍围绕用经济学解释日常现象、应对困境等内容。
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