分页
如果你的数据库中有数百万的记录，你肯定不希望将其一骨碌地给到同一个页面中。那样的话，客户端和服务端都无法承受。所以，你需要分页。
添加分页逻辑
调整方法参数，domain/gateway/book_manager.py:
@@ -22,5 +22,5 @@ class BookManager(ABC):
pass
@abstractmethod
- def get_books(self) -> List[Book]:
+ def get_books(self, offset: int) -> List[Book]:
pass
为 get_books 方法添加名为 offset 的参数。
添加 page_size 配置项，infrastructure/config/config.py:
@@ -25,6 +25,7 @@ class CacheConfig:
@dataclass
class ApplicationConfig:
port: int
+ page_size: int
@dataclass
设置 page_size 配置值，config.yml:
@@ -1,5 +1,6 @@
app:
port: 5000
+ page_size: 5
db:
file_name: "test.db"
host: "127.0.0.1"
合入 page_size，application/wire_helper.py:
@@ -12,7 +12,7 @@ class WireHelper:
@classmethod
def new(cls, c: Config):
- db = MySQLPersistence(c.db)
+ db = MySQLPersistence(c.db, c.app.page_size)
mdb = MongoPersistence(c.db.mongo_uri, c.db.mongo_db_name)
kv = RedisCache(c.cache)
return cls(db, mdb, kv)
更新查询逻辑，将 offset 和 page_size 考虑进去，infrastructure/database/mysql.py:
@@ -8,7 +8,8 @@ from ...domain.model import Book
class MySQLPersistence(BookManager):
- def __init__(self, c: DBConfig):
+ def __init__(self, c: DBConfig, page_size: int):
+ self.page_size = page_size
self.conn = mysql.connector.connect(
host=c.host,
port=c.port,
@@ -60,9 +61,9 @@ class MySQLPersistence(BookManager):
return None
return Book(**result)
- def get_books(self) -> List[Book]:
+ def get_books(self, offset: int) -> List[Book]:
self.cursor.execute('''
- SELECT * FROM books
- ''')
+ SELECT * FROM books LIMIT %s, %s
+ ''', (offset, self.page_size))
results: List[Any] = self.cursor.fetchall()
return [Book(**result) for result in results]
调整缓存键，application/executor/book_operator.py:
@@ -23,13 +23,14 @@ class BookOperator():
def get_book(self, id: int) -> Optional[Book]:
return self.book_manager.get_book(id)
- def get_books(self) -> List[Book]:
- v = self.cache_helper.load(BOOKS_KEY)
+ def get_books(self, offset: int) -> List[Book]:
+ k = f"{BOOKS_KEY}-{offset}"
+ v = self.cache_helper.load(k)
if v:
return json.loads(v)
- books = self.book_manager.get_books()
+ books = self.book_manager.get_books(offset)
self.cache_helper.save(
- BOOKS_KEY, json.dumps([_convert(b) for b in books]))
+ k, json.dumps([_convert(b) for b in books]))
return books
def update_book(self, id: int, b: Book) -> Book:
最后一步，在 adapter/router.py 中传递 query 参数：
@@ -15,7 +15,8 @@ class RestHandler:
def get_books(self):
try:
- books = self.book_operator.get_books()
+ offset = request.args.get("o", type=int) or 0
+ books = self.book_operator.get_books(offset)
return jsonify(books), 200
except Exception as e:
self._logger.error(f"Failed to get books: {e}")
好啦！改完啦！让我们试下。
使用 curl 测试
放入待测试数据：
curl -X POST -H "Content-Type: application/json" -d '{"title": "The Great Gatsby", "author": "F. Scott Fitzgerald", "published_at": "1925-04-10", "description": "A novel depicting the opulent lives of wealthy Long Island residents during the Jazz Age.", "isbn": "9780743273565", "total_pages": 218}' http://localhost:5000/books
curl -X POST -H "Content-Type: application/json" -d '{"title": "To Kill a Mockingbird", "author": "Harper Lee", "published_at": "1960-07-11", "description": "A novel set in the American South during the 1930s, dealing with themes of racial injustice and moral growth.", "isbn": "9780061120084", "total_pages": 281}' http://localhost:5000/books
curl -X POST -H "Content-Type: application/json" -d '{"title": "1984", "author": "George Orwell", "published_at": "1949-06-08", "description": "A dystopian novel depicting a totalitarian regime, surveillance, and propaganda.", "isbn": "9780451524935", "total_pages": 328}' http://localhost:5000/books
curl -X POST -H "Content-Type: application/json" -d '{"title": "Pride and Prejudice", "author": "Jane Austen", "published_at": "1813-01-28", "description": "A classic novel exploring the themes of love, reputation, and social class in Georgian England.", "isbn": "9780486284736", "total_pages": 279}' http://localhost:5000/books
curl -X POST -H "Content-Type: application/json" -d '{"title": "The Catcher in the Rye", "author": "J.D. Salinger", "published_at": "1951-07-16", "description": "A novel narrated by a disaffected teenager, exploring themes of alienation and identity.", "isbn": "9780316769488", "total_pages": 277}' http://localhost:5000/books
curl -X POST -H "Content-Type: application/json" -d '{"title": "The Lord of the Rings", "author": "J.R.R. Tolkien", "published_at": "1954-07-29", "description": "A high fantasy epic following the quest to destroy the One Ring and defeat the Dark Lord Sauron.", "isbn": "9780544003415", "total_pages": 1178}' http://localhost:5000/books
curl -X POST -H "Content-Type: application/json" -d '{"title": "Moby-Dick", "author": "Herman Melville", "published_at": "1851-10-18", "description": "A novel exploring themes of obsession, revenge, and the nature of good and evil.", "isbn": "9780142000083", "total_pages": 624}' http://localhost:5000/books
curl -X POST -H "Content-Type: application/json" -d '{"title": "The Hobbit", "author": "J.R.R. Tolkien", "published_at": "1937-09-21", "description": "A fantasy novel set in Middle-earth, following the adventure of Bilbo Baggins and the quest for treasure.", "isbn": "9780345339683", "total_pages": 310}' http://localhost:5000/books
curl -X POST -H "Content-Type: application/json" -d '{"title": "The Adventures of Huckleberry Finn", "author": "Mark Twain", "published_at": "1884-12-10", "description": "A novel depicting the journey of a young boy and an escaped slave along the Mississippi River.", "isbn": "9780486280615", "total_pages": 366}' http://localhost:5000/books
curl -X POST -H "Content-Type: application/json" -d '{"title": "War and Peace", "author": "Leo Tolstoy", "published_at": "1869-01-01", "description": "A novel depicting the Napoleonic era in Russia, exploring themes of love, war, and historical determinism.", "isbn": "9781400079988", "total_pages": 1392}' http://localhost:5000/books
curl -X POST -H "Content-Type: application/json" -d '{"title": "Alice’s Adventures in Wonderland", "author": "Lewis Carroll", "published_at": "1865-11-26", "description": "A children’s novel featuring a young girl named Alice who falls into a fantastical world populated by peculiar creatures.", "isbn": "9780141439761", "total_pages": 192}' http://localhost:5000/books
curl -X POST -H "Content-Type: application/json" -d '{"title": "The Odyssey", "author": "Homer", "published_at": "8th Century BC", "description": "An ancient Greek epic poem attributed to Homer, detailing the journey of Odysseus after the Trojan War.", "isbn": "9780140268867", "total_pages": 541}' http://localhost:5000/books
列出第一页的图书：
curl -X GET http://localhost:5000/books
结果：
[
{
"author": "John Doe",
"created_at": "Fri, 01 Mar 2024 12:11:57 GMT",
"description": "A sample book description",
"id": 2,
"isbn": "1234567890",
"published_at": "2023-01-01",
"title": "Sample Book 222",
"total_pages": 200,
"updated_at": "Fri, 01 Mar 2024 12:11:57 GMT"
},
{
"author": "John Doe",
"created_at": "Fri, 01 Mar 2024 12:40:16 GMT",
"description": "A sample book description",
"id": 3,
"isbn": "1234567890",
"published_at": "2023-01-01",
"title": "Sample Book",
"total_pages": 200,
"updated_at": "Fri, 01 Mar 2024 12:40:16 GMT"
},
{
"author": "F. Scott Fitzgerald",
"created_at": "Sat, 02 Mar 2024 05:48:25 GMT",
"description": "A novel depicting the opulent lives of wealthy Long Island residents during the Jazz Age.",
"id": 4,
"isbn": "9780743273565",
"published_at": "1925-04-10",
"title": "The Great Gatsby",
"total_pages": 218,
"updated_at": "Sat, 02 Mar 2024 05:48:25 GMT"
},
{
"author": "Harper Lee",
"created_at": "Sat, 02 Mar 2024 05:48:25 GMT",
"description": "A novel set in the American South during the 1930s, dealing with themes of racial injustice and moral growth.",
"id": 5,
"isbn": "9780061120084",
"published_at": "1960-07-11",
"title": "To Kill a Mockingbird",
"total_pages": 281,
"updated_at": "Sat, 02 Mar 2024 05:48:25 GMT"
},
{
"author": "George Orwell",
"created_at": "Sat, 02 Mar 2024 05:48:25 GMT",
"description": "A dystopian novel depicting a totalitarian regime, surveillance, and propaganda.",
"id": 6,
"isbn": "9780451524935",
"published_at": "1949-06-08",
"title": "1984",
"total_pages": 328,
"updated_at": "Sat, 02 Mar 2024 05:48:25 GMT"
}
]
列出偏移之后的图书：
curl -X GET "http://localhost:5000/books?o=5"
结果：
[
{
"author": "Jane Austen",
"created_at": "Sat, 02 Mar 2024 05:48:25 GMT",
"description": "A classic novel exploring the themes of love, reputation, and social class in Georgian England.",
"id": 7,
"isbn": "9780486284736",
"published_at": "1813-01-28",
"title": "Pride and Prejudice",
"total_pages": 279,
"updated_at": "Sat, 02 Mar 2024 05:48:25 GMT"
},
{
"author": "J.D. Salinger",
"created_at": "Sat, 02 Mar 2024 05:48:25 GMT",
"description": "A novel narrated by a disaffected teenager, exploring themes of alienation and identity.",
"id": 8,
"isbn": "9780316769488",
"published_at": "1951-07-16",
"title": "The Catcher in the Rye",
"total_pages": 277,
"updated_at": "Sat, 02 Mar 2024 05:48:25 GMT"
},
{
"author": "J.R.R. Tolkien",
"created_at": "Sat, 02 Mar 2024 05:48:25 GMT",
"description": "A high fantasy epic following the quest to destroy the One Ring and defeat the Dark Lord Sauron.",
"id": 9,
"isbn": "9780544003415",
"published_at": "1954-07-29",
"title": "The Lord of the Rings",
"total_pages": 1178,
"updated_at": "Sat, 02 Mar 2024 05:48:25 GMT"
},
{
"author": "Herman Melville",
"created_at": "Sat, 02 Mar 2024 05:48:25 GMT",
"description": "A novel exploring themes of obsession, revenge, and the nature of good and evil.",
"id": 10,
"isbn": "9780142000083",
"published_at": "1851-10-18",
"title": "Moby-Dick",
"total_pages": 624,
"updated_at": "Sat, 02 Mar 2024 05:48:25 GMT"
},
{
"author": "J.R.R. Tolkien",
"created_at": "Sat, 02 Mar 2024 05:48:25 GMT",
"description": "A fantasy novel set in Middle-earth, following the adventure of Bilbo Baggins and the quest for treasure.",
"id": 11,
"isbn": "9780345339683",
"published_at": "1937-09-21",
"title": "The Hobbit",
"total_pages": 310,
"updated_at": "Sat, 02 Mar 2024 05:48:25 GMT"
}
]
列出另一个偏移后的图书：
curl -X GET "http://localhost:5000/books?o=10"
结果：
[
{
"author": "Mark Twain",
"created_at": "Sat, 02 Mar 2024 05:48:25 GMT",
"description": "A novel depicting the journey of a young boy and an escaped slave along the Mississippi River.",
"id": 12,
"isbn": "9780486280615",
"published_at": "1884-12-10",
"title": "The Adventures of Huckleberry Finn",
"total_pages": 366,
"updated_at": "Sat, 02 Mar 2024 05:48:25 GMT"
},
{
"author": "Leo Tolstoy",
"created_at": "Sat, 02 Mar 2024 05:48:25 GMT",
"description": "A novel depicting the Napoleonic era in Russia, exploring themes of love, war, and historical determinism.",
"id": 13,
"isbn": "9781400079988",
"published_at": "1869-01-01",
"title": "War and Peace",
"total_pages": 1392,
"updated_at": "Sat, 02 Mar 2024 05:48:25 GMT"
},
{
"author": "Lewis Carroll",
"created_at": "Sat, 02 Mar 2024 05:48:25 GMT",
"description": "A children\u2019s novel featuring a young girl named Alice who falls into a fantastical world populated by peculiar creatures.",
"id": 14,
"isbn": "9780141439761",
"published_at": "1865-11-26",
"title": "Alice\u2019s Adventures in Wonderland",
"total_pages": 192,
"updated_at": "Sat, 02 Mar 2024 05:48:25 GMT"
},
{
"author": "Homer",
"created_at": "Sat, 02 Mar 2024 05:48:25 GMT",
"description": "An ancient Greek epic poem attributed to Homer, detailing the journey of Odysseus after the Trojan War.",
"id": 15,
"isbn": "9780140268867",
"published_at": "8th Century BC",
"title": "The Odyssey",
"total_pages": 541,
"updated_at": "Sat, 02 Mar 2024 05:48:25 GMT"
},
{
"author": "John Doe",
"created_at": "Thu, 07 Mar 2024 10:17:59 GMT",
"description": "A sample book description",
"id": 16,
"isbn": "1234567890",
"published_at": "2023-01-01",
"title": "Sample Book",
"total_pages": 200,
"updated_at": "Thu, 07 Mar 2024 10:17:59 GMT"
}
]
看来分页功能一切正常！进展不错！
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> 此处输出代码运行结果