我创建了一个带有一个表的小型数据库，并在其中填充了数据。它工作得很好。然而，在我退出VSCode并再次输入它之后，代码识别DB并发出请求，但结果得到一个空列表(好像它没有"看到"DB条目)。数据库中充满了数据;我可以在DB浏览器中看到它。此外，从第一个文件导入DBmodel的另一个文件中的代码成功地获得了正确的数据。第一个文件可能有什么问题?第一个文件(app.py):
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///myDB.db'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False # I tried also True
with app.app_context():
db = SQLAlchemy(app)
class Recipy(db.Model):
id = db.Column(db.Integer, primary_key = True)
title = db.Column(db.String(100), index = True, unique = True)
…
db.create_all()
@app.route('/')
def index():
rows=Recipy.query.all()
print(rows) # it is just to have results on terminal; results are an empty list [] both here and on the html-page
return render_template("home.html", rows=rows, search_form=search_form)
…
if __name__ == '__main__':
app.run()
>>> []
第二个成功获取数据的文件:
from app import app, db, Recipy
with app.app_context():
a=Recipy.query.get(2)
rows=Recipy.query.order_by(Recipy.title).all()
print(a, rows)
>>> <Recipy 2> [<Recipy 1>, <Recipy 2>, …]
两个文件在同一个文件夹中。两次我都在同一个venv内运行它。如果你能给点提示，我将非常感激。
我试过app.config[' sqlalchemy_track_modification '] = True我还尝试了在另一个文件夹中创建的类似代码片段，其中包含另一个数据库(其中包括两个表)，但结果是相同的。
更新:根据评论，我添加了app.config["SQLALCHEMY_ECHO"] = "debug"。终端输出如下所示:对于第一个函数:
023-01-10 17:23:27,458 DEBUG sqlalchemy.pool.impl.NullPool Created new connection <sqlite3.Connection object at 0x00000268DFA0DB40>
2023-01-10 17:23:27,459 DEBUG sqlalchemy.pool.impl.NullPool Connection <sqlite3.Connection object at 0x00000268DFA0DB40> checked out from pool
2023-01-10 17:23:27,460 INFO sqlalchemy.engine.Engine BEGIN (implicit)
2023-01-10 17:23:27,467 INFO sqlalchemy.engine.Engine SELECT recipy.id AS recipy_id, recipy.title AS recipy_title, recipy.author AS recipy_author, recipy.ingredients AS recipy_ingredients, recipy.instructions AS recipy_instructions
FROM recipy
2023-01-10 17:23:27,468 INFO sqlalchemy.engine.Engine [generated in 0.00207s] ()
2023-01-10 17:23:27,470 DEBUG sqlalchemy.engine.Engine Col ('recipy_id', 'recipy_title', 'recipy_author', 'recipy_ingredients', 'recipy_instructions')
[]
2023-01-10 17:23:27,491 INFO sqlalchemy.engine.Engine ROLLBACK
2023-01-10 17:23:27,494 DEBUG sqlalchemy.pool.impl.NullPool Connection <sqlite3.Connection object at 0x00000268DFA0DB40> being returned to pool
2023-01-10 17:23:27,501 DEBUG sqlalchemy.pool.impl.NullPool Connection <sqlite3.Connection object at 0x00000268DFA0DB40> rollback-on-return
2023-01-10 17:23:27,504 DEBUG sqlalchemy.pool.impl.NullPool Closing connection <sqlite3.Connection object at 0x00000268DFA0DB40>
对于返回结果的函数:
2023-01-10 18:15:46,205 DEBUG sqlalchemy.pool.impl.NullPool Created new connection <sqlite3.Connection object at 0x00000286178E9B40>
2023-01-10 18:15:46,205 DEBUG sqlalchemy.pool.impl.NullPool Connection <sqlite3.Connection object at 0x00000286178E9B40> checked out from pool
2023-01-10 18:15:46,216 INFO sqlalchemy.engine.Engine BEGIN (implicit)
2023-01-10 18:15:46,217 INFO sqlalchemy.engine.Engine PRAGMA main.table_info("recipy")
2023-01-10 18:15:46,218 INFO sqlalchemy.engine.Engine [raw sql] ()
2023-01-10 18:15:46,219 DEBUG sqlalchemy.engine.Engine Col ('cid', 'name', 'type', 'notnull', 'dflt_value', 'pk')
2023-01-10 18:15:46,220 DEBUG sqlalchemy.engine.Engine Row (0, 'id', 'INTEGER', 1, None, 1)
2023-01-10 18:15:46,220 DEBUG sqlalchemy.engine.Engine Row (1, 'title', 'VARCHAR(100)', 0, None, 0)
2023-01-10 18:15:46,221 DEBUG sqlalchemy.engine.Engine Row (2, 'author', 'VARCHAR(40)', 0, None, 0)
2023-01-10 18:15:46,222 DEBUG sqlalchemy.engine.Engine Row (3, 'ingredients', 'VARCHAR(500)', 0, None, 0)
2023-01-10 18:15:46,223 DEBUG sqlalchemy.engine.Engine Row (4, 'instructions', 'VARCHAR(4000)', 0, None, 0)
2023-01-10 18:15:46,224 INFO sqlalchemy.engine.Engine COMMIT
2023-01-10 18:15:46,226 DEBUG sqlalchemy.pool.impl.NullPool Connection <sqlite3.Connection object at 0x00000286178E9B40> being returned to pool
2023-01-10 18:15:46,227 DEBUG sqlalchemy.pool.impl.NullPool Connection <sqlite3.Connection object at 0x00000286178E9B40> rollback-on-return
2023-01-10 18:15:46,230 DEBUG sqlalchemy.pool.impl.NullPool Closing connection <sqlite3.Connection object at 0x00000286178E9B40>
2023-01-10 18:15:46,239 DEBUG sqlalchemy.pool.impl.NullPool Created new connection <sqlite3.Connection object at 0x00000286178E9940>
2023-01-10 18:15:46,240 DEBUG sqlalchemy.pool.impl.NullPool Connection <sqlite3.Connection object at 0x00000286178E9940> checked out from pool
2023-01-10 18:15:46,241 INFO sqlalchemy.engine.Engine BEGIN (implicit)
2023-01-10 18:15:46,245 INFO sqlalchemy.engine.Engine SELECT recipy.id AS recipy_id, recipy.title AS recipy_title, recipy.author AS recipy_author, recipy.ingredients AS recipy_ingredients, recipy.instructions AS recipy_instructions
FROM recipy
WHERE recipy.id = ?
2023-01-10 18:15:46,246 INFO sqlalchemy.engine.Engine [generated in 0.00101s] (2,)
2023-01-10 18:15:46,248 DEBUG sqlalchemy.engine.Engine Col ('recipy_id', 'recipy_title', 'recipy_author', 'recipy_ingredients', 'recipy_instructions')
2023-01-10 18:15:46,249 DEBUG sqlalchemy.engine.Engine Row (2, 'Omelet', 'Serge', '2 eggs,nmilk, rnolive oil', 'Mix it and fry on the pan')
2023-01-10 18:15:46,253 INFO sqlalchemy.engine.Engine SELECT recipy.id AS recipy_id, recipy.title AS recipy_title, recipy.author AS recipy_author, recipy.ingredients AS recipy_ingredients, recipy.instructions AS recipy_instructions
FROM recipy ORDER BY recipy.title
2023-01-10 18:15:46,254 INFO sqlalchemy.engine.Engine [generated in 0.00130s] ()
2023-01-10 18:15:46,255 DEBUG sqlalchemy.engine.Engine Col ('recipy_id', 'recipy_title', 'recipy_author', 'recipy_ingredients', 'recipy_instructions')
2023-01-10 18:15:46,256 DEBUG sqlalchemy.engine.Engine Row (1, 'Baked apple', 'Serge', 'apple', 'Just bake it')
2023-01-10 18:15:46,256 DEBUG sqlalchemy.engine.Engine Row (2, 'Omelet', 'Serge', '2 eggs,nmilk, rnolive oil', 'Mix it and fry on the pan')
… (10 more similar rows with the content)
<Recipy 2> [<Recipy 1>, <Recipy 2>, <Recipy 4>, <Recipy 10>, <Recipy 12>, <Recipy 14>, <Recipy 13>, <Recipy 9>, <Recipy 8>, <Recipy 7>, <Recipy 5>]
2023-01-10 18:15:46,268 INFO sqlalchemy.engine.Engine ROLLBACK
2023-01-10 18:15:46,269 DEBUG sqlalchemy.pool.impl.NullPool Connection <sqlite3.Connection object at 0x00000286178E9940> being returned to pool
2023-01-10 18:15:46,269 DEBUG sqlalchemy.pool.impl.NullPool Connection <sqlite3.Connection object at 0x00000286178E9940> rollback-on-return
2023-01-10 18:15:46,270 DEBUG sqlalchemy.pool.impl.NullPool Closing connection <sqlite3.Connection object at 0x00000286178E9940>
你写的dbURI是'sqlite:///myDB.db'，这取决于os.getcwd()，当前工作目录。
确保CWD始终相同;或者使用绝对路径名。