Solve the problem of KeyboardInterrupt() error in flask

The reason for the error

KeyboardInterrupt is a common exception in python, which is triggered when the user presses the ctrl c key combination in the terminal . In a flask application, if you press ctrl c while running the application, it will cause the application to throw a KeyboardInterrupt exception and terminate the run.

In this case, this is not an error, but a normal termination of the run. If you want to perform some cleanup in this situation, you can catch the KeyboardInterrupt exception in your application and perform the cleanup there.

If KeyboardInterrupt occurs when you run flask's developmentserver, you can consider using kill in the terminal to terminate it

kill -INT 

In short, this KeyboardInterrupt() is an exception generated when the user terminates the program, and does not require too much care.

How to solve

If you want to do some cleanup operations when terminating the program, you can catch the KeyboardInterrupt exception in your code and perform the cleanup operations there. Here is an example:

try:
app.run()
except KeyboardInterrupt:
# 执行清理操作
pass

This method can perform some cleaning operations when terminating the program, such as closing the file handle, disconnecting the database connection, etc.

In some cases if you are running a program in the background, you may need more ways to terminate the process. You can use ps -ef|grep to get the process id, and then use kill -INT to terminate the program.

In short, if you want to perform some cleanup operations when terminating the program, you can capture the KeyboardInterrupt exception in your code and perform cleanup operations therein, or use the kill command to terminate the program.

Usage Example

Yes, here is an example of closing the database connection when the program terminates:

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////tmp/test.db'
db = SQLAlchemy(app)

@app.route('/')
def hello():
return 'Hello, World!'

try:
app.run()
except KeyboardInterrupt:
# 关闭数据库连接
db.session.close()

Here is an example combined with flask_sqlalchemy. When the user terminates the program, the program will execute db.session.close() to close the database connection

This is just a simple example. In actual applications, you may need Perform more cleanup operations such as closing file handles, disconnecting other connections, etc.

In short, use try except to catch the KeyboardInterrupt exception and perform some cleanup operations when terminating the program, such as closing the connection, etc.

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