Python Flask-Mysql KeyError: 'MYSQL_HOST'答案

【问题标题】：Python Flask-Mysql KeyError: 'MYSQL_HOST'Python Flask-Mysql KeyError: 'MYSQL_HOST'
【发布时间】：2021-09-28 12:08:50
【问题描述】：

我正在构建一个 python flask-Mysql 应用程序。我正在使用 AWS cloud9 构建它。但是当我运行代码时，我得到了 MYSQL_HOST 键错误。我在下面附上代码。是安装错误还是代码错误？`

from flask import Flask, request, render_template
from flask_mysqldb import MySQL


application = Flask(__name__)

application.config['MYSQL_HOST'] = 'localhost'
application.config['MYSQL_USER'] = 'nfhfjfn'
application.config['MYSQL_PASSWORD'] = 'fsfc'
application.config['MYSQL_DB'] = 'fsvf'
application.config['MYSQL_CURSORCLASS'] = 'DictCursor'
mysql = MySQL(application)
# mysql.init_app(application)

application = Flask(__name__)

@application.route("/")
def hello():
    cursor = mysql.connect().cursor()
    cursor.execute("SELECT * from LANGUAGES;")
    mysql.connection.commit()
    languages = cursor.fetchall()
    languages = [list(l) for l in languages]
    return render_template('index.html', languages=languages)
    
    
if __name__ == "__main__":
    application.run(host='0.0.0.0',port=8080, debug=True)

【问题讨论】：

完整的错误信息是什么？它出现在哪一行？
@Marcin 这是最后一行文件“/home/ubuntu/.local/lib/python3.6/site-packages/flask_mysqldb/__init__.py”，第 43 行，如果 current_app. config['MYSQL_HOST']: KeyError: 'MYSQL_HOST'

标签： python amazon-web-services amazon-ec2 flask-mysql

【解决方案1】：

你打电话给application = Flask(__name__)两次。所以第二次你覆盖了第一个application。应该是：

from flask import Flask, request, render_template
from flask_mysqldb import MySQL


application = Flask(__name__)

application.config['MYSQL_HOST'] = 'localhost'
application.config['MYSQL_USER'] = 'nfhfjfn'
application.config['MYSQL_PASSWORD'] = 'fsfc'
application.config['MYSQL_DB'] = 'fsvf'
application.config['MYSQL_CURSORCLASS'] = 'DictCursor'
mysql = MySQL(application)
# mysql.init_app(application)

#application = Flask(__name__) <--- remove that

@application.route("/")
def hello():
    cursor = mysql.connect().cursor()
    cursor.execute("SELECT * from LANGUAGES;")
    mysql.connection.commit()
    languages = cursor.fetchall()
    languages = [list(l) for l in languages]
    return render_template('index.html', languages=languages)
    
    
if __name__ == "__main__":
    application.run(host='0.0.0.0',port=8080, debug=True)

【讨论】：