Python flask - "Check if the username exists in the MySQL database"

Question

我正在运行一个 python Flask 应用程序，它需要用户名和密码。我想检查Mysql数据库中是否存在该用户名。如果是的话，我想在网页上返回“用户名存在”。

下面是我的 flask 代码:

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

app = Flask(__name__)

db = yaml.load(open('db.yaml'))
app.config['MYSQL_HOST'] = db['mysql_host']
app.config['MYSQL_USER'] = db['mysql_user']
app.config['MYSQL_PASSWORD'] = db['mysql_password']
app.config['MYSQL_DB'] = db['mysql_db']

mysql =MySQL(app)

@app.route('/', methods=['GET','POST'])
def index():

    if request.method == 'POST' and request.method=='GET':
        #fetch form data
        userdetails = request.form
        name = userdetails['name']
        email = userdetails['email']
        cur = mysql.connection.cursor()
        new_value= cur.execute("SELECT (name,email) FROM users where name = %s and email=%s",'name','email')
        if new_value> 0:
            return "the username exists"
        else:
            return "SUCCESS!,Successfully entered into the Database"

    return render_template('index.html')

<小时/>

当我运行 Flask 应用程序时，我的网页不返回任何内容。

Answer 1

好吧，所以我无法发表评论，因为我没有足够的声誉，但是要获取表单数据，request.method 需要是POST，因为这是用户点击的时候提交表单的按钮。正如 Brian Driscoll 所说，request.method 不能同时是 POST 和 GET，就像说:

if bob.age == 15 and bob.age == 50 

bob 不能同时是 15 岁和 50 岁，同样，request.method 不能是 POST 和 GET同时。所以你想做的是

if request.method == 'POST':
        userdetails = request.form
        name = userdetails['name']
        email = userdetails['email']
        cur = mysql.connection.cursor()
        new_value= cur.execute("SELECT (name,email) FROM users where name = %s and email=%s",'name','email')
        if new_value> 0:
            return "the username exists"
        else:
            return "SUCCESS!,Successfully entered into the Database"

有关POST、GET和其他请求的更多信息，您可以引用文章here