NameError：在我的表單中未定義名稱“用戶名”

Question

@app.route('/register/go', methods=['GET', 'POST'])
def register():
    global username, password, email
    if request.method == 'POST' and 'username' in request.form and 'password' in request.form:
        # Create variables for easy access
        username = request.form['username']
        password = request.form['password']
        email = request.form['email']

    cursor.execute('SELECT * FROM accounts WHERE username = %s', [username])
    account = cursor.fetchone()
    if account:
        cursor.execute('INSERT INTO accounts VALUES(NULL,%s, %s, %s)', [username, password, email])
        connection.commit()
        msg = 'success'

    # Show registration form with message (if any)
    return render_template('register.html')

我持續收到以下代碼行的錯誤，因為“ NameError：未定義名稱'用戶名'”

cursor.execute('SELECT * FROM accounts WHERE username = %s', [username])

Answer 1

即使您將username為全局，也需要為其賦予一個值。 用這個：

username = ''
global username

Answer 2

如果if條件失敗， if不會設置該變量。 但是，如果不填寫表單，則根本不應該將其插入數據庫。 您應該將該代碼移至if塊中。

另外，您的if account條件是向后的。 如果該帳戶尚不存在，則只應插入一行。

@app.route('/register/go', methods=['GET', 'POST'])
def register():
    global username, password, email
    if request.method == 'POST' and 'username' in request.form and 'password' in request.form:
        # Create variables for easy access
        username = request.form['username']
        password = request.form['password']
        email = request.form['email']

        cursor.execute('SELECT * FROM accounts WHERE username = %s', [username])
        account = cursor.fetchone()
        if account:
            msg = 'username already taken'
        else:
            cursor.execute('INSERT INTO accounts VALUES(NULL,%s, %s, %s)', [username, password, email])
            connection.commit()
            msg = 'success'
    else:
        msg = 'Username and password are required'

    # Show registration form with message (if any)
    return render_template('register.html')