恢复已删除的文件

Question

我正在PyCharm IDE中使用python开发一个密码管理器。我正在使用一个数据库来存储密码，从而在项目文件夹中生成一个.db文件。然后我想清除该文件，因为我想使用一个clear db。因此，我从文件夹中删除了.db文件，认为它会创建一个新文件，并且工作正常。但事实并非如此

我收到以下错误消息：

    Traceback (most recent call last):
  File "C:/Users/Gebruiker/PycharmProjects/evault/main.py", line 246, in <module>
    open_vault()
  File "C:/Users/Gebruiker/PycharmProjects/evault/main.py", line 235, in open_vault
    Label(vault, text=(array[i][1]), font=("Helvetica", 12)).place(x=400, y=400)
IndexError: list index out of range

我尝试用本地历史恢复更改，但这对我也不起作用（或者我只是不明白）

[编辑]这可能与正在创建一个新的空数据库有关，然后试图显示该数据库的内容，但由于没有内容而失败？我删除的数据库文件有内容，但没有显示。也可能是完全错误的，idk

如果有帮助，这是我的整个项目代码：

from tkinter import *
from tkinter import messagebox
from random import choice
import array
import sqlite3
import hashlib
import pyperclip as pc
from functools import partial

# Database
with sqlite3.connect("vault.db") as db:
    cursor = db.cursor()

service = None
username = None
password = None

cursor.execute("""
CREATE TABLE IF NOT EXISTS vault (
    id INTEGER PRIMARY KEY, 
    service TEXT NOT NULL, 
    username TEXT NOT NULL, 
    password TEXT NOT NULL);
    """)


def hash_password(pw):
    hash = hashlib.md5(pw)
    hash = hash.hexdigest()

    return hash


def validate_login():
    # getting form data
    uname = username_log.get()
    pwd = master_key.get()
    # applying empty validation
    if uname == '' or pwd == '':
        message.set("Please fill in all the fields")
    else:
        if uname == "Laurens" and pwd == "password":
            login_screen.destroy()
            open_vault()
        else:
            message.set("Wrong username or password")


def generate_password():
    len = 12

    digits = '0123456789'
    chars = 'abcdefghijklmn' \
            'opqrstuvwxyz'
    up = chars.upper()
    special = '_!$%&?'
    all = digits + chars + up + special
    password = ''.join(
        choice(all) for i in range(len)
    )


    # print out password
    print(password)
    save = messagebox.askyesnocancel("Generated password", f"Your generated safe password is: \n \n {password}  "
                                                           f"\n \n Click yes to copy to clipboard"
                                                           f"\n and click no to generate a new password.")
    if save:
        # 'Yes' > copy to clipboard
        pc.copy(password)
    elif not save and save is not None:
        # 'No' > generate new password
        generate_password()
    else:
        # 'Cancel'
        pass


def save_credentials():
    service_input = service.get()
    username_input = username.get()
    password_input = password.get()

    insert_fields = ("""INSERT INTO vault(service, username, password)
    VALUES(?, ?, ?)
    """)

    cursor.execute(insert_fields, (service_input, username_input, password_input))
    db.commit()
    print(db)

    open_vault()


def remove_credentials(input):
    cursor.execute("DELETE FROM vault WHERE id = ?", (input,))
    db.commit()

    open_vault()


def register_credentials():
    global service
    global username
    global password

    vault.destroy()

    register_screen = Tk()
    register_screen.resizable(False, False)
    register_screen.title("Login")
    register_screen.geometry("350x500")
    register_screen.configure(bg='#212121')

    service = StringVar()
    username = StringVar()
    password = StringVar()

    # Service Label
    Label(register_screen, text="Name of service: ", bg='#212121', fg='#ABABAB').place(relx=0.5, y=100, anchor=CENTER)

    # Service textbox
    Entry(register_screen, textvariable=service).place(width=180, height=30, relx=0.5, y=140, anchor=CENTER)

    # Username Label
    Label(register_screen, text="Username: ", bg='#212121', fg='#ABABAB').place(relx=0.5, y=200, anchor=CENTER)

    # Username textbox
    Entry(register_screen, textvariable=username).place(width=180, height=30, relx=0.5, y=240, anchor=CENTER)

    # Password Label
    Label(register_screen, text="Password: ", bg='#212121', fg='#ABABAB').place(relx=0.5, y=300, anchor=CENTER)

    # Password textbox
    Entry(register_screen, textvariable=password).place(width=180, height=30, relx=0.5, y=340, anchor=CENTER)

    # Generate password button
    Button(register_screen, text="Generate safe password", bg='#ABABAB', fg='#000000', command=generate_password).place(
        width=140, height=30, relx=0.5, y=400, anchor=CENTER)

    # Save credentials button
    Button(register_screen, text="Save credentials", bg='#673AB7', fg='#FFFFFF', command=save_credentials).place(
        width=150, height=40, relx=0.5, y=460, anchor=CENTER)

    register_screen.mainloop()


def login_screen():
    global login_screen
    global message
    global username_log
    global master_key

    login_screen = Tk()
    login_screen.resizable(False, False)
    login_screen.title("Login")
    login_screen.geometry("300x210")
    login_screen.configure(bg='#212121')

    # declaring variable
    username_log = StringVar()
    master_key = StringVar()
    message = StringVar()

    # Creating layout of login form
    Label(login_screen, width="300", text="Please enter username and master key", bg="#673AB7", fg="#FFFFFF").pack()

    # Username Label
    Label(login_screen, text="Username: ", bg='#212121', fg='#ABABAB').place(x=20, y=40)

    # Username textbox
    Entry(login_screen, textvariable=username_log).place(x=90, y=42)

    # Password Label
    Label(login_screen, text="Master key: ", bg='#212121', fg='#ABABAB').place(x=20, y=80)

    # Password textbox
    Entry(login_screen, textvariable=master_key, show="*").place(x=90, y=82)

    # Label for displaying login status[success/failed]
    Label(login_screen, text="", textvariable=message, bg='#212121', fg='#ff0000').place(relx=0.5, y=125, anchor=CENTER)

    # Login button
    Button(login_screen, text="Login", width=10, height=1, bg='#673AB7', fg='#FFFFFF', command=validate_login).place(
        x=110, y=150)

    login_screen.mainloop()


def open_vault():
    global vault
    vault = Tk()
    vault.resizable(False, False)
    vault.title("Evault")
    vault.geometry("750x500")
    vault.configure(bg='#212121')

    Label(vault, text="Service", bg='#212121', fg='#ABABAB').place(relx=0.2, y=75)

    Label(vault, text="Username", bg='#212121', fg='#ABABAB').place(relx=0.45, y=75)

    Label(vault, text="Password", bg='#212121', fg='#ABABAB').place(relx=0.7, y=75)

    Button(vault, text="Register new credentials", bg='#673AB7', fg='#FFFFFF', command=register_credentials).place(
        width=150, height=40, relx=0.5, y=450, anchor=CENTER)

    cursor.execute('SELECT * FROM vault')
    if cursor.fetchall() != None:
        i = 0
        while True:
            cursor.execute('SELECT * FROM vault')
            array = cursor.fetchall()

            Label(vault, text=(array[i][1]), font=("Helvetica", 12)).place(x=400, y=400)

            i += 1

            cursor.execute('SELECT * FROM vault')
            if len(cursor.fetchall()) <= i:
                break

    vault.mainloop()


open_vault()

Answer 1

该错误由以下程序引发：

cursor.execute('SELECT * FROM vault')
if cursor.fetchall() != None:
    i = 0
    while True:
        cursor.execute('SELECT * FROM vault')
        array = cursor.fetchall()
        Label(vault, text=(array[i][1]), font=("Helvetica", 12)).place(x=400, y=400)
        i += 1
        cursor.execute('SELECT * FROM vault')
        if len(cursor.fetchall()) <= i:
            break

我承认我不明白这个代码应该做什么。为什么它重复执行同一个查询？你可能想要这样的东西：

cursor.execute("SELECT * FROM vault")
START_HEIGHT=400
LINE_HEIGHT=50
for i, row in enumerate(cursor.fetchall()):
    line_pos = START_HEIGHT + i * LINE_HEIGHT
    Label(vault, text=row[1]).place(x=400,y=line_pos)

也就是说，直接迭代游标返回的行

如果仍然抛出错误，则需要进行一些调试：打印cursor.fetchall()实际返回的内容。（具体来说，如果是迭代器，则打印list(cursor.fetchall())。）