Selenium登录Canvas网页异常：无法输入账号密码及执行后续操作

脚本可成功打开Chrome浏览器并导航至目标URL，点击“Login”进入登录页面，但停留在登录页，未执行输入账号密码及后续登录操作。

原代码 #

import time
from getpass import getpass
from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support import expected_conditions as EC
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.chrome.service import Service

# Constants
CANVAS_URL = "https://onlinestudy.york.ac.uk"
USERNAME = "<myUsername>"

PASSWORD = "<myPassword"

# Set up Chrome driver
driver_service = Service("<pathToChromedriver>")
driver = webdriver.Chrome(service=driver_service)

# Open Canvas login page
driver.get(f"{CANVAS_URL}")

driver.find_element(By.TAG_NAME, "button").click()

# Wait for the login form to load
WebDriverWait(driver, 10).until(EC.presence_of_element_located((By.ID, "pseudonym_session_unique_id")))

driver.find_element(By.ID, "pseudonym_session_unique_id").send_keys(USERNAME)
driver.find_element(By.ID, "pseudonym_session_password").send_keys(PASSWORD)

# Click the login button on the second page
WebDriverWait(driver, 10).until(EC.element_to_be_clickable((By.TAG_NAME, "button"))).click()

问题排查与修复 #

核心问题 #

1. 语法错误：密码常量PASSWORD = "<myPassword"缺少闭合引号，直接导致代码执行中断，后续操作无法运行。
2. 元素定位不精准：两次使用By.TAG_NAME, "button"定位按钮，页面中可能存在多个按钮，容易匹配到错误元素。
3. 等待条件不合理：使用presence_of_element_located仅确保元素存在于DOM，但元素可能未完全加载可见，导致输入操作失败。

修复后的代码 #

import time
from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support import expected_conditions as EC
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.chrome.service import Service

# Constants
CANVAS_URL = "https://onlinestudy.york.ac.uk"
USERNAME = "<myUsername>"
PASSWORD = "<myPassword>"  # 修复：添加闭合引号

# Set up Chrome driver
driver_service = Service("<pathToChromedriver>")
driver = webdriver.Chrome(service=driver_service)

try:
    # Open Canvas login page
    driver.get(CANVAS_URL)

    # 精准定位初始Login按钮（结合文本与标签）
    WebDriverWait(driver, 10).until(
        EC.element_to_be_clickable((By.XPATH, "//button[contains(text(), 'Login')]"))
    ).click()

    # 等待用户名输入框可见后输入
    username_field = WebDriverWait(driver, 10).until(
        EC.visibility_of_element_located((By.ID, "pseudonym_session_unique_id"))
    )
    username_field.send_keys(USERNAME)

    # 等待密码输入框可见后输入
    password_field = WebDriverWait(driver, 10).until(
        EC.visibility_of_element_located((By.ID, "pseudonym_session_password"))
    )
    password_field.send_keys(PASSWORD)

    # 精准定位登录提交按钮（结合类型与文本）
    WebDriverWait(driver, 10).until(
        EC.element_to_be_clickable((By.XPATH, "//button[@type='submit' and contains(text(), 'Login')]"))
    ).click()
finally:
    # 如需操作完成后自动关闭浏览器，可取消下方注释
    # driver.quit()
    pass

修复说明 #

• 修正了密码变量的语法错误，确保代码能正常执行。
• 所有按钮均使用XPATH精准定位，避免匹配错误元素。
• 改用visibility_of_element_located等待条件，确保元素可见后再执行输入操作，提升稳定性。
• 加入try...finally块，方便管理浏览器资源。

内容的提问来源于stack exchange，提问作者Shaun Potts