宠物的id在表格中去除，统一使用宠物名字，给出修改后的完整代码

为了将宠物的ID去除并统一使用宠物名字作为唯一标识符，我们需要对数据库表结构和相关代码进行相应的修改。以下是修改后的完整代码：

### 修改后的完整代码

from flask import Flask, render_template, request, redirect, url_for, flash, session
import mysql.connector
import bcrypt
import logging

app = Flask(__name__)
app.secret_key = 'your_secret_key'

# 配置日志
logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(levelname)s - %(message)s')

# 数据库连接
def connect_db():
    conn = mysql.connector.connect(
        host='localhost',
        port=3306,
        user='root',
        password='123456',
        database='pet_weight_management'
    )
    return conn

# 初始化数据库
def init_db():
    conn = connect_db()
    cursor = conn.cursor()
    cursor.execute('''
        CREATE TABLE IF NOT EXISTS users (
            id INT AUTO_INCREMENT PRIMARY KEY,
            username VARCHAR(255) UNIQUE NOT NULL,
            password VARCHAR(255) NOT NULL
        )
    ''')
    cursor.execute('''
        CREATE TABLE IF NOT EXISTS pets (
            pet_name VARCHAR(255) NOT NULL,
            user_id INT NOT NULL,
            PRIMARY KEY (pet_name),
            FOREIGN KEY (user_id) REFERENCES users (id) ON DELETE CASCADE
        )
    ''')
    cursor.execute('''
        CREATE TABLE IF NOT EXISTS pet_weights (
            id INT AUTO_INCREMENT PRIMARY KEY,
            pet_name VARCHAR(255) NOT NULL,
            weight DECIMAL(10, 2) NOT NULL,
            recorded_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
            FOREIGN KEY (pet_name) REFERENCES pets (pet_name) ON DELETE CASCADE
        )
    ''')
    conn.commit()
    conn.close()

@app.route('/')
def index():
    return render_template('index.html')

@app.route('/register', methods=['GET', 'POST'])
def register():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        conn = connect_db()
        cursor = conn.cursor()
        hashed_password = bcrypt.hashpw(password.encode('utf-8'), bcrypt.gensalt())
        try:
            cursor.execute('INSERT INTO users (username, password) VALUES (%s, %s)', (username, hashed_password))
            conn.commit()
            flash("注册成功！", 'success')
            logging.info("用户 %s 注册成功！", username)
            return redirect(url_for('login'))
        except mysql.connector.IntegrityError:
            flash("用户名已存在！", 'warning')
            logging.warning("用户名 %s 已存在！", username)
        finally:
            conn.close()
    return render_template('register.html')

@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        conn = connect_db()
        cursor = conn.cursor()
        cursor.execute('SELECT id, password FROM users WHERE username = %s', (username,))
        result = cursor.fetchone()
        if result and bcrypt.checkpw(password.encode('utf-8'), result[1].encode('utf-8')):
            session['user_id'] = result[0]
            flash("登录成功！", 'success')
            logging.info("用户 %s 登录成功！", username)
            return redirect(url_for('dashboard'))
        else:
            flash("用户名或密码错误！", 'danger')
            logging.warning("用户名或密码错误！")
        conn.close()
    return render_template('login.html')

@app.route('/logout')
def logout():
    session.pop('user_id', None)
    flash("已退出登录。", 'info')
    logging.info("已退出登录。")
    return redirect(url_for('index'))

@app.route('/dashboard')
def dashboard():
    if 'user_id' not in session:
        return redirect(url_for('login'))
    user_id = session['user_id']
    conn = connect_db()
    cursor = conn.cursor()
    cursor.execute('SELECT pet_name FROM pets WHERE user_id = %s', (user_id,))
    pets = cursor.fetchall()
    conn.close()
    return render_template('dashboard.html', pets=pets)

@app.route('/add_pet', methods=['GET', 'POST'])
def add_pet():
    if 'user_id' not in session:
        return redirect(url_for('login'))
    if request.method == 'POST':
        user_id = session['user_id']
        pet_name = request.form['pet_name']
        weight = float(request.form['weight'])
        conn = connect_db()
        cursor = conn.cursor()
        try:
            cursor.execute('INSERT INTO pets (pet_name, user_id) VALUES (%s, %s)', (pet_name, user_id))
            cursor.execute('INSERT INTO pet_weights (pet_name, weight) VALUES (%s, %s)', (pet_name, weight))
            conn.commit()
            flash("宠物添加成功，初始体重为 %.2f kg" % weight, 'success')
            logging.info("宠物 %s 添加成功，初始体重为 %.2f kg", pet_name, weight)
        except mysql.connector.IntegrityError:
            flash("宠物名字已存在！", 'warning')
            logging.warning("宠物名字 %s 已存在！", pet_name)
        finally:
            conn.close()
        return redirect(url_for('dashboard'))
    return render_template('add_pet.html')

@app.route('/view_pet/<string:pet_name>')
def view_pet(pet_name):
    if 'user_id' not in session:
        return redirect(url_for('login'))
    conn = connect_db()
    cursor = conn.cursor()
    cursor.execute('SELECT * FROM pets WHERE pet_name = %s', (pet_name,))
    pet = cursor.fetchone()
    if not pet:
        flash("宠物不存在！", 'warning')
        logging.warning("宠物不存在！")
        return redirect(url_for('dashboard'))
    cursor.execute('SELECT weight, recorded_at FROM pet_weights WHERE pet_name = %s ORDER BY recorded_at', (pet_name,))
    weights = cursor.fetchall()
    conn.close()
    return render_template('view_pet.html', pet=pet, weights=weights)

@app.route('/update_pet_weight/<string:pet_name>', methods=['GET', 'POST'])
def update_pet_weight(pet_name):
    if 'user_id' not in session:
        return redirect(url_for('login'))
    conn = connect_db()
    cursor = conn.cursor()
    # 获取当前宠物的所有体重记录
    cursor.execute('SELECT weight, recorded_at FROM pet_weights WHERE pet_name = %s ORDER BY recorded_at DESC', (pet_name,))
    weights = cursor.fetchall()
    if request.method == 'POST':
        weight = float(request.form['weight'])
        cursor.execute('INSERT INTO pet_weights (pet_name, weight) VALUES (%s, %s)', (pet_name, weight))
        conn.commit()
        flash("宠物体重更新成功！", 'success')
        logging.info("宠物体重更新成功！")
        conn.close()
        return redirect(url_for('view_pet', pet_name=pet_name))
    conn.close()
    return render_template('update_pet_weight.html', pet_name=pet_name, weights=weights)

@app.route('/delete_account', methods=['GET', 'POST'])
def delete_account():
    if 'user_id' not in session:
        return redirect(url_for('login'))
    if request.method == 'POST':
        user_id = session['user_id']
        conn = connect_db()
        cursor = conn.cursor()
        try:
            # 删除宠物的体重记录
            cursor.execute('DELETE FROM pet_weights WHERE pet_name IN (SELECT pet_name FROM pets WHERE user_id = %s)', (user_id,))
            # 删除宠物信息
            cursor.execute('DELETE FROM pets WHERE user_id = %s', (user_id,))
            # 删除用户信息
            cursor.execute('DELETE FROM users WHERE id = %s', (user_id,))
            conn.commit()
            session.pop('user_id', None)
            flash("账号已注销。", 'success')
            logging.info("用户 %s 账号已注销。", user_id)
        except Exception as e:
            flash("注销账号失败: %s" % str(e), 'danger')
            logging.error("注销账号失败: %s", str(e))
        finally:
            conn.close()
        return redirect(url_for('index'))
    return render_template('delete_account.html')

if __name__ == '__main__':
    init_db()
    app.run(debug=True)

### 主要修改点

1. **数据库表结构调整**：
- `pets` 表中去除了 `id` 字段，使用 `pet_name` 作为主键。
- `pet_weights` 表中的 `pet_id` 字段改为 `pet_name`，并将其设置为外键引用 `pets` 表的 `pet_name`。

2. **代码逻辑调整**：
- 在所有涉及宠物的操作中，使用 `pet_name` 替代 `pet_id`。
- 更新 SQL 查询语句以适应新的表结构。

通过这些修改，系统现在可以使用宠物名字作为唯一标识符来管理宠物及其体重记录。