【练习】Python第四次：实现对文件的增删改查

一，实现对

（一），三级菜单的处理结构及退出技巧：使用TAG标记

tag=True
while tag:
    print('leve1')
    choice=input("level1>>: ").strip()
    if choice == 'quit':break
    if choice == 'quit_all': tag = False
    while tag:
        print('level2')
        choice = input("level2>>: ").strip()
        if choice == 'quit': break
        if choice == 'quit_all': tag = False
        while tag:
            print('level3')
            choice = input("level3>: ").strip()
            if choice == 'quit': break
            if choice == 'quit_all': tag = False

（二），查询功能实现

def fetch(data):
    print('这是查询功能')
    print('用户数据是',data)
    backend_data ='backend %s' %data
    with open('haproxy.conf','r') as read_f:
        tag = False #找到标志
        ret =[]
        for read_line in read_f:
            if read_line.strip() == backend_data:#匹配到数据
                tag = True
                continue
            if tag and read_line.startswith('backend'):#到下一个backend停止
                break
            if tag:  #找到后读出后面的数据
                print('%s' %read_line,end ='')
                ret.append(read_line)
    return ret

def add():
    pass

def change():
    pass

def delete():
    pass

#Python文件里面只写不会运行的功能，测试代码在下面写
if __name__ == '__main__':
    msg='''
    1:查询
    2:添加
    3:修改
    4:删除
    5:退出
    '''
    msg_dic ={
        '1':fetch,
        '2':add,
        '3':change,
        '4':delete,
    }

    while True:
        print(msg)
        choice = input('请输入你的选项：').strip()
        if not choice:continue
        if choice == '5':
            break
        data = input('请输入你的数据：').strip()
        res = msg_dic[choice](data)
        print(res)

（三）修改功能实现

import os #os包含改名和删除文件函数
def fetch(data):
    # print('这是查询功能')
    # print('用户数据是',data)
    backend_data ='backend %s' %data
    with open('haproxy.conf','r') as read_f:
        tag = False #找到标志
        ret =[]
        for read_line in read_f:
            if read_line.strip() == backend_data:#匹配到数据
                tag = True
                continue
            if tag and read_line.startswith('backend'):#到下一个backend停止
                break
            if tag:  #找到后读出后面的数据
                print('%s' %read_line,end ='')
                ret.append(read_line)
    return ret

def add():
    pass

# [{'backend':'www.oldboy1.org','record':{'server':'2.2.2.4','weight':20,'maxconn':3000}},{'backend':'www.oldboy1.org','record':{'server':'2.2.2.5','weight':30,'maxconn':4000}}]
def change(data):
    # print('这是修改功能')
    # print('用户输入数据是：',data)
    backend = data[0]['backend'] #从用户传参提取www.oldboy1.org
    backend_line = 'backend %s' %data[0]['backend']#内容：backend www.oldboy1.org

    #拼接字符串old_server_record，把用户传参的源server信息整理出来
    old_server_record = '%sserver %s %s weight %s maxconn %s\n' %(' '*8,data[0]['record']['server'],
                                                                data[0]['record']['server'],
                                                                data[0]['record']['weight'],
                                                                data[0]['record']['maxconn'])
    #用户传参的目标server信息
    new_server_record = '%sserver %s %s weight %s maxconn %s\n' %(' '*8,data[1]['record']['server'],
                                                                data[1]['record']['server'],
                                                                data[1]['record']['weight'],
                                                                data[1]['record']['maxconn'])
    print('用户想要修改的记录是：', old_server_record)
    res = fetch(backend)
    print('来自change函数结果--》',res)

    if not res or old_server_record not in res:
        return '你要修改的记录不存在'
    else:
        index = res.index(old_server_record)
        res[index] = new_server_record

    res.insert(0,'%s\n' %backend_line)
    with open('haproxy.conf','r') as read_f,\
        open('haproxy.conf_new','w') as write_f:
        tag = False
        has_write = False
        for read_line in read_f:
            if read_line.strip() == backend_line:
                tag = True
                continue

            if tag and read_line.startswith('backend'):
                tag = False
            if not tag:
                write_f.write(read_line)
            else:
                if not has_write:
                    for record in res:
                        write_f.write(record)
                has_write = True
    os.rename('haproxy.conf', 'haproxy.conf.bak')
    os.rename('haproxy.conf_new','haproxy.conf')
    os.remove('haproxy.conf.bak')

def delete():
    pass

#Python文件里面只写不会运行的功能，测试代码在下面写
if __name__ == '__main__':
    msg='''
    1:查询
    2:添加
    3:修改
    4:删除
    5:退出
    '''
    msg_dic ={
        '1':fetch,
        '2':add,
        '3':change,
        '4':delete,
    }

    while True:
        print(msg)
        choice = input('请输入你的选项：').strip()
        if not choice:continue
        if choice == '5':
            break
        data = input('请输入你的数据：').strip()
        if choice != '1': #查询输入的是字符串，其他需要处理格式化数据
            data = eval(data)
        res = msg_dic[choice](data)
        print('最终结果是————》',res)