**kwargs 无法识别密钥 'table' - python 3.5

Question

我在 **kwarg 中的 kwarg table 在我调用它时无法识别。

class Database():
    def set_db_setting(self, host, username, passwd, database):
        try:
            self.host = host
            self.username = username
            self.passwd = passwd
            self.database = database
            self.db = pymysql.connect(host=host, user=username, passwd=passwd, db=database)
            print('connected to: {}'.format(database))
            return self.db
        except:
            print('\nerror connecting to database\n')

    def db_select(self, *selected_fields, **kwargs):
        self.selected_fields = selected_fields = list(selected_fields)
        self.table = (kwargs['table']
                      if 'table' in kwargs 
                      else selected_fields.pop())
        try:
            with self.db.cursor() as cursor:
                sql_tld_id_query = Database.query_stmt_list[0]+ ', '.join(selected_fields) + Database.query_stmt_list[4] + table + Database.query_stmt_list[5] + where_field + '=' + 'www.website.com'
                print("sql_tld_id_query is {}".format(sql_tld_id_query))
        except Exception as gatherid_err:
            print("exception was {}".format(gatherid_err))
            self.db.rollback()

I'm invoking it like:

    dbclass = Database()
    dbclass.set_db_setting('localhost', 'root', 'password', 'garbagedb')
    dbclass.db_select('id', 'name', table='tld', where_field='name')

我收到如下错误：

name 'table' is not defined

完整回溯 通过以下方式调用：

import traceback
traceback.print_stack()

`

  File "dbcrud.py", line 56, in <module>
    dbclass.db_select('id', 'name', table='tld', where_field='name')
  File "dbcrud.py", line 31, in db_select
    traceback.print_stack()
self.selected_fields is ['id', 'name']
exception was name 'table' is not defined

我做错了什么？

Answer 1

我添加了续行以使其水平对齐...

sql_tld_id_query = Database.query_stmt_list[0]+ ', '.join(selected_fields) + \
Database.query_stmt_list[4] + <b>table</b> + Database.query_stmt_list[5] + \
where_field + '=' + 'www.website.com'

粗体的table应该是self.table

你盲目地用 try except Exception 块捕获所有异常，这可能对你隐藏了真正的问题。最好找出您要捕获的特定类型的异常，然后只过滤掉它们。例如，如果我想要一个计算器程序在用户尝试除以零时不会崩溃，我会使用 try: ... except ZeroDivisionError as e: ...

**kwargs 无法识别密钥 'table' - python 3.5

**kwargs not recognizing key 'table' - python 3.5

python

keyword-argument

python-3.x

python-3.5