赋值 json 之前引用的局部变量

Question

在几个小时内一切正常，然后我会收到这个错误，它会停止运行。

todolist_items = len(todoalso)
UnboundLocalError: local variable 'todoalso' referenced before assignment

我认为这是我遇到问题的部分，但我不明白为什么。

    response = requests.get("https://beta.todoist.com/API/v8/tasks", params={"token":todoist_TOKEN})
if response.status_code == 200:
    todoalso = response.json()
global todolist_items
todolist_items = len(todoalso)

Answer 1

您需要捕获响应失败的情况，并将其记录下来以查看原因。

if response.status_code == 200:
    todoalso = response.json()
else:
    todoalso = None
    print response.status_code,response

Answer 2

我会比其他人更进一步并建议：

response = requests.get("https://beta.todoist.com/API/v8/tasks", params={"token":todoist_TOKEN})
global todolist_items

if response.status_code == 200:
    todoalso = response.json()
    # Let's assign this variable here, where we know that the status code is 200
    todolist_items = len(todoalso)
else:
    # instead of simply assigning the value "None" to todoalso, let's return the response code if it's not 200, because an error probably occurred
    print response.status_code

Answer 3

这种情况下我会认为响应码不是200，所以直接去

todolist_items = len(todoalso)

在 if 分支中没有赋值。 或许修改成这样会更好

    response = requests.get("https://beta.todoist.com/API/v8/tasks", params={"token":todoist_TOKEN})
if response.status_code == 200:
    todoalso = response.json()
    global todolist_items
    todolist_items = len(todoalso)

根据@ResetACK 的建议，我添加了一些更改

    response = requests.get("https://beta.todoist.com/API/v8/tasks", params={"token":todoist_TOKEN})
if response.status_code == 200:
    todoalso = response.json()
    global todolist_items
    todolist_items = len(todoalso)
else:
    requests.raise_for_status()