python - 使用 Flask 蓝图，如果指定了子域，如何修复 url_for 不被破坏？

Question

在 flask 蓝图中，我有:

frontend = Blueprint('frontend', __name__)

我的索引函数的路径是:

@frontend.route('/')
def index():
  #code

这工作正常，但是，我正在尝试向路由添加一个子域，如下所示:

@frontend.route('/', subdomain='<var>')
def index(var):

但这会破坏应用程序并且浏览器会吐出(除其他外):

werkzeug.routing.BuildError
BuildError: ('frontend.index', {}, None)

我的代码在 url_for('frontend.index') 的几个地方调用了 frontend.index

当我包含一个子域时，如何让 url_for 工作？我能找到的文件中唯一我认为可能相关的是 http://flask.pocoo.org/docs/api/ 下的这个:

To integrate applications, Flask has a hook to intercept URL build errors through Flask.build_error_handler. The url_for function results in a BuildError when the current app does not have a URL for the given endpoint and values. When it does, the current_app calls its build_error_handler if it is not None, which can return a string to use as the result of url_for (instead of url_for‘s default to raise the BuildError exception) or re-raise the exception. An example:

def external_url_handler(error, endpoint, **values):
    "Looks up an external URL when `url_for` cannot build a URL."
    # This is an example of hooking the build_error_handler.
    # Here, lookup_url is some utility function you've built
    # which looks up the endpoint in some external URL registry.
    url = lookup_url(endpoint, **values)
    if url is None:
        # External lookup did not have a URL.
        # Re-raise the BuildError, in context of original traceback.
        exc_type, exc_value, tb = sys.exc_info()
        if exc_value is error:
            raise exc_type, exc_value, tb
        else:
            raise error
    # url_for will use this result, instead of raising BuildError.
    return url

app.build_error_handler = external_url_handler

但是，我是 python(和编程)的新手，无法理解将这段代码放在哪里或发生构建错误时如何调用该函数。

任何见解将不胜感激:)

Answer 1

首先，要使用子域，您需要为 SERVER_NAME 设置一个值 configuration :

app.config['SERVER_NAME'] = 'example.net'

你有这样的观点:

frontend = Blueprint('frontend', __name__)
@frontend.route('/', subdomain='<var>')
def index(var):
    return ...

为了重建此 View 的 URL，Flask 需要 var 的值。 url_for('frontend.index') 将失败，因为它没有足够的值。对于上面的 SERVER_NAME，url_for('frontend.index', var='foo') 将返回 http://foo.example.net/。