blocks|key|193189|text|另一种方法是编写|type|unstyled|depth|inlineStyleRanges|entityRanges|data|193190|@user.route('/<user_id>',+defaults={'username':+None})
@user.route('/<user_id>/<username>')
def+show(user_id,+username):
++++pass|code-block|syntax|javascript|193191|但我猜您想要编写一条路由并将username标记为可选？如果是这样的话，我认为这是不可能的。|offset|length|style|CODE|193192|entityMap^0|0|0|E|8|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Another way is to write

<pre><code>@user.route('/&lt;user_id&gt;', defaults={'username': None})
@user.route('/&lt;user_id&gt;/&lt;username&gt;')
def show(user_id, username):
 pass
</code></pre>

But I guess that you want to write a single route and mark <code>username</code> as optional? If that's the case, I don't think it's possible.

blocks|key|193208|text|与几个月前开发的Audrius几乎相同，但您可能会发现，使用函数头中的默认值会更具可读性-就像您习惯使用python的方式一样：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|193209|@app.route('/<user_id>')
@app.route('/<user_id>/<username>')
def+show(user_id,+username='Anonymous'):
++++return+user_id+%2B+':'+%2B+username|code-block|syntax|javascript|193210|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Almost the same as Audrius cooked up some months ago, but you might find it a bit more readable with the defaults in the function head - the way you are used to with python:

<pre><code>@app.route('/&lt;user_id&gt;')
@app.route('/&lt;user_id&gt;/&lt;username&gt;')
def show(user_id, username='Anonymous'):
 return user_id + ':' + username
</code></pre>

blocks|key|193216|text|从Flask+0.10开始，您不能将多个路由添加到一个端点。但是你可以添加假的端点|type|unstyled|depth|inlineStyleRanges|entityRanges|data|193217|@user.route('/<userId>')
def+show(userId):
+++return+show_with_username(userId)

@user.route('/<userId>/<username>')
def+show_with_username(userId,username=None):
+++pass|code-block|syntax|javascript|193218|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Since Flask 0.10 you can`t add multiple routes to one endpoint. But you can add fake endpoint

<pre><code>@user.route('/&lt;userId&gt;')
def show(userId):
 return show_with_username(userId)

@user.route('/&lt;userId&gt;/&lt;username&gt;')
def show_with_username(userId,username=None):
 pass
</code></pre>

blocks|key|411358|text|如果你像我一样使用Flask-Restful，也可以这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|411359|api.add_resource(UserAPI,+'/<userId>',+'/<userId>/<username>',+endpoint+=+'user')|code-block|syntax|javascript|411360|A然后在你的Resource类中：|411361|class+UserAPI(Resource):

++def+get(self,+userId,+username=None):
++++pass|411362|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

If you are using Flask-Restful like me, it is also possible this way:

<pre><code>api.add_resource(UserAPI, '/&lt;userId&gt;', '/&lt;userId&gt;/&lt;username&gt;', endpoint = 'user')
</code></pre>

a then in your Resource class:

<pre><code>class UserAPI(Resource):

 def get(self, userId, username=None):
 pass
</code></pre>

blocks|key|193227|text|@user.route('/<userId>/')++#+NEED+'/'+AFTER+LINK
@user.route('/<userId>/<username>')
def+show(userId,+username=None):
++++pass|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|193228|https://flask.palletsprojects.com/en/1.1.x/quickstart/#unique-urls-redirection-behavior|unstyled|offset|length|193229|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|2F|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|Q|8|@]|9|@$G|R|H|S|1|T]]|A|$]]|$1|I|3|-4|5|F|7|U|8|@]|9|@]|A|$]]]|J|$K|$5|L|M|N|A|$O|E]]]]

<pre><code>@user.route('/&lt;userId&gt;/') # NEED '/' AFTER LINK
@user.route('/&lt;userId&gt;/&lt;username&gt;')
def show(userId, username=None):
 pass
</code></pre>

<a href="https://flask.palletsprojects.com/en/1.1.x/quickstart/#unique-urls-redirection-behavior" rel="noreferrer">https://flask.palletsprojects.com/en/1.1.x/quickstart/#unique-urls-redirection-behavior</a>

blocks|key|411369|text|@app.route('/',+defaults={'path':+''})
@app.route('/<+path:path+>')
def+catch_all(path):
++++return+'You+want+path:+%25s'+%25+path|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|411370|http://flask.pocoo.org/snippets/57/|unstyled|offset|length|411371|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|Z|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|Q|8|@]|9|@$G|R|H|S|1|T]]|A|$]]|$1|I|3|-4|5|F|7|U|8|@]|9|@]|A|$]]]|J|$K|$5|L|M|N|A|$O|E]]]]

<pre><code>@app.route('/', defaults={'path': ''})
@app.route('/&lt; path:path &gt;')
def catch_all(path):
 return 'You want path: %s' % path
</code></pre>

<a href="http://flask.pocoo.org/snippets/57/" rel="noreferrer">http://flask.pocoo.org/snippets/57/</a>

blocks|key|411373|text|@user.route('/<user_id>',+defaults={'username':+default_value})
@user.route('/<user_id>/<username>')
def+show(user_id,+username):
+++#
+++pass|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|411374|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>@user.route('/&lt;user_id&gt;', defaults={'username': default_value})
@user.route('/&lt;user_id&gt;/&lt;username&gt;')
def show(user_id, username):
 #
 pass
</code></pre>

blocks|key|411389|text|我认为你可以使用Blueprint，这会让你的代码看起来更好更整洁。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|411390|示例：|411391|from+flask+import+Blueprint

bp+=+Blueprint(__name__,+"example")

@bp.route("/example",+methods=["POST"])
def+example(self):
+++print("example")|code-block|syntax|javascript|411392|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

I think you can use Blueprint and that's will make ur code look better and neatly.

example:

<pre><code>from flask import Blueprint

bp = Blueprint(__name__, "example")

@bp.route("/example", methods=["POST"])
def example(self):
 print("example")
</code></pre>

blocks|key|193295|text|我知道这篇文章真的很老了，但是我开发了一个叫做flask_optional_routes的包。代码位于：https://github.com/sudouser2010/flask_optional_routes。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|193296|from+flask+import+Flask

from+flask_optional_routes+import+OptionalRoutes


app+=+Flask(__name__)
optional+=+OptionalRoutes(app)

@optional.routes('/<user_id>/<user_name>?/')
def+foobar(user_id,+user_name=None):
++++return+'it+worked!'

if+__name__+==+"__main__":
++++app.run(host='0.0.0.0',+port=5000)|code-block|syntax|javascript|193297|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/sudouser2010/flask_optional_routes^0|1G|1H|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

I know this post is really old but I worked on a package that does this called flask_optional_routes. The code is located at: <a href="https://github.com/sudouser2010/flask_optional_routes" rel="nofollow noreferrer">https://github.com/sudouser2010/flask_optional_routes</a>. 

<pre><code>from flask import Flask

from flask_optional_routes import OptionalRoutes


app = Flask(__name__)
optional = OptionalRoutes(app)

@optional.routes('/&lt;user_id&gt;/&lt;user_name&gt;?/')
def foobar(user_id, user_name=None):
 return 'it worked!'

if __name__ == "__main__":
 app.run(host='0.0.0.0', port=5000)
</code></pre>

blocks|key|193323|text|几乎与skornos相同，但使用了变量声明以获得更明确的答案。它可以与Flask-RESTful+extension一起工作|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|193324|from+flask+import+Flask
from+flask_restful+import+Resource,+Api

app+=+Flask(__name__)
api+=+Api(app)

class+UserAPI(Resource):
++++def+show(userId,+username=None):
++++pass

api.add_resource(UserAPI,+'/<userId>',+'/<userId>/<username>',+endpoint='user')

if+__name__+==+'__main__':
++++app.run()|code-block|syntax|javascript|193325|add_resource方法允许传递多个URL。每一个都会被路由到你的Resource。|style|CODE|193326|entityMap|0|LINK|mutability|MUTABLE|url|https://flask-restful.readthedocs.io/en/latest/|1|https://flask-restful.readthedocs.io/en/latest/api.html#flask_restful.Resource^0|Z|N|0|0|0|0|C|Z|8|1|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@$A|X|B|Y|1|Z]]|C|$]]|$1|D|3|E|5|F|7|10|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|11|8|@$A|12|B|13|K|L]]|9|@$A|14|B|15|1|16]]|C|$]]|$1|M|3|-4|5|6|7|17|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]|U|$5|P|Q|R|C|$S|V]]]]

Almost the same as skornos, but with variable declarations for a more explicit answer. It can work with <a href="https://flask-restful.readthedocs.io/en/latest/" rel="noreferrer">Flask-RESTful extension</a>:

<pre class="lang-py prettyprint-override"><code>from flask import Flask
from flask_restful import Resource, Api

app = Flask(__name__)
api = Api(app)

class UserAPI(Resource):
 def show(userId, username=None):
 pass

api.add_resource(UserAPI, '/&lt;userId&gt;', '/&lt;userId&gt;/&lt;username&gt;', endpoint='user')

if __name__ == '__main__':
 app.run()
</code></pre>

The <code>add_resource</code> method allows pass multiples URLs. Each one will be routed to your <a href="https://flask-restful.readthedocs.io/en/latest/api.html#flask_restful.Resource" rel="noreferrer">Resource</a>.

Is it possible to directly declare a flask URL optional parameter?

Currently I'm proceeding the following way:

<pre><code>@user.route('/&lt;userId&gt;')
@user.route('/&lt;userId&gt;/&lt;username&gt;')
def show(userId, username=None):
 pass
</code></pre>

How can I directly say that <code>username</code> is optional?

Can Flask have optional URL parameters?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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是否可以直接声明flask URL可选参数？目前，我正在进行以下操作：@user.route('/<userId>')@user.route('/<userId>/<username>')def show(userId, username=None): pass我怎么能直接说username是可选的呢？

问Flask可以有可选的URL参数吗？
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问Flask可以有可选的URL参数吗？EN