How to debug Flask BuildError

Question

I'm trying to debug a BuildError in a flask 0.8 app. The error occurs in the function personal_open_account() while trying to render part 2 of a multi-step form. Step 1 renders a form, and if it's validated, performs
return redirect(url_for('personal_open_account', step='2')) . That is, it calls itself, but with a new step parameter. Step 1 completes successfully, and the form is validated (I can see a print statement I put in), but I then immediately receive a BuildError:

Traceback (most recent call last):
  File "/Users/sth/.virtualenvs/sb/lib/python2.7/site-packages/flask/app.py", line 1518, in __call__
    return self.wsgi_app(environ, start_response)
  File "/Users/sth/.virtualenvs/sb/lib/python2.7/site-packages/flask/app.py", line 1506, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/Users/sth/.virtualenvs/sb/lib/python2.7/site-packages/flask/app.py", line 1504, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/sth/.virtualenvs/sb/lib/python2.7/site-packages/flask/app.py", line 1264, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Users/sth/.virtualenvs/sb/lib/python2.7/site-packages/flask/app.py", line 1262, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Users/sth/.virtualenvs/sb/lib/python2.7/site-packages/flask/app.py", line 1248, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/Users/sth/dev/sb_flask/sb/views/personal.py", line 333, in personal_open_account
    return redirect(url_for('personal_open_account', step='2'))
  File "/Users/sth/.virtualenvs/sb/lib/python2.7/site-packages/flask/helpers.py", line 208, in url_for
    return ctx.url_adapter.build(endpoint, values, force_external=external)
  File "/Users/sth/.virtualenvs/sb/lib/python2.7/site-packages/werkzeug/routing.py", line 1605, in build
    raise BuildError(endpoint, values, method)
BuildError: ('personal_open_account', {'step': '2'}, None)  

The function itself looks like:

@app.route('/personal/save/<product_type>/<slug>/open-account', methods=['GET', 'POST'])
def personal_open_account(product_type, slug):
...

Answer 1

@app.route('/personal/save/<product_type>/<slug>/open-account'是创建api的错误方法。在这里，您有两个连续的/<product_type>/<slug>/路由器不接受。请尝试改写类似@app.route('/personal/save/<product_type>/slugs/<slug>/open-account'的路由。

Answer 2

从查看代码可以轻松推断出，在随后的调用中没有给出product_id和slug参数。