raise MultiValueDictKeyError(key) with POST VXML

Question

I get the following error raise MultiValueDictKeyError(key) : django.utils.datastructures.MultiValueDictKeyError: 'redirect' when I try to save the value the user types in.

At first, I thought it had something to do with the input value, but since the error explicitly gives 'redirect' back I assume it has something to do with the redirect to the next part of the application. I have tried two different versions of return redirect, but it is very confusing what now exactly the right thing is.

At the same time, I get raise NoReverseMatch(msg) when I try to submit the input value to the database.

view

def InputData(request, element_id, session_id):
    input_element = get_object_or_404(InputData_model, pk=element_id)
    voice_service = input_element.service
    session = lookup_or_create_session(voice_service, session_id)

    if request.method == "POST":
        session = get_object_or_404(CallSession, pk=session_id)
        value = 'DTMF_input'
        result = UserInput()
        result.input_value = request.POST.get('input_value')
        result.session = session
        result.category = input_element.input_category 
        result.save()

        return redirect(request.POST['redirect'])

template

<form id="input_form">
  <property name="interdigittimeout" value="2s"/>
 <property name="timeout" value="4s"/>
 <property name="termchar" value="#" />
  <field name="input_value" type="digits?minlength=1;maxlength=5">
    <prompt>
     <audio src="{{ ask_input_label }}"/>
    </prompt>

    <filled>

     <assign name="redirect" expr="'{{ redirect_url }}'"/>
     <submit next="{{ url }}" enctype="multipart/form-data" namelist="input_value" method="post"/>
     <goto next="{{ redirect_url }}" />
    </filled>
  </field>
</form>

traceback

Internal Server Error: /vxml/InputData/33/57
File "/app/.heroku/python/lib/python3.6/site-packages/django/utils/datastructures.py", line 77, in __getitem__
list_ = super().__getitem__(key)
KeyError: 'redirect'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/handlers/exception.py", line 34, in inner
response = get_response(request)
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/handlers/base.py", line 126, in _get_response
response = self.process_exception_by_middleware(e, request)
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/handlers/base.py", line 124, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/app/vsdk/service_development/views/vse_input.py", line 55, in InputData
return redirect(request.POST['redirect'])
File "/app/.heroku/python/lib/python3.6/site-packages/django/utils/datastructures.py", line 79, in __getitem__
raise MultiValueDictKeyError(key)
django.utils.datastructures.MultiValueDictKeyError: 'redirect'
Internal Server Error: /vxml/InputData/33/57
Traceback (most recent call last):
File "/app/.heroku/python/lib/python3.6/site-packages/django/utils/datastructures.py", line 77, in __getitem__
list_ = super().__getitem__(key)
KeyError: 'redirect'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/handlers/exception.py", line 34, in inner
response = get_response(request)
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/handlers/base.py", line 126, in _get_response
response = self.process_exception_by_middleware(e, request)
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/handlers/base.py", line 124, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/app/vsdk/service_development/views/vse_input.py", line 55, in InputData
return redirect(request.POST['redirect'])
File "/app/.heroku/python/lib/python3.6/site-packages/django/utils/datastructures.py", line 79, in __getitem__
raise MultiValueDictKeyError(key)
django.utils.datastructures.MultiValueDictKeyError: 'redirect'
10.33.126.112 - - [29/Apr/2019:19:47:02 +0200] "POST /vxml/InputData/33/57 HTTP/1.1" 500 67237 "http://petrichor-rain-system.herokuapp.com/vxml/InputData/33/57" "Voxeo-VXML/16.0.4.5.89134"

Conclusion, I am completely confused with all the errors I get on this code and I don't know what to do anymore. Would someone want to help me make this work?

Answer 1

To help you understand these error traces, the usual way to look at them is this:

1. Search for the line(s) that refer to files that are part of your own code:

   • So File "/app/vsdk/service_development/views/vse_input.py"
   • Not File "/app/.heroku/python/lib/python3.6/site-packages/django/core/handlers/base.py" or any line within the python3.6/site-packages folders

   In this case there's only one line of your code, so that's easy. If there are multiple lines, the one most at the bottom is where to start.

2. Look at the location of the error:

   • line 55, in InputData
   • return redirect(request.POST['redirect'])

   That tells you exactly where the exception is raised

3. Look at the exception: django.utils.datastructures.MultiValueDictKeyError: 'redirect'. This tells you more about what's wrong. KeyError means the key doesn't exist in the dictionary. Here we have a special type of dictionary (keys can have multiple values). But basically the meaning is: this key ("redirect") doesn't exist, so I cannot access it.

If you print(request.POST.get('redirect')) you'll see it's None.