Leaning to use forms, mysterious 500 error

Going through the documentation on forms, I’m getting Server Error (500) and I don’t know why. First I wrote some really basic code that works, and then I made a slight mod and it stopped working.

All the code described below is on Github. Below I’ve stripped the comments from it.

The working code

Here are some working views, in polls/views.py. silly_form gets someone’s name, and hands it off to silly_form_process, which changes the name slightly without rendering anything, and then hands it off to silly_form_result, which displays some text including the name.

def silly_form ( request ) :
    return render (
        { 'default_name' : "Replace this text with your name, please." } )

def silly_form_process ( request ):
  your_name = request . POST [ 'your_name' ]
  return HttpResponseRedirect (
    reverse( 'polls:silly-form-result',
             kwargs = { "name_augmented" : "Mr. " + your_name } ) )

def silly_form_result ( request, name_augmented ):
  return render (
      { 'name_augmented' : name_augmented } )

Here are the templates in polls/templates/polls/ used by the above views. They work:

# silly-form.html
<form action="{% url 'polls:silly-form-process'%}" method="post">
    {% csrf_token %}
    <label for="What's your name?">Your name: </label>
    <input id="your_name"
           value="{{ default_name }}">
    <input type="submit" value="OK">

# silly-form-result.html
Hello, {{ name_augmented }}.

Last, here is my working code in urls.py.

# urls.py
  path( 'silly-form/',
        name='silly-form' ),

  path( 'silly-form-process/',
        name='silly-form-process' ),

  path( 'silly-form-result/<name_augmented>/',
        name='silly-form-result' ),

The broken code

The view and template below are based the Django documentation page called Creating forms from models. The changes to urls.py is something I made up, lacking any model to mimic.

I added this view in views.py:

# views.py
def silly_form_2 ( request ):
  if request . method == 'POST':
    form = NameForm ( request . POST )
    if form . is_valid ():
      return HttpResponseRedirect (
          kwargs = { "name_augmented" :
                   "Mr. " + form . cleaned_data . your_name } ) )
  else: form = NameForm()
  return render ( request,
                  { 'form' :  form } )

That uses a new class I had to define in forms.py:

class NameForm ( forms. Form ):
  your_name = forms.CharField(
      label = 'Your name',
      max_length = 100 )

I added this template at polls/templates/polls/silly-form-2.html:

<form action = "{% url 'polls:silly-form-2'%}"
      method = "post">
    {% csrf_token %}
    {{ form }}
    <input type="submit" value="Submit">

I added this to urls.py:

  path( 'silly-form-2/',
        name='silly-form-2' ),

When I visit http://localhost:8000/myapp/polls/silly-form/ (the earlier code), it works, but when I visit http://localhost:8000/myapp/polls/silly-form-2/ all I see is Server Error (500).

The only error message I can find

I believe the only Apache error logs to view are in /var/log/apache2/. There I find three files: access.log error.log other_vhosts_access.log. Tje forst os empty, and the second shows nothing it doesn’t show when things are working normally. The third shows this: - - [31/Oct/2020:01:48:23 +0000] "GET /myapp/polls/silly-form-2/ HTTP/1.1" 500 417 "-" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.89 Safari/537.36" - - [31/Oct/2020:01:48:23 +0000] "GET /favicon.ico HTTP/1.1" 404 490 "http://localhost:8000/myapp/polls/silly-form-2/" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.89 Safari/537.36"

Cleaned data is a dict, not an object.


form . cleaned_data[‘your_name’]

sheepish Now I understand that if debug is false in settings.py, error reports are intended to come through email. I hadn’t set up email notifications so I was being left in the dark. I’ll try to do that. In the meantime setting debug=True works great. (My site is not online yet.)

And of course you were right again, Ken :slight_smile: