How to solve strange URL ERROR in Django?

Question

I have form like this..

{% extends 'DATAPLO/base.html' %}
{% load staticfiles %}
{% block content %}


<form action="/cholera/SeqData/result_page/" method="post">


    <div style=" color: #1f5a09; margin: auto; margin-top: 10px; height: 15%; border: 1px solid green; box-sizing: border-box;background: #9fc36a; width: 100%">
    <div style= "margin-left:  15px;">
    <p style="color: #000000 "; > <b>Enter year range to explore seqence data country wise</b> </p>
    </div>
    {% csrf_token %}
    <div style= "margin-left:  5px; margin-right: 50px;margin-top: 2px">
    <b>Start year:</b> 
    {{ form.start_year }} 
    </div>
    <div style= "margin-left:  13px; margin-right: 54px;margin-top: 2px">
    <b> End year:</b> 
    {{form.end_year }}  
    </div>
    <div style= "margin-left:  17px; margin-right: 50px;margin-top: 2px">
    <b>Country:</b> 
    {{form.country }} 
    </div>
    <div style= "margin-left:  75.5px; margin-right: 50px;margin-top: 5px">
    <input type="submit" value="Submit"/>
    </div>

</div>
</form>

{% endblock %}

Views like this..

def input_form(request):

    if request.method == 'POST':

        form = InForm(request.POST)
    else:
        form = InForm()

    return render(request, 'SeqData/in_form.html', {'form': form})


def result_page(request):

    form = InForm(request.POST)

    if form.is_valid():

        val1 = form.cleaned_data['start_year']
        val2 = form.cleaned_data['end_year']
        val3 = form.cleaned_data['country']

        if val1 <= val2:
            IDs = SequenceDetails.objects.all().filter(country=val3).filter(year__range =[val1,val2])
            return render(request,'SeqData/slider.html',{'IDs':IDs})

        else:
            return render(request,'SeqData/ERROR.html',{'val1':val1, 'val2':val2})

project URL.py like this..

urlpatterns = [

    url(r'^cholera/', include('table.urls'), name='cholera'),
    url(r'^cholera/', include('DATAPLO.urls')),
    url(r'^cholera/', include('SeqData.urls')),
]

Application URL.py like this..

from django.conf.urls import url
from . import views

urlpatterns = [

url(r'^SeqData/$', views.input_form, name='input_form'),
url(r'', views.result_page, name='result_page'),

]

This code runs perfectly fine when I run this code on local server and submitting year range in form, for example 2001 to 2016 and country name from a drop down example "india", return related data when I clicked submit button and it return a url like given bellow and data table successfully.

127.0.0.1:8000/cholera/SeqData/result_page

When I transfer this code to my VPS and run on apache2 sever every thing works great except, submit button returns a url like given bellow (shown IP is a dummy). and an error page like given bellow.

92.166.167.63/cholera/SeqData/result_page 

Error page..

Page not found (404)
Request Method: POST
Request URL:    http://93.188.167.63/cholera/SeqData/result_page/
Using the URLconf defined in trytable.urls, Django tried these URL patterns, in this order:
^cholera/ ^$ [name='table_list']
^cholera/ ^contact/$ [name='contact']
^cholera/ ^about/$ [name='about']
^cholera/ ^database/$ [name='database']
^cholera/ ^DATAPLO/$ [name='Country_name_list']
^cholera/ ^DATAPLO/(?P<pk>\d+)/$ [name='County_Details']
^cholera/ ^fasta/$ [name='fasta_list']
^cholera/ ^fasta/(?P<pk>\d+)/$ [name='fasta_detail']
^cholera/ ^test_m/$ [name='Student_list']
^cholera/ ^test_m/(?P<pk>\d)/$ [name='Student_info']
^cholera/ ^SeqData/$ [name='input_form']
^cholera/ ^SeqData/$ [name='result']
^cholera/ ^upload_vew/ [name='upload_vew']
^cholera/ ^DataUpload/ [name='DataUpload']
The current URL, cholera/SeqData/result_page/, didn't match any of these.

How could I solve this strange problem please help.. thanks

UPDATE I have change form action like this..

<form action="{% url 'seqdata:result_page' %}" method="post">

and project urls.py like this..

url(r'^cholera/', include('table.urls'), name='cholera'),
url(r'^cholera/', include('DATAPLO.urls')),
url(r'^cholera/', include('SeqData.urls'), namespace='seqdata')

its showing error..

NoReverseMatch at /cholera/SeqData/
u'seqdata' is not a registered namespace

and even form is not opening..

Answer 1

This is you url from form action:

/cholera/SeqData/result_page/

and this is your url from urls.py

url(r'^cholera/', include('SeqData.urls')),
url(r'^$', views.result_page, name='result_page'),

which translates to

/cholera/

As you can see /cholera/SeqData/result_page/ is not in your urls.py .

Change url defined in your form's action attribute to {% url 'result_page' %} as @mohammed-qudah suggested or better yet, define namespace for SeqData and define url with namespace like:

 url(r'^cholera/', include('SeqData.urls', namespace='seqdata'))

and url in action attribute as {% url 'seqdata:result_page' %} .

Overall, what you do there is kind of a bad design. if in input_form() doesn't do anything and You should consider joining both functions into one like this:

def input_form(request):

    if request.method == 'POST':
        form = InForm(request.POST)
        if form.is_valid():
            val1 = form.cleaned_data['start_year']
            val2 = form.cleaned_data['end_year']
            val3 = form.cleaned_data['country']
            if val1 <= val2:
                IDs = SequenceDetails.objects.filter(country=val3).filter(year__range =[val1,val2])
                return render(request,'SeqData/slider.html',{'IDs':IDs})
            else:
                return render(request,'SeqData/ERROR.html',{'val1':val1, 'val2':val2})
    else:
        form = InForm()

    return render(request, 'SeqData/in_form.html', {'form': form})

... and delete attribute action( action="/cholera/SeqData/result_page/" ) from form.

This can be then even further improved by moving val1 <= val2 to form validation so the form will not validate if val1 <= val2 . Relevant part of Django documentation is in subchapter Cleaning and validating fields that depend on each other . Your InForm should then look something like this:

class InForm(forms.ModelForm):
    # Everything as before.
    ...

    def clean(self):
        cleaned_data = super().clean()
        val1 = cleaned_data.get("val1")
        val2 = cleaned_data.get("val2")

        if val1 <= val2:
            raise forms.ValidationError("... this is an error message ...")

You can display this error message in form by calling {{ form.non_field_errors }} . You can check documentation Rendering form error messages for more info. Adjusted input_form() will be something like this:

def input_form(request):

    if request.method == 'POST':
        form = InForm(request.POST)
        if form.is_valid():
            val1 = form.cleaned_data['start_year']
            val2 = form.cleaned_data['end_year']
            val3 = form.cleaned_data['country']
            IDs = SequenceDetails.objects.filter(country=val3).filter(year__range =[val1,val2])
            return render(request,'SeqData/slider.html',{'IDs':IDs})
        else:
            print(form.errors)
    else:
        form = InForm()

    return render(request, 'SeqData/in_form.html', {'form': form})

Answer 2

After strungling a lot I find the answer..

Changed urls like this..

from django.conf.urls import url
from . import views

urlpatterns = [

url(r'^SeqData/$', views.input_form, name='input_form'),
url(r'^SeqData/result_page$', views.result_page, name='result_page'),

]

and as per @Borut suggestion I did this in form.html

<form action="{% url result_page%}" method="post">

And most importantly restart the apache2 to load and implement the changes..

and it worked for me..

thanks