15(c). Let us understand what we wrote in edit_contact.html in django project(Very Important)

let us consider this..... ie., 

<form action="{% url 'contacts-new' %}"

so  here we are using tags in the action attribute.  that is ....

{% url 'contacts-new' %}

{%url%} is the template tags ok 

then what is this contacts-new means  where it is going......

let us see url.py........

url.py

=====

from django.conf.urls import patterns, include, url
from login.views import hello_page, home
from django.contrib import admin

admin.autodiscover()


import contacts.views


urlpatterns = patterns('',
    # Examples:
    # url(r'^$', 'btms.views.home', name='home'),
    # url(r'^blog/', include('blog.urls')),

   # url(r'^admin/', include(admin.site.urls)),
    url(r'^$', hello_page),
    url(r'^home/', home),
    url(r'^view/',contacts.views.ListContactView.as_view(),name='contacts-list',),
    url(r'^new$', contacts.views.CreateContactView.as_view(), name='contacts-new',),



)

so in the url.py we added the  

 url(r'^new$', contacts.views.CreateContactView.as_view(), name='contacts-new',),

pattern        : ^new$

include file   : contacts.views.CreateContactView.as_view()

name           : contacts-new

so in the include file let see what is happening ....... ie., 

contacts(app)   =>   view.py   =>  CreateContactView =>  as_view()(this is functionality to view)

View.py 

======== 

from django.views.generic import ListView
from contacts.models import Contact
from django.core.urlresolvers import reverse
from django.views.generic import CreateView


class ListContactView(ListView):
      model=Contact
      template_name = 'contact_list.html'

class CreateContactView(CreateView):
      model = Contact
      template_name = 'edit_contact.html'
      
      def get_success_url(self):
          return reverse('contacts-list')

 --------------------------- so that is fine

so let see more ie, 

{% csrf_token %}

  <ul>
  {{ form.as_ul }}

  </ul>
<input id='save_contact' type="submit" value="save"/>

    
</form> 

so in these what is 

 {% csrf_token %} ?????????????

csrf=

Cross Site Request Forgery protection

 After more investigation it appears the {% csrf_token %} is

 always inserted if the form has method post and not if it doesn't.

 Very clever auto protection from Django.

ie., 

<form action="{% url 'contacts-new' %}" method="post"> 

so better to use ....

------------------- next what we will see 

<ul>
  {{ form.as_ul }}

  </ul>

let us know what is these actually doing .... ie.,

  {{ form.as_ul }} ???????????

in the output....... 

ie., 


 

i did not wrote the input box for every column ie., first name,, last name,, father name and email...

so when i given that in {{ form.as_ul}} i am getting that in unordered list becuase it is there in 

between <ul> tag ....

so how it is happening.....

let us think what actually it is happens....

so .....  

 let us take  files ie., 

edit_contact.html ,model.py , url.py and view.py

edit_contact.html

=================

<h1>add contact</h1>
<form action="{% url 'contacts-new' %}" method="post">
  {% csrf_token %}

  <ul>
  {{ form.as_ul }}

  </ul>
<input id='save_contact' type="submit" value="save"/>

    
</form>
<a href="{% url 'contacts-list' %}">back to list</a>

 View.py ======== from django.views.generic import ListView
from contacts.models import Contact
from django.core.urlresolvers import reverse
from django.views.generic import CreateView


class ListContactView(ListView):
      model=Contact
      template_name = 'contact_list.html'

class CreateContactView(CreateView):
      model = Contact
      template_name = 'edit_contact.html'
      
      def get_success_url(self):
          return reverse('contacts-list')

in model file we have four column ie., 

 model.py

=========

 from django.db import models

class Contact(models.Model):
    first_name = models.CharField(
        max_length=255,
    )
    last_name = models.CharField(
        max_length=255,

    )

    father_name = models.CharField(
        max_length=255,

    )

    email = models.EmailField()
   

    def __str__(self):

        return ' '.join([
            self.first_name,
            self.last_name,
        ])

 url.py

=======

from django.conf.urls import patterns, include, url
from login.views import hello_page, home
from django.contrib import admin

admin.autodiscover()


import contacts.views


urlpatterns = patterns('',
    # Examples:
    # url(r'^$', 'btms.views.home', name='home'),
    # url(r'^blog/', include('blog.urls')),

   # url(r'^admin/', include(admin.site.urls)),
    url(r'^$', hello_page),
    url(r'^home/', home),
    url(r'^view/',contacts.views.ListContactView.as_view(),name='contacts-list',),
    url(r'^new$', contacts.views.CreateContactView.as_view(), name='contacts-new',),



) 

flow steps

===========

-> so when i write {{form.as_url }} 
-> it is searching from action url ie., contact-new

-> so it will check through url.py..for contact-new... ie., 

  url(r'^new$', contacts.views.CreateContactView.as_view(), name='contacts-new',),

-> so it will go to contact---->  view  --->  CreateContactView ---->

and search for model name....... ie., 
  model = Contact

->so in model.py ----> class Contact(models.Model): --> it will send the column name what ever it have...

-> so coming to this example it will have 4 column ie., first name,last name,father name and email...

-> that column are appear with respect data type for example .... i am writing .... email as something.... without proper pattern,,,,

so i am getting error becuase model is sending the datatype also..... so it will take default validation....... ....it is great na..

Advantage of {{form.as_ul}}

=================

it is avoiding the html work... and validation for basic that is the result ....all are saying it is easy to develop compare to other......

----------------------------------- next we will see

<a href="{% url 'contacts-list' %}">back to list</a>

this is anchor tag  but in href see once again we use template tags......

so with this no need to write the complete path like 

<a href="127.0.0.1:8080/view"> back to list</a>

if we change the ip address we need to change all......

so it will become more work.... to avoid these 

django is using template tags..... great .....