10. Django 1.8 Server Build - CentOS 7 hosted on VPS - Views 2 (home page and more templates)

bogotobogo.com site search:

Note

In previous chapter (9. Django 1.8 Server Build - CentOS 7 hosted on VPS - Views (templates and css)), we learned about views via views.py, urls.py, templates, and css.

Home page

We have http://djangotest.sfvue.com/admin and http://djangotest.sfvue.com/cars/, however, we do not have our home page yet:

Here is the modified djangotest/urls.py:

from django.conf.urls import include, url
from django.contrib import admin

urlpatterns = [
   url(r'^admin/', include(admin.site.urls)),
   url(r'^$', 'car.views.index'),
   url(r'^cars/$', 'car.views.CarsAll'),
]

car/views.py:

from django.shortcuts import render_to_response
from django.template import RequestContext
from car.models import Car

def CarsAll(request):
    cars = Car.objects.all().order_by('name')
    context = {'cars': cars}
    return render_to_response('carsall.html',context, context_instance=RequestContext(request))

def index(request):
    return render_to_response('index.html')

The render_to_response(template_name) renders a given template and returns an HttpResponse object with that rendered text.

car/templates/index.html:

{% extends "base.html" %}
{% block content %}
    <a href="cars/">View the Cars list</a>
{% endblock %}

http://djangotest.sfvue.com/ page has a link on the top-left:

If we click the link, we get http://djangotest.sfvue.com/cars/ page:

How Django renders templates

Before we go deep into templates world, let's look at how template gets rendered (The first views).

Django templates are normal Python objects whose constructor expects a string. The placeholders are replaced with the values from a context object.

The following example shows how a dictionary can be used as data structure:

$ python manage.py shell
Python 2.7.5 (default, Jun 17 2014, 18:11:42)
[GCC 4.8.2 20140120 (Red Hat 4.8.2-16)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> from django.template import Context, Template
>>> t = Template('My name is {{ person.first_name }}.')
>>> d = {'person': {'first_name': 'bogotobogo'}}
>>> t.render(Context(d))
u'My name is bogotobogo.'

We can use a Python object as data structure:

>>> class Person: pass
...
>>> p = Person()
>>> p.first_name = 'bogotobogo'
>>> c = Context({'person': p})
>>> t.render(c)
u'My name is bogotobogo.'
>>>

Lists can be used as well:

>>> t = Template('First article: {{ articles.0 }}')
>>> c = Context({'articles': ['bread', 'eggs', 'milk']})
>>> t.render(c)
u'First article: bread'
>>>

templates/carsall.html

We want to list one item per line instead of just printing out all in one line:

{% extends "base.html" %}
{% block content %}
    <div id="carslist">
        {% for car in cars %}
        <p><a href="/cars/{{ car.slug }}">{{ car }}</a></p>
        {% endfor %}
    </div>
{% endblock %}

Note that we used {{ variable }} forms for {{ car.slug }} and {{ car }}. When the template engine encounters a variable, it evaluates that variable and replaces it with the result.

But if we click the link, we get 404 error:

Let's work on displaying specific car item.

car/views.py

We want to make the broken link in the previous section.

from django.shortcuts import render_to_response
from django.template import RequestContext
from car.models import Car

def CarsAll(request):
    cars = Car.objects.all().order_by('name')
    context = {'cars': cars}
    return render_to_response('carsall.html',context, context_instance=RequestContext(request))

def index(request):
    return render_to_response('index.html')

def SpecificCar(request, carslug):
    c = Car.objects.get(slug=carslug)
    context = {'car': c}
    return render_to_response('singlecar.html')

We need to modify urls.py.

djangotest/urls.py

Open djangotest/urls.py and add an url for the specific car item:

from django.conf.urls import include, url
from django.contrib import admin

urlpatterns = [
   url(r'^admin/', include(admin.site.urls)),
   url(r'^$', 'car.views.index'),
   url(r'^cars/$', 'car.views.CarsAll'),
   url(r'^cars/(?P<carslug>.*)/$', 'car.views.SpecificCar'),
]

In Python regular expressions, the syntax for named regular-expression groups is (?P<name>pattern), where name is the name of the group and pattern is some pattern to match.

It passes a variable carslug to car.views.SpecificCar.

templates/singlecar.html

{% extends "base.html" %}
{% block content %}
    <div id="singlecar">
        <p>Name: {{ car }}</p>
        <p>Locality: {{ car.locality }}</p>
        <p>Make: {{ car.make }}</p>
    </div>
{% endblock %}

Now, if we click the link we get a page for the single car item:

Let's make a minor change for the display of locality. In other words, we want "Import" instead of just "I". To see what function we can use, let's use shell:

>>> from car.models import Car
>>> c = Car.objects.get(name='M6 Coupe')
>>> c
<Car: M6 Coupe>
>>> c.slug
u'BMW-M6-F12-Coupe-2015'
>>> dir(c)
['DoesNotExist', 'MultipleObjectsReturned', '__class__', '__delattr__', '__dict__', '__doc__', '__eq__', '__format__', 
'__getattribute__', '__hash__', '__init__', u'__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', 
'__setattr__', '__setstate__', '__sizeof__', '__str__', '__subclasshook__', '__unicode__', '__weakref__', '_base_manager',
 '_check_column_name_clashes', '_check_field_name_clashes', '_check_fields', '_check_id_field', '_check_index_together', 
'_check_local_fields', '_check_long_column_names', '_check_m2m_through_same_relationship', '_check_managers', '_check_model',
 '_check_ordering', '_check_swappable', '_check_unique_together', '_default_manager', '_deferred', '_do_insert', '_do_update',
 '_get_FIELD_display', '_get_next_or_previous_by_FIELD', '_get_next_or_previous_in_order', '_get_pk_val', 
'_get_unique_checks', '_meta', '_perform_date_checks', '_perform_unique_checks', '_save_parents', '_save_table', 
'_set_pk_val', '_state', 'check', 'clean', 'clean_fields', 'date_error_message', 'delete', 'description', 'from_db', 
'full_clean', 'get_deferred_fields', 'get_locality_display', 'id', 'locality', 'make', 'make_id',
 'name', 'objects', 'pk', 'prepare_database_save', 'refresh_from_db', 'save', 'save_base', 'serializable_value', 'slug', 
'unique_error_message', 'validate_unique']
>>> c.get_locality_display()
u'Import'
>>>

So, let's go back to templates/singlecar.html, and modify it:

{% extends "base.html" %}
{% block content %}
    <div id="singlecar">
        <p>Name: {{ car }}</p>
        <p>Locality: {{ car.get_locality_display }}</p>
        <p>Make: {{ car.make }}</p>
    </div>
{% endblock %}

Note that we're not using "()" for get_locality_display in the templates.

Now, if the page is display "Import" rather than just "I":

Getting cars from a specific Makes

Let's get the list of cars from a specific Makes.

Open up car/views.py, and we filter our cars from a given Makes

from django.shortcuts import render_to_response
from django.template import RequestContext
from car.models import Car
from car.models import Make

def CarsAll(request):
    cars = Car.objects.all().order_by('name')
    context = {'cars': cars}
    return render_to_response('carsall.html',context, context_instance=RequestContext(request))

def index(request):
    return render_to_response('index.html')

def SpecificCar(request, carslug):
    c = Car.objects.get(slug=carslug)
    context = {'car': c}
    return render_to_response('singlecar.html', context, context_instance=RequestContext(request))

def SpecificMake(request, makeslug):
    m = Make.objects.get(slug=makeslug)
    cars = Car.objects.filter(make=m)
    context = {'cars': cars}
    return render_to_response('singlemake.html', context, context_instance=RequestContext(request))

Then, urls.py:

from django.conf.urls import include, url
from django.contrib import admin

urlpatterns = [
   url(r'^admin/', include(admin.site.urls)),
   url(r'^$', 'car.views.index'),
   url(r'^cars/$', 'car.views.CarsAll'),
   url(r'^cars/(?P<carslug>.*)/$', 'car.views.SpecificCar'),
   url(r'^makes/(?P<makeslug>.*)/$', 'car.views.SpecificMake'),
]

Then, car/templates/singlemake.html:

{% extends "base.html" %}
{% block content %}
    <div id="carslist">
        <h2>Cars from {{ cars.0.make }}</h2>
        {% for c in cars %}
        <p><a href="/cars/{{ c.slug }}/">{{ c }}</a></p>
        {% endfor %}
    </div>
{% endblock %}

Also, we need to make the make a link in car/templates/singlecar.html:

{% extends "base.html" %}
{% block content %}
    <div id="singlecar">
        <p>Name: {{ car }}</p>
        <p>Locality: {{ car.get_locality_display }}</p>
        <p>Make: <a href="/makes/{{ car.make.slug }}/">{{ car.make }}</a></p>
    </div>
{% endblock %}