templates in Django material : Training available at Baabtra

Django framework Training Material

Haris [email protected]/haris.np9twitter.com/np_harisin.linkedin.com/in/harisnp

Courtesy

• www.djangobook.com

Django

• It is a web framework• It follow MVC architecture (MTV architecture)– Model View Controller• Model = Database • View = Presentation• Controller = Business Logic

– Model Template View• Model = Database• Template = Presentation• View = Business Logic

• In the case of Django View contains the business logic. It is different from normal MVC nomenclature.

• For a normal HTML web page to output, there must be four files. – Models.py = It contains the database objects. It helps you

to write python codes rather than SQL statements – View.py = It contains the logic– Ulrs.py = It contains the configuration /urls in the website – Html (template) = The presentation or what the user sees

• a view is just a Python function that takes an HttpRequest as its first parameter and returns an instance of HttpResponse. In order for a Python function to be a Django view, it must do these two things. (There are exceptions, but we’ll get to those later.)

• For creating a new project in Django– django-admin.py startproject mysite

• Create a view.py (It is for easy to understand and naming convention. You can give any name to the py files)

Stupid error that you can make!

• Always tick file extension when you are programming in Windows . I created a file name views.py and in fact it was views.py.py. I kept getting the error – “ ImportError at /hello/– No module named views

• Even though the error is caused while using Django (Python framework), it has nothing to do with Django. You must try importing the views.py directly in the python command line.

• If you get the above error come and check whether .pyc file is created for the view. If not there is something wrong with the file and how it was defined.

“Welcome to baabtra program”

• Here we are going to teach you how to print “Welcome to baabtra – Now the time is [System Time]” using Django framework (Python)

• There will be 2 files required for this program• views.py: This file can be present in Main

folder of the project or in an app.

views.py

• Here baabtrastudentwebsite is the main folder and is a project (studentweb is an app inside the project)

views.py

• import datetime• from django.http import HttpResponse• def hellobaabtra(request):

#This is created for a simple Hello message return HttpResponse("Hello Baabtra")

• def welcomecurrent_datetime(request): now = datetime.datetime.now() html = "<html><body>Welcome to baabttra: It is now

%s.</body></html>" % now return HttpResponse(html)

Urls.py

Running the app

• In the command prompt, type python manage.py runserver

• Type http://127.0.0.1:8000/home/ in the browser

http://127.0.0.1:8000/home/

• Type http://127.0.0.1:8000/homew/ in the browser

http://127.0.0.1:8000/homew/

http://127.0.0.1:8000/homew/

How the code works?

• Django starts with Settings.py file. • When you run python manage.py runserver, the

script looks for a file called settings.py in the inner baabtrastudentwebsite directory. This file contains all sorts of configuration for this particular Django project, all in uppercase: TEMPLATE_DIRS, DATABASES, etc. The most important setting is called ROOT_URLCONF. ROOT_URLCONF tells Django which Python module should be used as the URLconf for this Web site.

• Settings.py

• The autogenerated settings.py contains a ROOT_URLCONF setting that points to the autogenerated urls.py. Below is a screenshot from settings.py

• This corresponds the file /baabtrastudentwebsite/url

• When a request comes in for a particular URL – say, a request for /hello/ – Django loads the URLconf pointed to by the ROOT_URLCONF setting. Then it checks each of the URLpatterns in that URLconf, in order, comparing the requested URL with the patterns one at a time, until it finds one that matches. When it finds one that matches, it calls the view function associated with that pattern, passing it an HttpRequest object as the first parameter.

• In summary:– A request comes in to /hello/.– Django determines the root URLconf by looking at

the ROOT_URLCONF setting.– Django looks at all of the URLpatterns in the URLconf

for the first one that matches /hello/.– If it finds a match, it calls the associated view function.– The view function returns an HttpResponse.– Django converts the HttpResponse to the proper HTTP

response, which results in a Web page.

Templates

• Why templates?– For separating the python code and HTML

• Advantages– Any design change will not affect the python code– Separation of duties

Example for a template<html><head><title>Ordering notice</title></head><body><h1>Baabtra Notification</h1>Dear {{ candidate_name }},Congragulations! You have been selected by {{ company }}.Your subjects are<ul>{% for subject in subjectlist %} <li>{{ subject }}</li>{% endfor %}</ul>{% if distinction %}Great! You have more than 80% marks.{% else %}You have cleared all the tests.{% endif %}Sincerely, {{ mentor }}</body></html>

Explanation

• Candidate_name is a variable. Any text surrounded by a pair of braces (e.g., {{ candidate_name }}) is a variable

• {% if distinction %} is template tag.

How to use template in Django?Type python manage.py shellTemplate system rely on settings.py. Django looks for an environment variable called DJANGO_SETTINGS_MODULE, which should be set to the import path of your settings.py. For example, DJANGO_SETTINGS_MODULE might be set to ‘baabtrastudentwebsite.settings', assuming baabtrastudentwebsite is on your Python path. While running python, it is better to use python manage.py shell as it will reduce errors. You can find the value in manage.py file of the project.

>>> from django import template>>> t = template.Template('My training centre is {{ name }}.')>>> c = template.Context({'name': ‘baabtra'})>>> print t.render(c)My training centre is baabtra.>>> c = template.Context({'name': ‘baabte'})>>> print t.render(c)'My training centre is baabte .

• The second line creates a template object. If there is an error TemplateSyntaxError is thrown.

• Block tag and template tag are synonymous.

Rendering a template

• Values are passed to template by giving it a context. A context is simply a set of template variable names and their associated values. A template uses this to populate its variables and evaluate its tags.

• Context class is present in django.template• Render function returns a unicode object and not a python

string. • We can also pass string as a template argument to the

constructure. For ex. Str_temp ‘My training centre is {{ name }}.‘

• t = template.Template(Str_temp)

• You can render the same template with multiple contexts.

Using Templates in views

• Django provides template-loading API• In the settings.py file, the template directory

name is mentioned under TEMPLATE_DIRS tag.

views.py

• def templatecalling(request): now = datetime.datetime.now()

t = get_template('welcome.html') html = t.render(Context({'current_date': now})) return HttpResponse(html)

Welcome.html

<html><body>Welcome to baabttra: It is now {{ now }}.</body></html>

settings.py

urls.py

http://127.0.0.1:8000/tempex/

• Now if you want to give the relative path, you can follow the below steps:– Settings.py – Please add• import os.path• PROJECT_PATH =

os.path.realpath(os.path.dirname(__file__))

• Now run the application again.

Possible errors

• TemplateDoesNotExist at /tempex/

• If we are not giving the absolute path for the template folder, you need to put the template under the project folder or app with the same name as that of project. Our program runs under the folder with the same name as that of the project.

Refresh the page

• Please note that in this case we have not given the absolute path.

Include Template Tag

• {% include template_name %}• For example, we want to include a home

template in more than one file. In our previous example, we want to create a master page which will be used in two pages.

Problem statement

• Create a master page template which will be included in two templates. The home template will have – This is from master page

• The first and second template will have “This is first template” and “This is second template”

• ViewName: v_baabtrainctemplate1, v_baabtrainctemplate2

• Url Name: url_ baabtrainctemplate1, url_ baabtrainctemplate2

views.py

Solution

• view.py page

views.pydef v_baabtrainctemplate1(request): now = datetime.datetime.now() t = get_template('firstbaabtra.html') html = t.render(Context({'now': now}, {'name':'First Name'})) return HttpResponse(html)

def v_baabtrainctemplate2(request): now = datetime.datetime.now() t = get_template('secondbaabtra.html') html = t.render(Context({'now': now},{'name':'Second Name'})) return HttpResponse(html)

urls.py

templates

• Code under firstbaabtra.html<html><body>{% include "masterpage.html" %} 

This is the first template. Welcome to baabtra: It is now {{ now }}.

</body></html>

• HTML inside masterpage.htmlThere is no html tags used here. This is from master page

Result when run

• The author takes corporate trainings in Android, Java, JQuery, JavaScript and Python. In case if your organization needs training, please connect through www.massbaab.com/baabtra.

• Baabtra provides both online and offline trainings for candidates who want to learn latest programming technologies , frameworks like codeigniter, django, android, iphone app development

• Baabtra also provides basic training in SQL, .NET, PHP, Java and Python who wants to start their career in IT.

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templates in Django material : Training available at Baabtra

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