LXF108:Django

# -*- Coding: utf-8 -*-

"" "

>>> From news.models import News

>>> From datetime import datetime

>>> News = News (title = "Title", description = "Description", pub_date = datetime.now (), text = "text")

>>> News.save ()

>>> News = News.objects.get (pk = 1)

>>> Print news.title.encode ('utf-8')

 Title

"" "

</ Source>

In line 1 encoding, but since the third is very

test. Note that each line begins with three characters "more" (>>>), in the interactive mode, Python. Line 10

These characters do not, because it contains the expected output

print from line 9.

[[Image: LXF108 85 1.png | thumb | 200px | Fig. 1. Test passed successfully!]]

Before running the test, you need to add in settings.py

line

 TEST_DATABASE_CHARSET = "UTF8"

to file encoding and the database match. Before performing the test, Django will create a special auxiliary databases, so

the user specified in settings.DATABASE_USER, must have

the appropriate authority. To begin testing, type:

 python manage.py test news

after which you will see something that shows

Fig. 1.

Messages similar to appear during the creation of tables

when you first install, but now it happens in a test database. In

end shows the number of tests performed, their results and

notified about the destruction of a test material. We checked our

application (news), but, as you know, Django provides a few

own applications and representations (eg, "admin") -

and they also supplied with their tests. To perform them all,

must enter the command:

 python manage.py test

adding previously in the main file the following URL-card

lines:

<source lang="python"> urlpatterns + = patterns ('django.contrib.auth.views',

url (r '^ auth / password_reset /$',' password_reset'),

) </ Source>

Here we include one of the built-in views, designed to recover your password. This is necessary since

testing of the entire project is being accessed at the specified URL,

and if the view is not specified, the test will fail. By the way, you

also can try password_reset in (Fig. 2).

[[Image: LXF108 85 2.png | frame | center | Fig. 2. Forgot your password? This problem Django!]]

=== === Network Simulator

The number of tests has already reached six, but in addition to creating and

retrieve objects from the database, we need to test the response to

GET-and POST-requests. As you know, for these purposes there

special client: it emulates the query and returns the variables that are passed to the template for this URL. Add the

tests.py file after line 10 the following code:

<source lang="python" line="GESHI_NORMAL_LINE_NUMBERS" line start="11">

>>> From django.contrib.auth.models import User

>>> User = User.objects.create_user ('django_guru', 'user@example.com', 'password')

>>> User.save ()

>>> From django.test.client import Client

>>> C = Client ()

>>> C.login (username = 'django_guru', password = "password")

True

>>> Response = c.get ('/ news / 1 /')

>>> Response.status_code

200

>>> Print response.context [0] ['user']. Username

django_guru

>>> Response = c.post ('/ news / 1 /',{' username': "testuser", 'text':»»})

>>> Response.status_code

200

>>> Response = c.post ('/ news / 1 /',{' username': "testuser", 'text': »Comment text»})

>>> Response.status_code

302

>>> From news.models import Comment

>>> Comment = Comment.objects.get (news = news)

>>> Print comment.text

Comment text </ source>

See what is happening here. In lines 11-13 we create

New User (django_guru), and in 14-15 - the test client. In

line 16 django_guru authenticated, and now all of the system

will be performed by  in his name. On line 18 we went to our first news page, passing the client means GET-request.

To check that we have succeeded, we study the server response code

(Line 19) - it should be 200, or test will fail.

Then (lines 21-22), the reading of additional response data, we

verify that the request is made a registered user

django_guru. Now it's time to leave a comment - not in vain

We logged in? Line 23 is generated POST-request (second

argument to post () - dictionary data sent to the server).

Note that the value of the key text is blank, and

hence, the comment is not added, but the server still must return code 200 (line 25). But in line 26 we pass

all necessary data, and because after the comment we

redirected to the news page, the response code should be equal

302 (The requested URL moved). Lines 29-32 verify that

comment was actually added, we compare the text

with an initial value. Whew ... test passed.

Real Simple Syndication === ===

What is a news site without the tape? RSS and / or Atom feeds are everywhere - will be

and here, and Django us help you. Open the main file URL-cards and add to the end of the following lines:

<source lang="python" line="GESHI_NORMAL_LINE_NUMBERS">

from feeds import LatestNews

feeds = {

'Latest': LatestNews,

}

urlpatterns + = patterns ('',

(R '^ feeds / (? P <url> .*)/$',' django.contrib.syndication.views.feed ',

{'Feed_dict': feeds}),

)

</ Source>

Next you need to prepare a tape LatestNews, which we import at row 1. Create the root directory of the project feeds the file

__init__.py as follows:

<source lang="python" line="GESHI_NORMAL_LINE_NUMBERS">

# -*- Coding: utf-8 -*-

from django.contrib.syndication.feeds import Feed

from news.models import News

from django.contrib.syndication.feeds import FeedDoesNotExist

class LatestNews (Feed):

title = "Latest news from our site"

description = "Recent developments on the site mysite.com"

link = "http://127.0.0.1:8000/news/"

def items (self):

return News.objects.order_by ("-pub_date") [: 5]

def item_link (self, obj):

from django.core.urlresolvers import reverse

return 'http://127.0.0.1:8000% s'% reverse ('news.news_detail', kwargs = {"news_id": obj.pk})

</ Source>

[[Image: LXF108 86 1.png | thumb | 250px | Fig. 3. Firefox offers to subscribe to our news website updated - now hold on!]]

Fields title, description and link class LatestNews are required and are responsible for elements of the same name RSS. The method items ()

passes the required objects in the tape, and item_link () is responsible for the link

to the site. Now create a directory of feeds media / templates, and add

in it two files, latest_description.html and latest_title.html: they will

responsible for the news column form. In lates_description.html write:

 <nowiki> {{obj.description}} </ nowiki>

and latest_title.html:

 <nowiki> [{{obj.pub_date | date: "dmY"}}] {{obj.title}} </ nowiki>

Obj is a record of the sample, we

return in line 13, file feeds / __init__.py. Having at

http://127.0.0.1:8000/feeds/latest/, we shall offer Firefox

save feed. Members KDE, is likely to prefer

Akregator - with him, too, there is no problem (Fig. 3, 4)

=== === Understanding

To make life easier for web-developer, Django has included a large

number of representations to solve standard problems. For example, adding

in the main file URL-mapping the following code:

<source lang="python">

from django.views.generic.list_detail import object_list

from news.models import News

urlpatterns + = patterns ('',

('^ Lastnews / $', object_list, {

'Queryset': News.objects.all (). Order_by ('-pub_date') [: 10]

'Template_name': 'news / last_news.html',

'Template_object_name': 'last_news'})

) </ Source>

as well as replacing the file in news / templates / news / last_news.html

 {% For news in last_news%}

on

 {% For news in last_news_list%}

we will be able to view the latest news at

http://127.0.0.1:8000/lastnews/, causing no idea news.last_news. To make available both options must be found in presenting the line news.last_news

 "Last_news": news,

and replace it with

 "Last_news_list": news,

As you may have guessed, the general idea object_list designed to work with a list of objects. Still there is a submission for

O objects, depending on the date (django.views.generic.date_based .*), which makes it very easy to create backups of records:

* Archive_index - withdrawal of the last object added to the database;

* Archive_ {year, month, week, day, today} - the output of all the objects in a given year, month, week, day or today;

* Object_detail - the output of one object for a particular day.

General ideas are available for creating, updating and

deleting objects. They all work a little faster than by hand, but can solve only the most basic tasks. If the data in your application are selected from several

tables and is accompanied by the calculations, the overall presentation

will not help - then, they are common.

=== Add === variables on the fly

In the depths of the global context Django hide processors, the main task - to supply the template variables

and objects. Learn which ones are connected, you can in a tuple

TEMPLATE_CONTEXT_PROCESSORS in your settings.py. For example,

We are now working the following processors:

* Auth - information about the user: the object user, his rights of access and the messages that were sent to him;

* I18n - information about the current language of the site and the client;

* Request - information on request.

Besides them, there is a processor debug, sending in

pattern data of the executed SQL-queries, plus we can

write your own! To do this we create in the root of our

project directory and add the processors in it two files: __init__.py

and context_processors.py. The latter should contain the following code:

<source lang="python">

import settings

def site_settings (request):

return {'SETTINGS': settings} </ source>

To connect the processor, just list it in the tuple

TEMPLATE_CONTEXT_PROCESSORS. We check availability:

add a template news.html following:

 <nowiki> {{SETTINGS.TIME_ZONE}} </ nowiki>

Of course, TIME_ZONE can be replaced by any other variable that is defined in settings.py.

=== === Sam himself filter

With filters we met in [[LXF105: Django | LXF105]], but often there are situations when supplied with Django options are not enough. To write your own filter, create a radically

project directory templatetags / and add the files __init__.py

and filters.py. In filters.py write:

<source lang="python" line="GESHI_NORMAL_LINE_NUMBERS">

from django import template

register = template.Library ()

@ Register.filter

def exp (value, arg):

if value.isdigit () and arg.isdigit ():

return int (value) ** int (arg)

else:

return '<span style="color:red"> Error </ span>'

exp.is_safe = True </ source>

We have created a filter exp, which will have a value and an exponent and raises one another, if the arguments are not numbers, an error is generated. In line 5 we register

filter in the system with the help of a decorator. Line 11 indicates

that exp can return HTML-code. Because (for security), it automatically screened (<and> are replaced by &lt; and

> etc.), then, wanting to see pure HTML, we should prohibit

this behavior manually. The next step is loading of

library of filters to the template, which you need to add the

the following line:

 {% Load filters%}

In fact, Django looks for templates created by the library in the application root, so our filter still will not be available. It

not very convenient, especially if we want to use the

the same filter in many applications. The solution - to create a project

single library, and put in applications merely symbolic

references to it.

<source lang="bash"> ln-s / var / www / myproject / templatetags / / var / www / myproject / news / </ source>

Now test the filter by adding any template

line.

 <nowiki> {{"4" | exp: "4"}} </ nowiki>

At compile time, it will be replaced by 256. If we

write

 <nowiki> {{"a" | exp: "4"}} </ nowiki>

we see the word «Error», in red.

By the way, if we did not specify a filter in line 11 exp.is_safe = True, you could simply apply the filter directly into the safe

template:

 <nowiki> {{"a" | exp: "4" | safe}} </ nowiki>

After registering a filter in the system, information about it becomes available at http://127.0.0.1:8000/admin/doc/filters/

(Fig. 4)

[[Image: LXF108 87 1.png | frame | center | Fig. 4. The system politely tells you how to use the filter you created.]]

=== === The components of

If we have to perform any action before or after

as would be caused by representation, or if an error occurs, you can create your own components (middleware), or use

supplied with Django. We've already done this, when studied caching ([[LXF107: Django | LXF107]]). I recall that in the settings.py file is a tuple

MIDDLEWARE_CLASSES, which lists the components involved in the project. We are:

* Django.middleware.common.CommonMiddleware solve common problems: normalizes the URL (adds a www and the trailing /), prohibits access to the site specific robot interacts with Etag.

* Django.contrib.sessions.middleware.SessionMiddleware this session.

* Django.contrib.auth.middleware.AuthenticationMiddleware And this - authorization.

* Django.middleware.doc.XViewMiddleware used for automatic documentation Django.

* Django.middleware.locale.LocaleMiddleware Internationalization.

In addition to the above, the following are available in Django

components (django.middleware .*):

* Gzip.GZipMiddleware compression sends the page to save bandwidth.

* Http.ConditionalGetMiddleware Support for conditional GET-requests to work with the Last-Modified and Etag.

* Http.SetRemoteAddrFromForwardedFor reverse proxying.

* Cache.CacheMiddleware The same cache, which we encountered in the previous lesson.

* Transaction.TransactionMiddleware component for inclusion in SQL-queries of transaction structures: COMMIT, ROLLBACK.

Note that not all databases support transactions.

And finally, django.contrib.csrf.middleware.CsrfMiddleware, protecting against CSRF-attacks.

It has become a tradition, consider how to write your

own components. From a programmer's standpoint, it's just

Class Python, having a number of methods called Django at some point in time. The first is the constructor

__init__ (self), registering the components in the system. Next are the methods of determining the order of the code:

* Process_request () - runs after the request, but before Django will look for the requested address in the URL-maps;

* Process_view () - work out when the concrete representation is defined, but not yet started;

* Process_response () - runs after the presentation.

Used to compress the generated HTML.

process_exception () - called when something goes wrong or

were instituted an unhandled exception.

That is, in essence, that's all. But no - look at the sidebar and

away, away, away, read the documentation or the free

a book about Django - Django Book (http://www.djangobook.com); if you

prefer Russian, I advise you to look at http://cargo.caml.ru/djangobook. Finally, apply the acquired knowledge into practice - and let us know if you have something really worthwhile!

{{Box | center |

| Title =, etc., etc., other ...

| Table of Contents = Over four lessons, we had to consider almost all possible

Django, but something is left out ...

*, E-mail

Django offers a high-level API to send a message to

one action:

<source lang="python"> from django.core.mail import send_mail

send_mail ('Subject', 'message.', 'from@example.com', ['to@example.com'], fail_silently = False) </ source>

In addition, there is a function of mass communications, alerts, site administrators and managers, as well as working with

different content (HTML, text, graphics, etc.)

*; CSV and PDF

Django makes it easy to create data files, Comma Separated Values ​​(CSV), as well as PDF-documents using

Library ReportLab (http://www.reportlab.org/rl_toolkit.html).

*, Paged

When the number of objects is so large that one page is enough, have the support of a special class

Paginator, who helps organize paged:

<source lang="python">>>> from django.core.paginator import Paginator

>>> Objects = ['django', 'python', 'mysql', 'apache']

>>> P = Paginator (objects, 2)

>>> Page1 = p.page (1)

>>> Page1.object_list

['Django', 'python'] </ source>

Since most of our objects are stored in the database,

Django also offers class QuerySetPaginator, which takes no list, and many objects from the database.

*; Sitemaps

Want to have your site properly indexed by search

machines? You need to create his map! Django will help

here, and the function django.contrib.sitemaps.ping_google «cause»

Google to update the index for your website.

; * Managing multiple sites

One of the problems with which copes Django, is

control of several similar sites on the subject of a

installation. The project was originally designed as a platform for news portals, news, and one could appear

on multiple resources.

*; To help designers

Load the module templates to help designers:

 {% Load webdesign%}

you get at your disposal tag {% lorem%}, with

which you can display certain Latin phrase «lorem

ipsum ... »to fill the template" fish. "

; * And more

Django has a lot of other "goodies" that are very

well described in the accompanying documentation in English

language.

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