Wherever you are, be there!: Django

Showing posts with label Django. Show all posts

2014-08-19

Showing the description of a choice in a Django template

Sometimes you would like to show the description of a choice instead of its code in a Django template. One way to achieve that is to define a property in the model and referencing it in a template as below:

{{ object.status_desc }}

=== models.py ===

from django.db.models import IntegerField, CharField, Model

class Invoice(Model):

    STATUS_TYPE = (
        ('A', 'Active'),
        ('I', 'Inactive'),
    )

    invoice_no = IntegerField()
    status = CharField(max_length=1, choices=STATUS_TYPE, default='A')

    @property
    def status_desc(self):
        return dict(self.STATUS_TYPE)[self.status]

EDITED 2015-07-13 Turn out there is a django function for this purpose: Model.get_FOO_display()

2014-08-16

Django File Upload

The following is a minimalistic but complete example of handling file upload in Django 1.6.

=== forms.py ===

from django import forms

class UploadFileForm(forms.Form):
    file = forms.FileField()

=== views.py ===

import os.path
from django.http import HttpResponse
from django.shortcuts import render
from .forms import UploadFileForm
          
def home(request):
    if request.method == 'POST':
        form = UploadFileForm(request.POST, request.FILES)
        if form.is_valid():
            handle_uploaded_file(request.FILES['file'])
            return HttpResponse("Upload Successful.")
    else:
        form = UploadFileForm()
    return render(request, 'home.html', {'form': form})

def handle_uploaded_file(f):
    with open(os.path.join('/path/to/', f.name), 'wb+') as destination:
        for chunk in f.chunks():
            destination.write(chunk)

=== home.html ===
<html>
<body>

<form action="" method="post" {% if form.is_multipart %}enctype="multipart/form-data"{% endif %}>
  {{ form.as_p }}
  {% csrf_token %}
  <input type="submit" value="Submit" />
</form>

</body>
</html>

2014-06-09

How is_authenticated() is done in Django?

I tried to understand how is_authenticated() is done in Django, so I did a code search in Django's GitHub repository and found two definitions of it in django/contrib/auth/models.py as shown below:

I am surprised that one definition always return true, while the other always return false, as I was expecting some sort of logic to check if a user is logged or not.

Turn out it is simpler than that. The is_authenticated() method is bound to either a User object or an AnonymousUser object. So at the time is_authenticated() is called, it already knows whether the user is authenticated or not by the type of the object.

Neat.

2013-12-08

Django 1.6 source file count and directory structure

2013-08-28

Django logging setting

It took me some time to figure out how to set up logging in Django. What I want to do is to log to a pair of rotating files each 1MB in size.

What I come up with is the following code segment to replace the LOGGING setting in the settings.py:

U_LOGFILE_NAME = r'/path/to/log.txt'
U_LOGFILE_SIZE = 1 * 1024 * 1024
U_LOGFILE_COUNT = 2
U_LOGFILE_APP1 = 'app1'
U_LOGFILE_APP2 = 'app2'

LOGGING = {
'version': 1,
'disable_existing_loggers': False,
'formatters': {
'standard': {
'format' : "[%(asctime)s] %(levelname)s [%(name)s:%(lineno)s] %(message)s",
#'datefmt' : "%d/%b/%Y %H:%M:%S"
},
},
'filters': {
'require_debug_false': {
'()': 'django.utils.log.RequireDebugFalse'
}
},
'handlers': {
'mail_admins': {
'level': 'ERROR',
'filters': ['require_debug_false'],
'class': 'django.utils.log.AdminEmailHandler'
},
'logfile': {
'level':'DEBUG',
'class':'logging.handlers.RotatingFileHandler',
'filename': U_LOGFILE_NAME,
'maxBytes': U_LOGFILE_SIZE,
'backupCount': U_LOGFILE_COUNT,
'formatter': 'standard',
},
},
'loggers': {
'django.request': {
'handlers': ['mail_admins'],
'level': 'ERROR',
'propagate': True,
},
U_LOGFILE_APP1: {
'handlers': ['logfile'],
'level': 'DEBUG',
'propagate': True,
},
U_LOGFILE_APP2: {
'handlers': ['logfile'],
'level': 'DEBUG',
'propagate': True,
},
}
}

Usage:

import os
log = logging.getLogger(__name__)

log.debug("debug")

log.info("info")

log.warn("warn")

log.error("error")

This post also appears in Django Snippets.

2013-05-14

Set up Django 1.5.1 in DreamHost VPS

This post is about setting up Django 1.5.1 in a virtualenv in DreamHost VPS with Apache2 and mod_wsgi 3.4, and is mostly an update to the following post about three years ago:

http://www.wombatnation.com/2010/06/django-on-dreamhost-ps/comment-page-1

Software Versions:

Apache 2.2.22

Django 1.5.1

mod_wsgi 3.4

PIP 1.3.1

Python 2.6.6

VirtualEnv 1.9.1

1. Sign up a VPS account with DreamHost.

2. Create a regular user [user] in the VPS. The Django project will run under this account.

3. Create an admin user [admin] in the VPS to manage the web server. This admin account has sudo privileges.

4. Install Python PIP (1.3.1)

[admin]$ sudo easy_install pip

PIP is installed at /usr/local/bin/pip.

5. Upgrade VirtualEnv (from 1.4.9 to 1.9.1)

[admin]$ sudo pip install --upgrade virtualenv

6. Create a virtualenv and install Django (1.5.1) in it

[user]$ mkdir ~/django

[user]$ virtualenv ~/django/env

[user]$ source ~/django/env/bin/activate

[env]$ pip install django

7. Create a Django project (demo)

[env]$ cd ~/django

[env]$ django-admin.py startproject demo

8. Verify Django project is working

[env]$ cd ~/django/demo

[env]$ python manage.py runserver 0.0.0.0:8000

Visit http://your.domain.com:8000 to verify Django project is up and running.

9. Install mod_wsgi 3.4

[admin]$ mkdir ~/src

[admin]$ cd ~/src

[admin]$ wget http://modwsgi.google.com/files/mod_wsgi-3.4.tar.gz

[admin]$ tar xzvf mod_wsgi-3.4.tar.gz

[admin]$ cd mod_wsgi-3.4

[admin]$ ./configure --with-apxs=/usr/local/dh/apache2/template/sbin/apxs --with-python=/usr/bin/python

[admin]$ make

[admin]$ sudo make install

mod_wsgi is installed at /usr/local/dh/apach2/template/lib/modules/mod_wsi.so

10. Edit httpd.conf

[admin]$ sudo vim /usr/local/dh/apache2/apache2-psNNNNNN/etc/httpd.conf

psNNNNNN is your VPS id.

add the following line in the LoadModule section:

LoadModule wsgi_module /dh/apache2/template/lib/modules/mod_wsgi.so

add the following line outside of VirtualHost directive:

WSGIPythonPath /home/user/django/env/lib/python2.6/site-packages

add following line inside the VirtualHost directive:

   WSGIScriptAlias /demo /home/user/django/demo/demo/wsgi.py

11. Restart Apache

   [admin]$ sudo /etc/init.d/httpd2 restart apache2-psNNNNNN

12. Edit wsgi.py

   [env]$ vim ~/django/demo/demo/wsgi.py

   add next two lines at the top of the file:

   import sys

   sys.path.insert(0, '/home/user/django/demo')

13. Create a Django app (demoapp) and update urls.py

   [env]$ cd ~/django/demo

   [env]$ python manage.py startapp demoapp

   [env]$ vim ~/django/demo/demoapp/views.py

   Make it look like:

from django.http import HttpResponse

def index(request):

return HttpResponse("Hello world!")

[env]$ vim ~/django/demo/demo/urls.py

Add a url pattern:

url(r'^$', 'demoapp.views.index')

14. Verify

Visit http://your.domain.com/demo, will see "Hello World!" in browser.

-End-

Wherever you are, be there!