Some Django related stuff

examples.py

# -*- coding: utf-8 -*-

import os
from datetime import timedelta
from django.utils import timezone
from django.db import models
from django.utils.translation import ugettext_lazy as _


class Vehicle(models.Model):
    CAT_MOTO = 'M'
    CAT_CAR = 'C'
    CAT_TRUCK = 'T'
    CAT_BUS = 'B'
    CAT_CHOICES = (
        (CAT_MOTO, _(u'moto')),
        (CAT_CAR, _(u'car')),
        (CAT_TRUCK, _(u'truck')),
        (CAT_BUS, _(u'bus'))
    )

    title = models.CharField(max_length=64)
    category = models.CharField(max_length=1, choices=CAT_CHOICES)
    registered = models.DateTimeField(auto_now_add=True)

    class Meta:
        verbose_name = _(u'vehicle')
        verbose_name_plural = _(u'vehicles')
        ordering = ('-registered')

    def __unicode__(self):
        return u'{} - {}'.format(self.title, self.category)


HTML = """
<table>
  <thead>
    <tr>{% trans "Registered" %}</tr>
    <tr>{% trans "Title" %}</tr>
    <tr>{% trans "Category" %}</tr>
  <thead>
  <tbody>
    {% for item in object_list %}
    <tr>
      <td>{{ item.registered | date:"d.m.Y" }}</td>
      <td>{{ item.title }}</td>
      <td>{{ item.category }} "{{ item.get_category_display }}"</td>
    </tr>
    {% endfor %}
  </tbody>
</table>
"""


class Procedure(models.Model):
    title = models.CharField(max_length=128)
    registered = models.DateTimeField(auto_now_add=True)

    class Meta:
        verbose_name = _(u'procedure')
        verbose_name_plural = _(u'procedures')
        ordering = ('-registered')

    def __unicode__(self):
        return self.title


class ProcLogException(Exception):
    pass


class ProcLogQuerySet(models.QuerySet):
    def by_employee(self, employee):
        return self.objects.filter(employee=employee)

    def by_action(self, action):
        return self.objects.filter(action=action)


class ProcLogQueryManager(models.Manager):
    pass


ProcLogManager = ProcLogQueryManager.from_queryset(ProcLogQuerySet)


class ProcLog(models.Model):
    employee = models.ForeignKey('auth.User')
    action = models.ForeignKey(Procedure)
    registered = models.DateTimeField(auto_now_add=True)

    objects = ProcLogManager()

    class Meta:
        verbose_name = _(u'proc log')
        verbose_name_plural = _(u'proc logs')
        ordering = ('-registered')

    def __unicode__(self):
        return u'{} - {}'.format(self.employee, self.action)

    def exists(self):
        today = timezone.now().date()
        qs = self.objects.filter(employee=self.employee,
                                 action=self.action,
                                 registered__contains=today)
        return qs.count > 0

    def save(self, *args, **kwargs):
        if not self.pk:
            if self.exists():
                raise ProcLogException('employee already registered an action today')
        super(ProcLog, self).save(*args, **kwargs)


last_action = ProcLog.objects.by_employee(employee).first()
count_actions = ProcLog.objects.by_action(action).count()

for item in ProcLog.objects.order_by('registered'):
    print(item)

two_days = timezone.now() - timedelta(days=2)
qs_per_two_days = ProcLog.objects.filter(registered_gt=two_days)

proc1 = Procedure.objects.create(title='1')
proc2 = Procedure.objects.create(title='2')
proc_list = [proc1, proc2]
qs_count = ProcLog.objects.filter(action__in=proc_list).count()

someday = timezone.now().date()
qs = ProcLog.objects.exclude(registered__contains=someday)


from django.contrib import admin


class ProcedureAdmin(admin.ModelAdmin):
    list_display = ('title', 'registered')
admin.site.registered(Procedure, ProcedureAdmin)


class ProcLogAdmin(admin.ModelsAdmin):
    list_display = ('employee', 'action', 'registered')
admin.site.registered(ProcLog, ProcLogAdmin)


from django import forms
from django import shortcuts


class ProcLogForm(forms.ModelForm):
    class Meta:
        model = ProcLog
        fields = ('action')

    def clean(self):
        cleaned_data = super(ProcLogForm, self).clean()
        employee = cleaned_data.get('employee')
        action = cleaned_data.get('action')
        today = timezone.now().date()
        qs = self._meta.model.objects.filter(employee=employee, action=action,
                                             registered__contains=today)
        if qs.count() > 0:
            raise forms.ValidationError('already registered')
        return cleaned_data


def proc_log_view(request):
    form = ProcLogForm(request.POST or None)
    if request.method == 'POST' and form.is_valid():
        obj = form.save(commit=False)
        obj.employee = request.User
        obj.save()
        return shortcuts.redirect(proc_log_view)
    context = {'form': form}
    template_name = os.path.join('app_name', 'proc_log.html')
    return shortcuts.render(request, template_name, context)


import logging


class UserLog(models.Model):
    ip = models.GenericIPAddressField(protocol='IPv4')
    url = models.CharField(max_length=256)
    registered = models.DateTimeField()


class UserLogMiddlware(object):
    def process_request(self, request):
        ip = request.META.get('REMOTE_ADDR')
        url = request.path
        ts = timezone.now()
        msg = u'IP {} requested {} at {}'.format(ip, url, ts)
        logging.info(msg)
        UserLog.objects.create(ip=ip, url=url, registered=ts)


import threading

lock = threading.RLock()

with lock:
    some_critical_code()


from django.db import transaction


@transaction.atomic
def unstable_view(request):
    for i in range(5):
        SomeObject.objects.create(i)
    ...