Forem: sevdimali

Custom Django Admin Actions

sevdimali — Thu, 19 Jan 2023 13:58:54 +0000

Django Admin Actions allows us to make bulk operations. The default one is the delete action.

Django allows us to create our custom actions.

For example, let’s think of a situation where we have a company model, and we regularly export data based on company types.

For this case, we will create our custom action and we will be able to export selected types of companies.

Let's start :)

As a first step, we will create our model and register it in admin.py:

models.py

from django.db import models

OPTIONS = (
    ('telco', 'Telecommunication'),
    ('log', 'Logistics'),
    ('agr', 'Agriculture'),
    ('aero', 'Aerospace'),
    ('pharm', 'Pharmaceutical'),
)


class Company(models.Model):
    name = models.CharField(max_length=255)
    company_type = models.CharField(max_length=15, choices=OPTIONS)
    founded = models.DateField(null=True, blank=True)
    status = models.BooleanField(default=True)

    def __str__(self):
        return self.name

    class Meta:
        verbose_name = 'Company'
        verbose_name_plural = 'Companies'

admin.py

from django.contrib import admin

from core.models import Company


class CompanyAdmin(admin.ModelAdmin):

    list_display = ['name', 'company_type', 'founded', 'status']

    list_filter = ['company_type']


admin.site.register(Company, CompanyAdmin)

Now let's add some data to our database:

Now we will modify our admin.py as below:

from django.contrib import admin
from django.http import HttpResponseRedirect

from core.models import Company


class CompanyAdmin(admin.ModelAdmin):

    @admin.action(description='Export')
    def export_objects(self, request, queryset):
        selected = queryset.values_list('pk', flat=True)
        return HttpResponseRedirect('/export/?ids=%s' % (
            ','.join(str(pk) for pk in selected),
        ))

    list_display = ['name', 'company_type', 'founded', 'status']

    actions = [export_objects]

    list_filter = ['company_type']


admin.site.register(Company, CompanyAdmin)

In the above code, we created our action function(export_objects), here we get selected object’s ids from the queryset and passed them as a get parameter to our export URL.

Also in our CompanyAdmin class, we added a new action to actions.

actions = [export_objects]

So in this step, we have to create our export view and URL.

urls.py
from django.contrib import admin
from django.urls import path
from core.views import export

urlpatterns = [
path('admin/', admin.site.urls),
path('export/', export, name='export'),
]
views.py

from django.core import serializers
from django.http import HttpResponse
from core.models import Company


def export(request):
    ids = request.GET.get('ids').split(',')
    qs = Company.objects.filter(id__in = ids)
    response = HttpResponse(content_type="application/json")
    serializers.serialize("json", qs, stream=response)
    return response

The final result is like below:

The complete source code is available here.

Thanks for reading. I hope you enjoyed it ❤.
The post first appeared in my blog
Keep Learning..!

How to create thumbnails programmatically in Django

sevdimali — Mon, 16 Jan 2023 16:28:02 +0000

Django-imagekit is an app for processing images. You can programmatically change images with imagekit. For this blog post, we will create thumbnails and look for its Django Rest Framework usage (DRF).

1. Installation of django-imagekit

pip install pillow
pip install django-imagekit
INSTALLED_APPS = [
'imagekit',
]

2. Creating a thumbnail with django-imagekit
For creating a thumbnail in Django from an image we will use ImageSpecField. An image spec is a type of image generator that generates a new image from a source image. Now let’s look for a specific example.

Models.py

class Category(models.Model):
    name = models.CharField(
        verbose_name=_("Category Name"),
        help_text=_("Required and unique"),
        max_length=255,
        unique=True,
    )
    picture = models.ImageField(null=True, upload_to="images/", blank=True, verbose_name="Category picture")
    thumbnail150x150 = ImageSpecField(source='picture', processors=[ResizeToFill(150, 150)], format="PNG",
                                      options={'quality': 60})
    cdate = models.DateTimeField(auto_now_add=True)
    udate = models.DateTimeField(auto_now=True)

In the above example, we specified source=’picture’, in this way we tell use the picture field as a source and generate a new image.

So in your templates, you can simply use it like below:

<img src="{{ category.thumbnail150x150.url }}" alt="img">

If you want to not create a new image, just change the original image, then we will use ProcessedImageField and replace a source to upload_to.

class Category(models.Model):
    name = models.CharField(
        verbose_name=_("Category Name"),
        help_text=_("Required and unique"),
        max_length=255,
        unique=True,
    )
    thumbnail150x150 = ProcessedImageField(upload_to="images/", processors=[ResizeToFill(150, 150)], format="PNG",
                                      options={'quality': 60})
    cdate = models.DateTimeField(auto_now_add=True)
    udate = models.DateTimeField(auto_now=True)

You are able to use as many processors as you’d like, which will all be run in order.

class Category(models.Model):
    name = models.CharField(
        verbose_name=_("Category Name"),
        help_text=_("Required and unique"),
        max_length=255,
        unique=True,
    )
    picture = models.ImageField(null=True, upload_to="images/", blank=True, verbose_name="Category picture")
    thumbnail150x150 = ImageSpecField(source='picture', processors=[ResizeToFill(150, 150), TrimBorderColor(), ],
                                      format="PNG",
                                      options={'quality': 60})
    cdate = models.DateTimeField(auto_now_add=True)
    udate = models.DateTimeField(auto_now=True)

3. “django-imagekit” usage with DRF(Django Rest Framework)

class CategorySerializer(serializers.ModelSerializer):
    picture = serializers.SerializerMethodField()
    thumbnail = serializers.SerializerMethodField()
    class Meta:
        model = Category
        fields = ('id', 'name', 'picture','thumbnail')
    def get_picture(self, obj):
        return obj.picture.url
    def get_thumbnail(self, obj):
        return obj.thumbnail150x150.url

Thanks for reading. I hope you enjoyed it ❤.
The post first appeared in my blog
Keep Learning..!

How to use UUID in Django

sevdimali — Sat, 03 Dec 2022 11:27:30 +0000

UUID(Universal Unique Identifier) is a Python library that generates random objects of 128 bits. It is a standard built-in Python library which means you don’t need to install anything. There are three main algorithms used for generating randoms:

Using IEEE 802 MAC addresses as a source of uniqueness
Using pseudo-random numbers
Using well-known strings combined with cryptographic hashing
The UUID uses getnode() to retrieve the MAC value on a given system:

import uuid
print(uuid.getnode())
251053329979042

First, let’s look at how we can use UUID in general:

import uuidp
print(uuid.uuid4())
cae6f5a3-377d-4eaa-8d27-3ff12aece93e

UUID usage in Django
Now, let’s look at using UUID usage in Django.

It is commonly used to replace the Django id field. By default, Django gives each model auto-incrementing primary key field:

id = models.AutoField(primary_key=True)

if you want to explicitly set the primary key you must specify primary_key=True then Django won’t add this field automatically because it detects that you set it manually.

Now let’s look real example. Assume that you have a Subscription Model

class Subscription (models.Model):
name = models.CharField(verbose_name=_("Subcription Name"),
                        help_text=_("Required and unique"),
                        max_length=255,
                        unique=True,
)
cdate = models.DateTimeField(auto_now_add=True)
udate = models.DateTimeField(auto_now=True)

In general when we access this model’s detail like below:

https://domain.com/subcriptions/1

In the frontend, users can access other’s data by replacing 1 to 2,3,4, etc. We can call it a simple Security leak. For in these cases we can replace the id field with UUID.

class Subscription (models.Model):
id = models.UUIDField(primary_key=True,
                      default=uuid.uuid4,
                      editable=False)
                      name = models.CharField(
                      verbose_name=_("Subcription Name"),
                      help_text=_("Required and unique"),
                      max_length=255,
                      unique=True,
                      )
cdate = models.DateTimeField(auto_now_add=True)
udate = models.DateTimeField(auto_now=True)

As we showed above UUID generates random and it is not predictable.

Thanks for reading. I hope you enjoyed it ❤.
The post first appeared in my blog
Keep Learning..!

Creating thumbnails programmatically in Django using django-imagekit

sevdimali — Tue, 29 Nov 2022 16:35:06 +0000

Installation of django-imagekit

pip install pillow
pip install django-imagekit
INSTALLED_APPS = [
'imagekit',
]

Creating a thumbnail with django-imagekit
For creating a thumbnail in Django from an image we will use ImageSpecField. An image spec is a type of image generator that generates a new image from a source image. Now let’s look for a specific example.

Models.py

class Category(models.Model):
    name = models.CharField(
        verbose_name=_("Category Name"),
        help_text=_("Required and unique"),
        max_length=255,
        unique=True,
    )
    picture = models.ImageField(null=True, upload_to="images/", blank=True, verbose_name="Category picture")
    thumbnail150x150 = ImageSpecField(source='picture', processors=[ResizeToFill(150, 150)], format="PNG",
                                      options={'quality': 60})
    cdate = models.DateTimeField(auto_now_add=True)
    udate = models.DateTimeField(auto_now=True)

In the above example, we specified source=’picture’, in this way we tell use the picture field as a source and generate a new image.

So in your templates, you can simply use it like below:

<img src="{{ category.thumbnail150x150.url }}" alt="img">

If you want to not create a new image, just change the original image, then we will use ProcessedImageField and replace a source to upload_to.

class Category(models.Model):
    name = models.CharField(
        verbose_name=_("Category Name"),
        help_text=_("Required and unique"),
        max_length=255,
        unique=True,
    )
    thumbnail150x150 = ProcessedImageField(upload_to="images/", processors=[ResizeToFill(150, 150)], format="PNG",
                                      options={'quality': 60})
    cdate = models.DateTimeField(auto_now_add=True)
    udate = models.DateTimeField(auto_now=True)

You are able to use as many processors as you’d like, which will all be run in order.

class Category(models.Model):
    name = models.CharField(
        verbose_name=_("Category Name"),
        help_text=_("Required and unique"),
        max_length=255,
        unique=True,
    )
    picture = models.ImageField(null=True, upload_to="images/", blank=True, verbose_name="Category picture")
    thumbnail150x150 = ImageSpecField(source='picture', processors=[ResizeToFill(150, 150), TrimBorderColor(), ],
                                      format="PNG",
                                      options={'quality': 60})
    cdate = models.DateTimeField(auto_now_add=True)
    udate = models.DateTimeField(auto_now=True)

“django-imagekit” usage with DRF(Django Rest Framework)

class CategorySerializer(serializers.ModelSerializer):
    picture = serializers.SerializerMethodField()
    thumbnail = serializers.SerializerMethodField()
    class Meta:
        model = Category
        fields = ('id', 'name', 'picture','thumbnail')
    def get_picture(self, obj):
        return obj.picture.url
    def get_thumbnail(self, obj):
        return obj.thumbnail150x150.url

Thanks for reading. I hope you enjoyed it ❤.
The post first appeared in my blog

Keep Learning..!