Django CRUD (создание, получение, обновление, удаление) Представления на основе функций

Опубликовано: 24 Февраля, 2022

Django - это веб-фреймворк на основе Python, который позволяет быстро создавать веб-приложения без всех проблем с установкой или зависимостями, которые обычно возникают с другими фреймворками. Django основан на архитектуре MVT (шаблон представления модели) и вращается вокруг операций CRUD (создание, получение, обновление, удаление). CRUD лучше всего можно объяснить как подход к созданию веб-приложения Django. В общем случае CRUD означает выполнение операций Create, Retrieve, Update и Delete над таблицей в базе данных. Давайте обсудим, что на самом деле означает CRUD,

Создать - создать или добавить новые записи в таблицу в базе данных.
Получить - читать, извлекать, искать или просматривать существующие записи в виде списка (представление списка) или извлекать конкретную запись в деталях (подробное представление)
Обновить - обновить или отредактировать существующие записи в таблице в базе данных.
Удалить - удалить, деактивировать или удалить существующие записи в таблице в базе данных.

Django CRUD (создание, получение, обновление, удаление) представлений на основе функций

Illustration of How to create and use CRUD view using an Example. Consider a project named geeksforgeeks having an app named geeks.

Refer to the following articles to check how to create a project and an app in Django.
How to Create a Basic Project using MVT in Django?
How to Create an App in Django ?

After you have a project and an app, let’s create a model of which we will be creating instances through our view. In geeks/models.py,

# import the standard Django Model
# from built-in library
from django.db import models
   
# declare a new model with a name "GeeksModel"
class GeeksModel(models.Model):
  
    # fields of the model
    title = models.CharField(max_length = 200)
    description = models.TextField()
  
    # renames the instances of the model
    # with their title name
    def __str__(self):
        return self.title

After creating this model, we need to run two commands in order to create Database for the same.

Python manage.py makemigrations
Python manage.py migrate

Now we will create a Django ModelForm for this model. Refer this article for more on modelform – Django ModelForm – Create form from Models. create a file forms.py in geeks folder,

from django import forms
from .models import GeeksModel
  
  
# creating a form
class GeeksForm(forms.ModelForm):
  
    # create meta class
    class Meta:
        # specify model to be used
        model = GeeksModel
  
        # specify fields to be used
        fields = [
            "title",
            "description",
        ]

Create View

Create View refers to a view (logic) to create an instance of a table in the database. It is just like taking an input from a user and storing it in a specified table.
In geeks/views.py,

from django.shortcuts import render
  
# relative import of forms
from .models import GeeksModel
from .forms import GeeksForm
  
  
def create_view(request):
    # dictionary for initial data with 
    # field names as keys
    context ={}
  
    # add the dictionary during initialization
    form = GeeksForm(request.POST or None)
    if form.is_valid():
        form.save()
          
    context["form"]= form
    return render(request, "create_view.html", context)

Create a template in templates/create_view.html,

<form method="POST" enctype="multipart/form-data">
  
    <!-- Security token -->
    {% csrf_token %}
  
    <!-- Using the formset -->
    {{ form.as_p }}
      
    <input type="submit" value="Submit">
</form>

Now visit http://localhost:8000/

To check complete implementation of Function based Create View, visit Create View – Function based Views Django.

Retrieve View

Retrieve view is basically divided into two types of views Detail View and List View.

List View

List View refers to a view (logic) to list all or particular instances of a table from the database in a particular order. It is used to display multiple types of data on a single page or view, for example, products on an eCommerce page.
In geeks/views.py,

from django.shortcuts import render
  
# relative import of forms
from .models import GeeksModel
  
  
def list_view(request):
    # dictionary for initial data with 
    # field names as keys
    context ={}
  
    # add the dictionary during initialization
    context["dataset"] = GeeksModel.objects.all()
          
    return render(request, "list_view.html", context)

Create a template in templates/list_view.html,

<div class="main">
  
    {% for data in dataset %}.
  
    {{ data.title }}<br/>
    {{ data.description }}<br/>
    <hr/>
  
    {% endfor %}
  
</div>

Now visit http://localhost:8000/

To check complete implementation of Function based List View, visit List View – Function based Views Django

Detail View

Detail View refers to a view (logic) to display a particular instnace of a table from the database with all the necessary details. It is used to display multiple types of data on a single page or view, for example, profile of a user.
In geeks/views.py,

from django.urls import path
  
# importing views from views..py
from .views import detail_view
  
urlpatterns = [
    path("<id>", detail_view ),
]

Let’s create a view and template for the same. In geeks/views.py,

from django.shortcuts import render
  
# relative import of forms
from .models import GeeksModel
  
# pass id attribute from urls
def detail_view(request, id):
    # dictionary for initial data with 
    # field names as keys
    context ={}
  
    # add the dictionary during initialization
    context["data"] = GeeksModel.objects.get(id = id)
          
    return render(request, "detail_view.html", context)

Create a template in templates/Detail_view.html,

<div class="main">
      
    <!-- Specify fields to be displayed -->
    {{ data.title }}<br/>
    {{ data.description }}<br/>
  
</div>

Let’s check what is there on http://localhost:8000/1

To check complete implementation of Function based Detail View, visit Detail View – Function based Views Django

Update View

Update View refers to a view (logic) to update a particular instance of a table from the database with some extra details. It is used to update enteries in the database for example, updating an article at geeksforgeeks.
In geeks/views.py,

from django.shortcuts import (get_object_or_404,
                              render,
                              HttpResponseRedirect)
  
# relative import of forms
from .models import GeeksModel
from .forms import GeeksForm
  
# after updating it will redirect to detail_View
def detail_view(request, id):
    # dictionary for initial data with 
    # field names as keys
    context ={}
   
    # add the dictionary during initialization
    context["data"] = GeeksModel.objects.get(id = id)
           
    return render(request, "detail_view.html", context)
  
# update view for details
def update_view(request, id):
    # dictionary for initial data with 
    # field names as keys
    context ={}
  
    # fetch the object related to passed id
    obj = get_object_or_404(GeeksModel, id = id)
  
    # pass the object as instance in form
    form = GeeksForm(request.POST or None, instance = obj)
  
    # save the data from the form and
    # redirect to detail_view
    if form.is_valid():
        form.save()
        return HttpResponseRedirect("/"+id)
  
    # add form dictionary to context
    context["form"] = form
  
    return render(request, "update_view.html", context)

Now create following templates in templates folder,
In geeks/templates/update_view.html,

<div class="main">
    <!-- Create a Form -->
    <form method="POST">
        <!-- Security token by Django -->
        {% csrf_token %}
  
        <!-- form as paragraph -->
        {{ form.as_p }}
  
        <input type="submit" value="Update">
    </form>
  
</div>

In geeks/templates/detail_view.html,

<div class="main">
    <!-- Display attributes of instance -->
    {{ data.title }} <br/>
    {{ data.description }}
</div>

Let’s check if everything is working, visithttp://localhost:8000/1/update.

To check complete implementation of Function based update View, visit Update View – Function based Views Django

Delete View

Delete View refers to a view (logic) to delete a particular instance of a table from the database. It is used to delete entries in the database for example, deleting an article at geeksforgeeks.
In geeks/views.py

from django.shortcuts import (get_object_or_404,
                              render, 
                              HttpResponseRedirect)
  
from .models import GeeksModel
  
  
# delete view for details
def delete_view(request, id):
    # dictionary for initial data with 
    # field names as keys
    context ={}
  
    # fetch the object related to passed id
    obj = get_object_or_404(GeeksModel, id = id)
  
  
    if request.method =="POST":
        # delete object
        obj.delete()
        # after deleting redirect to 
        # home page
        return HttpResponseRedirect("/")
  
    return render(request, "delete_view.html", context)

Now a url mapping to this view with a regular expression of id,
In geeks/urls.py

from django.urls import path
  
# importing views from views..py
from .views import delete_view
urlpatterns = [
    path("<id>/delete", delete_view ),
]

Template for delete view includes a simple form confirming whether user wants to delete the instance or not. In geeks/templates/delete_view.html,

<div class="main">
    <!-- Create a Form -->
    <form method="POST">
        <!-- Security token by Django -->
        {% csrf_token %}
        Are you want to delete this item ?
        <input type="submit" value="Yes" />
        <a href="/">Cancel </a>
    </form>
</div>

Everything ready, now let’s check if it is working or not, visit http://localhost:8000/2/delete

To check complete implementation of Function based Delete View, visit Delete View – Function based Views Django

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