ORM -- database addition, deletion, modification and query operation logic

1. Data acquisition logic

        1.1 Get multiple pieces of data

        1.2 Get a single piece of data

 2. Create data logic

 3. Modify the data logic

        3.1 Data before modification

         3.2 modify

        3.3 After modification

  

4. Delete data logic

        When deleting data from a table , From the table model, if you define foreign keys on_delete=models.CASCADE attribute , Then from the association in the table

                 Data will also be deleted .

The above example code ：

        # /projects/views.py

import json

from django.http import HttpResponse, JsonResponse
# Create your views here.

#  Subapplication view 
from django.views import View
from projects import models


class ProjectsView(View):
    """
     Class view 
    :param View:  Inherited from from django.views import View
    :return: HttpResponse object 
    """

    def get(self, request):
        #  Query all project information 
        # GET /projects/
        projects_list = []
        qs = models.Projects.objects.all()
        for item in qs:
            projects_list.append(
                {
                    'id': item.id,
                    'name': item.full_name,
                    'leader': item.leader,
                    'create_time': item.create_time,
                    'update_time': item.update_time,
                }
            )
        return JsonResponse(projects_list, safe=False)

    def post(self, request):
        #  New projects 
        # POST /projects/  json Format parameters 
        python_data = json.loads(request.body)
        pro_obj = models.Projects.objects.create(full_name=python_data['name'], leader=python_data['leader'],
                                                 is_execute=python_data['is_execute'], desc=python_data['desc'])
        result = {
            'full_name': pro_obj.full_name,
            'leader': pro_obj.leader,
            'desc': pro_obj.desc,
            'msg': ' Create success '
        }
        return JsonResponse(result, safe=False, status=203)


class ProjectDetailView(View):

    def get(self, request, pk):
        #  Query the specified item 
        # GET /projects/<int:pk>/
        pro_obj = models.Projects.objects.get(id=pk)
        result = {
            'id': pro_obj.id,
            'name': pro_obj.full_name,
            'leader': pro_obj.leader,
            'create_time': pro_obj.create_time,
            'update_time': pro_obj.update_time,
        }
        return JsonResponse(result, status=203)

    def put(self, request, pk):
        #  Modification item 
        # PUT /projects/<int:pk>/ json Format parameters 
        python_data = json.loads(request.body)
        count = models.Projects.objects.filter(id=pk).update(full_name=python_data['name'],
                                                               leader=python_data['leader'])
        result = {
            'data': python_data,
            'msg': ' The update is successful ',
            'count': count,
        }
        return JsonResponse(result, status=203)

    def delete(self, request, pk):
        #  Delete the project 
        # DELETE /projects/<int:pk>
        status = models.Projects.objects.filter(id=pk).delete()
        result = {
            'msg': f' Delete {pk} success ',
            'count': status,
        }
        return JsonResponse(result, safe=False, status=203)