ORM--数据库增删改查操作逻辑

1.数据获取逻辑

        1.1 获取多条数据

        1.2 获取单条数据

 2.创建数据逻辑

 3.修改数据逻辑

        3.1 修改前的数据

         3.2 修改

        3.3 修改后

4.删除数据逻辑

        删除表中数据时，从表模型若定义外键on_delete=models.CASCADE属性，则从表中的关联

                数据也会被删除。

以上示例代码：

        # /projects/views.py

import json

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

# 子应用视图
from django.views import View
from projects import models


class ProjectsView(View):
    """
    类视图
    :param View: 继承自from django.views import View
    :return: HttpResponse对象
    """

    def get(self, request):
        # 查询所有项目信息
        # 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):
        # 新建项目
        # POST /projects/  json格式参数
        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': '创建成功'
        }
        return JsonResponse(result, safe=False, status=203)


class ProjectDetailView(View):

    def get(self, request, pk):
        # 查询指定项目
        # GET /projects//
        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):
        # 修改项目
        # PUT /projects// json格式参数
        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': '更新成功',
            'count': count,
        }
        return JsonResponse(result, status=203)

    def delete(self, request, pk):
        # 删除项目
        # DELETE /projects/
        status = models.Projects.objects.filter(id=pk).delete()
        result = {
            'msg': f'删除{pk}成功',
            'count': status,
        }
        return JsonResponse(result, safe=False, status=203)