帮我用Django2.2写一个任务管理系统

创建一个任务管理系统，我们可以使用Django框架的模型、视图和模板来构建基本功能。以下是简化的步骤和关键代码示例，假设我们将任务分为待办任务和已完成任务两个状态。

1. **安装Django和相关库**:

   pip install django

2. **设置项目和应用**:
创建一个新的Django项目和名为'task_manager'的应用：

   django-admin startproject task_manager
   cd task_manager
   python manage.py startapp tasks

3. **models.py (tasks应用)**:

   from django.db import models
   from django.contrib.auth.models import User

   class Task(models.Model):
       title = models.CharField(max_length=100)
       description = models.TextField()
       status = models.CharField(choices=[('todo', '待办'), ('done', '完成')], default='todo')
       assigned_to = models.ForeignKey(User, on_delete=models.CASCADE)
       created_at = models.DateTimeField(auto_now_add=True)
       updated_at = models.DateTimeField(auto_now=True)

   class TaskHistory(models.Model):
       task = models.ForeignKey(Task, on_delete=models.CASCADE)
       status = models.CharField(choices=[('todo', '待办'), ('done', '完成')])
       changed_at = models.DateTimeField(auto_now_add=True)

4. **views.py (tasks应用)**:

   from django.shortcuts import render, get_object_or_404
   from .models import Task, TaskHistory
   
   def task_list(request):
       tasks = Task.objects.all().order_by('-created_at')
       return render(request, 'tasks/task_list.html', {'tasks': tasks})

   def add_task(request):
       if request.method == 'POST':
           new_task = Task(title=request.POST['title'], description=request.POST['description'],
                           assigned_to=request.user)
           new_task.save()
           return redirect('task_list')
       else:
           return render(request, 'tasks/add_task.html')

   def update_status(request, pk):
       task = get_object_or_404(Task, pk=pk)
       history_entry = TaskHistory(task=task, status=task.status)
       history_entry.save()
       task.status = request.POST['status']
       task.save()
       return redirect('task_list')

5. **urls.py (tasks应用) 和 main urls.py (task_manager项目)**:

   # tasks/urls.py
   from django.urls import path
   from . import views
   
   urlpatterns = [
       path('', views.task_list, name='task_list'),
       path('add/', views.add_task, name='add_task'),
       path('<int:pk>/update/<str:status>/', views.update_status, name='update_status'),
   ]
   
   # main project's urls.py
   from django.contrib import admin
   from django.urls import include, path

   urlpatterns = [
       path('admin/', admin.site.urls),
       path('tasks/', include('tasks.urls')),
   ]

6. **templates (tasks应用) - 添加HTML文件如task_list.html, add_task.html等**:
创建对应的模板文件，展示任务列表、添加任务表单和更新任务状态的界面。

7. **运行服务器**:

   python manage.py runserver

现在你可以访问`http://localhost:8000/tasks/`查看任务管理系统的初步功能。记得根据实际需求调整和完善细节，比如权限控制、分页显示等。