Django 。我如何优化数据库查询？

Question

我有两个模型:

class Status(models.Model): 

     CHOISES = ( 
         ('new', 'New'), 
         ('in_progress', 'InProgress'), 
         ('on_review', 'OnReview'), 
         ('tested', 'Tested'), 
         ('delivered', 'Delivered') 
     ) 

    status_type = models.CharField( 
    max_length=11, 
    choices=CHOISES, 
    primary_key=True) 

class Task(models.Model):
    name = models.CharField(max_length=200, blank=False)
    status = models.ForeignKey(status)

我的部分观点:

def task_list(request):

    all_tasks = Task.objects.all()
    tasks = {}

    tasks['new'] = all_tasks.filter(status_id='new')
    tasks['in_progress'] = all_tasks.filter(status_id='in_progress')
    tasks['on_review'] = all_tasks.filter(status_id='on_review')
    tasks['tested'] = all_tasks.filter(status_id='tested')
    tasks['delivered'] = all_tasks.filter(status_id='delivered')
....

我的模板的一部分:

{% for item in new %}
    <div id="{{ item.pk }}">
        {{ item.name }}
    </div>
{% endfor %}
</div>
{% for item in in_progress %}
    <div id="{{ item.pk }}">
        {{ item.name }}
    </div>
{% endfor %}  
.....      

问题是，有没有办法优化我所有的查询集，或者不可能为一个数据库调用选择五个过滤器？
据我所知，如果我只在 View 中保存此调用 all_tasks = Task.objects.all() 然后将逻辑放入模板中，如下所示:

{% for item in all_task %}
{% if item.status_id == "new" %}
....

它也将是 exaclty 五个电话
希望我的问题不是太宽泛

Answer 1

只需按 View 中的状态对任务进行分组:

from itertools import groupby

def task_list(request):
    all_tasks = Task.objects.select_related('status').order_by('status')
    tasks = {status: list(tasks)
             for status, tasks
             in groupby(all_tasks, lambda x: x.status)}

并在您的模板中使用它们，例如:

{% for task in tasks.new %}
  {{ task }}
{% endfor %}