使用Django管理自定义列

Question

我有一个模型叫做 Data，它和一个表格关联，表格的内容是这样的（模型 Data 里面只有整数类型的字段）：

subject | year | quarter | sales |
----------------------------------
   1    | 2010 |   1     | 20    |
   1    | 2010 |   2     | 100   |
   1    | 2010 |   3     | 100   |
   1    | 2010 |   4     | 20    |
   1    | 2011 |   1     | 30    |
   1    | 2011 |   2     | 50    |
   1    | 2011 |   4     | 40    |
   2    | 2010 |   1     | 30    |
   2    | 2010 |   2     | 20    |
 [..-GO ON this way...]

我想在django-admin中创建一个只读的表格，里面有这些列（当前年份 = 2011, 季度 = 1）

subject | sales current year | sales current quarter | sales last year | sales current quarter last year |
----------------------------------------------------------------------------------------------------------
  1     |  110               |  30                   |  240            |  20
[AND SO ON]

问题是：这可以通过django-admin实现吗？该怎么做呢？

Answer 1

像这样的代码应该可以工作（不过还没测试过）：

# models.py
class Data(models.Model):
    year = models.DateField()
    sales = models.IntegerField()
    # ...

    def sales_current_year(self):
        return self.model._default_manager.get_queryset().filter(year=2012).annotate(Sum('sales'))

 # admin.py
 class DataAdmin(admin.ModelAdmin):
      list_display = ('sales_current_year',)

Answer 2

你可以在你的 Model 或 ModelAdmin 中使用方法作为 list_display 的项目。具体可以参考这个链接：https://docs.djangoproject.com/en/dev/ref/contrib/admin/#django.contrib.admin.ModelAdmin.list_display

因为这些方法在管理界面之外也可能有用，所以我建议把它们添加到你的 Model 中。

from django.db.models import Sum

class Data(models.Model):
    ...

    # Method used by `get_current_year_sales` and `get_last_year_sales`
    # to stay DRY. Not for use directly in admin.
    def get_year_sales(self, year):
        qs = self.model._default_manager.filter(year=year)
        sales_agg = qs.aggregate(Sum('sales'))
        return sales_agg['sales__sum']

    # Method used by `get_current_quarter_sales` and `get_last_quarter_sales`
    # to stay DRY. Not for use directly in admin.
    def get_quarter_sales(self, year, quarter):
        qs = self.model._default_manager.filter(year=year, quarter=quarter)
        sales_agg = qs.aggregate(Sum('sales'))
        return sales_agg['sales__sum']

    def get_current_year_sales(self):
        return self.get_year_sales(datetime.now().year)
    get_current_year_sales.short_description = 'Sales (Current Year)'

    def get_last_year_sales(self):
        return self.get_year_sales(datetime.now().year-1)
    get_last_year_sales.short_description = 'Sales (Last Year)'

    def get_current_quarter_sales(self):
        # Determine current quarter logic here as `current_quarter`
        # `quarter_year` will likely be same as current year here,
        # but will need to be calculated for previous quarter
        return self.get_quarter_sales(quarter_year, current_quarter)
    get_current_quarter_sales.short_description = 'Sales (Current Quarter)'

    def get_current_quarter_sales(self):
        # Logic here to determine last quarter as `last_quarter`
        # Logic to determine what year last quarter was in as `quarter_year`
        return self.get_quarter_sales(quarter_year, last_quarter)
    get_last_quarter_sales.short_description = 'Sales (Last Quarter)'

short_description 属性决定了在管理界面中这些方法的行标题会显示什么。所以，一旦你把这些都设置好，就只需要像下面这样修改你的 ModelAdmin 的 list_display 属性：

class DataAdmin(admin.ModelAdmin):
    ...
    list_display = ('subject', 'get_current_year_sales', 'get_last_year_sales', 'get_current_quarter_sales', 'get_last_quarter_sales')