在 django 中设置过滤器

Question

我想在我的应用程序中设置一个过滤器...我想让我的过滤器以增量方式完成，有点像 this site 运行的过滤器。到目前为止，我的过滤器视图是分开的（有没有办法将过滤逻辑组合到一个视图中？）我想我需要一些方法来保存所选的过滤器（可能是会话......但我不确定这个怎么做）。我的代码如下：

def year_filter(request, year):   
vehicle_query = Vehicle.objects.filter(common_vehicle__year__year__exact=year).exclude(status__status='Incoming')
vehicle_list = vehicle_query.order_by('common_vehicle__series__model__manufacturer__manufacturer', 'common_vehicle__series__model__model', 'common_vehicle__year')

vehicle = paginate(request, vehicle_list)

year_count = vehicle_query.order_by('-common_vehicle__year__year').values('common_vehicle__year__year').annotate(count=Count('id'))
make_count = vehicle_query.order_by('common_vehicle__series__model__manufacturer__manufacturer').values('common_vehicle__series__model__manufacturer__manufacturer').annotate(count=Count('id'))
style_count = vehicle_query.order_by('common_vehicle__body_style__style').values('common_vehicle__body_style__style').annotate(count=Count('id'))
color_count = vehicle_query.order_by('exterior_colour__exterior_colour').values('exterior_colour__exterior_colour').annotate(count=Count('id'))

return render_to_response('vehicles.html', {'vehicle': vehicle, 'make_count': make_count, 'year_count': year_count, 'style_count': style_count, 'color_count': color_count,})

def make_filter(request, make):       
vehicle_query = Vehicle.objects.filter(common_vehicle__series__model__manufacturer__manufacturer=make).exclude(status__status='Incoming')
vehicle_list = vehicle_query.order_by('common_vehicle__series__model__manufacturer__manufacturer', 'common_vehicle__series__model__model', 'common_vehicle__year')

vehicle = paginate(request, vehicle_list)

year_count = vehicle_query.order_by('-common_vehicle__year__year').values('common_vehicle__year__year').annotate(count=Count('id'))
make_count = vehicle_query.order_by('common_vehicle__series__model__manufacturer__manufacturer').values('common_vehicle__series__model__manufacturer__manufacturer').annotate(count=Count('id'))
series_count = vehicle_query.order_by('common_vehicle__series__series').values('common_vehicle__series__series').annotate(count=Count('id'))
style_count = vehicle_query.order_by('common_vehicle__body_style__style').values('common_vehicle__body_style__style').annotate(count=Count('id'))
color_count = vehicle_query.order_by('exterior_colour__exterior_colour').values('exterior_colour__exterior_colour').annotate(count=Count('id'))

return render_to_response('vehicles.html', {'vehicle': vehicle, 'make_count': make_count, 'series_count': series_count, 'year_count': year_count, 'style_count': style_count, 'color_count': color_count,})

def series_filter(request, model):
vehicle_query = Vehicle.objects.filter(common_vehicle__series__series=model).exclude(status__status='Incoming')
vehicle_list = vehicle_query.order_by('common_vehicle__series__series', 'common_vehicle__series__model__model', 'common_vehicle__year')

vehicle = paginate(request, vehicle_list)

year_count = vehicle_query.order_by('-common_vehicle__year__year').values('common_vehicle__year__year').annotate(count=Count('id'))
make_count = vehicle_query.order_by('common_vehicle__series__model__manufacturer__manufacturer').values('common_vehicle__series__model__manufacturer__manufacturer').annotate(count=Count('id'))
style_count = vehicle_query.order_by('common_vehicle__body_style__style').values('common_vehicle__body_style__style').annotate(count=Count('id'))
color_count = vehicle_query.order_by('exterior_colour__exterior_colour').values('exterior_colour__exterior_colour').annotate(count=Count('id'))

return render_to_response('vehicles.html', {'vehicle': vehicle, 'make_count': make_count, 'year_count': year_count, 'style_count': style_count, 'color_count': color_count,})

def body_filter(request, body):
vehicle_query = Vehicle.objects.filter(common_vehicle__body_style__style=body).exclude(status__status='Incoming')
vehicle_list = vehicle_query.order_by('common_vehicle__series__model__manufacturer__manufacturer', 'common_vehicle__series__model__model', 'common_vehicle__year')

vehicle = paginate(request, vehicle_list)

year_count = vehicle_query.order_by('-common_vehicle__year__year').values('common_vehicle__year__year').annotate(count=Count('id'))
make_count = vehicle_query.order_by('common_vehicle__series__model__manufacturer__manufacturer').values('common_vehicle__series__model__manufacturer__manufacturer').annotate(count=Count('id'))
style_count = vehicle_query.order_by('common_vehicle__body_style__style').values('common_vehicle__body_style__style').annotate(count=Count('id'))
color_count = vehicle_query.order_by('exterior_colour__exterior_colour').values('exterior_colour__exterior_colour').annotate(count=Count('id'))

return render_to_response('vehicles.html', {'vehicle': vehicle, 'make_count': make_count, 'year_count': year_count, 'style_count': style_count, 'color_count': color_count,})

def color_filter(request, color):
vehicle_query = Vehicle.objects.filter(exterior_colour__exterior_colour=color).exclude(status__status='Incoming')
vehicle_list = vehicle_query.order_by('common_vehicle__series__model__manufacturer__manufacturer', 'common_vehicle__series__model__model', 'common_vehicle__year')

vehicle = paginate(request, vehicle_list)

year_count = vehicle_query.order_by('-common_vehicle__year__year').values('common_vehicle__year__year').annotate(count=Count('id'))
make_count = vehicle_query.order_by('common_vehicle__series__model__manufacturer__manufacturer').values('common_vehicle__series__model__manufacturer__manufacturer').annotate(count=Count('id'))
style_count = vehicle_query.order_by('common_vehicle__body_style__style').values('common_vehicle__body_style__style').annotate(count=Count('id'))
color_count = vehicle_query.order_by('exterior_colour__exterior_colour').values('exterior_colour__exterior_colour').annotate(count=Count('id'))

return render_to_response('vehicles.html', {'vehicle': vehicle, 'make_count': make_count, 'year_count': year_count, 'style_count': style_count, 'color_count': color_count,})

Answer 1

这种逻辑就是managers 的用途。即使您决定不使用管理器，您也应该以您熟悉的其他方式分解出通用代码。 （更喜欢过程编程？编写一个实用函数。熟悉 OOP？创建可调用的基于类的视图，这些视图继承自包含过滤逻辑的类。）如果您发现自己像这样复制和粘贴代码，这表明您正在很快就会遇到麻烦。

Answer 2

你写了一个经理。从您的示例中，它至少需要一种方法用于vehicle_query，一种方法用于.annotate(count=Count('id'))，并且可能需要一些用于重复的order_by()s。

如果你需要嵌套方法，这样你就可以做到vehicle_query(year).with_counts()和with_counts().vehicle_query(year)，你也需要制作自己的QuerySet，即：继承QuerySet，添加方法，然后使用它管理器中的查询集，并将管理器中的方法映射到查询集中的方法。

from django.db import models
from django.db.models.query import QuerySet

class VehicleQuerySet(QuerySet):
    def vehicle_query(self, year):
        return self.filter(common_vehicle__year__year__exact=year).exclude(status__status='Incoming')

class VehicleManager(models.Manager):
    def get_query_set(self):
        return VehicleQuerySet(self.model)

    def vehicle_query(self, year):
        return self.get_query_set().vehicle_query(year)

class WhateverModel(models.Model):
    ...
    objects = models.Manager() # keeping the default manager
    smart_objects = VehicleManager() # additional manager

那么在你看来：

vehicle_query = Vehicle.smart_objects.vehicle_query(year)