Question

我正在尝试在列表视图中实现多个属性的搜索。我不想为每个属性使用多个if-else。

这是我当前在列表视图中进行搜索的代码：

def get_queryset(self):
    city = self.request.GET.get('city_name') or ''
    user = self.request.GET.get('user_name') or ''
    if (city != '' or user!=''):
        userqueries = user.split() 
        cityqueries = city.split() 
        if len(userqueries) and len(cityqueries):
            qset1 =  functools.reduce(operator.__or__, [
                Q(first_name__icontains=query) | Q(last_name__icontains=query) for query in userqueries])
            qset2 =  functools.reduce(operator.__or__, [Q(city__name__icontains=query)  for query in cityqueries])
            object_list = self.model.objects.filter(qset1 , qset2)
        elif len(userqueries):
            qset1 =  functools.reduce(operator.__or__, [
                Q(first_name__icontains=query) | Q(last_name__icontains=query) for query in userqueries])
            object_list = self.model.objects.filter(qset1)
        elif len(cityqueries):
            qset1 =  functools.reduce(operator.__or__, [Q(city__name__icontains=query)  for query in cityqueries])

            object_list = self.model.objects.filter(qset1)
    else:
        object_list = self.model.objects.all()
    return object_list

如果我要添加一个属性：

    city = self.request.GET.get('city_name') or ''
    user = self.request.GET.get('user_name') or ''
    state = self.request.GET.get('state_name') or ''

    if (city != '' or user!='' or state!=''):
        userqueries = user.split() 
        cityqueries = city.split() 
        statequeries = state.split() 
        if len(userqueries) and len(cityqueries):
            qset1 =  functools.reduce(operator.__or__, [
                Q(first_name__icontains=query) | Q(last_name__icontains=query) for query in userqueries])
            qset2 =  functools.reduce(operator.__or__, [Q(city__name__icontains=query)  for query in cityqueries])
            object_list = self.model.objects.filter(qset1 , qset2)
        elif len(userqueries) and len(statequeries):
            qset1 =  functools.reduce(operator.__or__, [
                Q(first_name__icontains=query) | Q(last_name__icontains=query) for query in userqueries])
            qset2 =  functools.reduce(operator.__or__, [Q(city__state__name__icontains=query)  for query in statequeries])
            object_list = self.model.objects.filter(qset1 , qset2)
        elif len(userqueries):
            qset1 =  functools.reduce(operator.__or__, [
                Q(first_name__icontains=query) | Q(last_name__icontains=query) for query in userqueries])
            object_list = self.model.objects.filter(qset1)
        elif len(cityqueries):
            qset1 =  functools.reduce(operator.__or__, [Q(city__name__icontains=query)  for query in cityqueries])
            object_list = self.model.objects.filter(qset1)
        elif len(statequeries):
            qset1 =  functools.reduce(operator.__or__, [Q(city__state__name__icontains=query)  for query in statequeries])
            object_list = self.model.objects.filter(qset1)

我想将所有这些条件合并为一个：

        if len(userqueries) and len(cityqueries):

        elif len(userqueries):

        elif len(cityqueries):

Answer 1

我们最好制作一个辅助函数，该函数构造一个Q对象，该对象是多个元素的分离，例如：

from django.db.models import Q
from functools import reduce
from operator import or_

def q_or_otherwise_true(iterable, *keys):
    iterable = list(iterable)
    if iterable:
        return reduce(or_, [Q(**{key: val}) for val in iterable for key in keys])
    else:
        return Q()

这样会生成Q个对象，例如：

>>> q_or_otherwise_true(['foo'], 'col1__icontains', 'col2__icontains')
<Q: (OR: ('col1__icontains', 'foo'), ('col2__icontains', 'foo'))>
>>> q_or_otherwise_true(['foo', 'bar'], 'col1__icontains', 'col2__icontains')
<Q: (OR: ('col1__icontains', 'foo'), ('col2__icontains', 'foo'), ('col1__icontains', 'bar'), ('col2__icontains', 'bar'))>
>>> q_or_otherwise_true([], 'col1__icontains', 'col2__icontains')
<Q: (AND: )>

然后我们可以生成如下代码：

def get_queryset(self):
    city = self.request.GET.get('city_name') or ''
    user = self.request.GET.get('user_name') or ''
    userqueries = user.split() 
    cityqueries = city.split()
    return self.model.objects.filter(
        q_or_otherwise_true(userqueries, 'first_name__icontains', 'last_name__icontains'),
        q_or_otherwise_true(cityqueries, 'city__name__icontains'),
    )

之所以可行，是因为给定q_or_otherwise_true包含任何元素，或者或iterable使元素分离。如果不是，它将构造一个Q()对象，该对象在.filter(..)调用中不会过滤任何内容。因此，这意味着我们可以将这两者结合起来。

只需简单地进行额外的q_or_otherwise_true调用，就可以轻松地将该函数扩展为更多调用。

在Django中应用多属性搜索

1 个答案: