Django-如何使用独立的列创建模式

Question

我是Django的新手，我必须创建new页面，它需要以下输入:位置、技术和服务。第一个网页应该选择一个位置类型，并在此基础上进入下一个页面，根据位置选择该技术。第三个web页面基于前面选择的技术和位置选择服务(这将是两个.For的交集)，我必须创建模式，其中每个位置都可以有多个技术和服务，其中两者都是相互独立的，每种技术都有多个服务。

eg: loc1_tech->tech1,tech2
    loc2_service->service1,service2,service3
    tech1_service->service1,service2
    tech_service2->service3,service4,service5

如果选择loc1，则下一个网页显示tech1和tech2，如果选择tech2，则第三个web页面只显示service3，这是loc1和tech2服务的交集。我计划创建3种模式-- loc_tech、loc_services、tech_services in models.py。这是解决这个问题和创建模式的有效方法吗？另外，如何为第三个网页找到web服务的交叉点？

Answer 1

使用外键的组合是models.py和related_name属性在views.py中可能会帮助您解决问题。

models.py应该类似于：

from django.utils.translation import ugettext_lazy as _

class Location(models.Model):
    name = models.CharField(_('Location Name') , max_length = 32)
    #other fileds you may want to put.

class Technology(models.Model):
    name = models.CharField(_('Technology Name') , max_length = 32)
    location = models.ForeignKey(Location , related_name="technologies")
    #other fileds you may want to put.

class Service(models.Model):
    name = models.CharField(_('Service Name') , max_length = 32)
    location = models.ForeignKey(Technology , related_name="services")
    #other fileds you may want to put.

现在有意见：

def get_technologies(request , location_pk=None):
    location = Location.objects.get(pk = location_pk)
    technologies = location.technologies.all()
    #technologies queryset gives you the all the technologies in the location chosen. 
    #return a HttpResponse()

def get_services(request , technology_pk=None):
    technology = Technology.objects.get(pk = technology_pk)
    services = technology.services.all()
    #services queryset gives you the all the services in the technology(which comes fromt he location chosen earlier) chosen.
    #return a HttpResponse()

注意：、technology_pk和location_pk将由客户端作为参数发送。他们必须被你的urls.py控告。

当然，您必须配置urls.py以接受参数technology_pk和location_pk。另外，你也可以用，

location_pk = request.GET.get('location_pk' , None)
location = Location.objects.get(pk = location_pk)

客户端在request.GET.get('location_pk' , None)中发送‘request.GET.get('location_pk' , None)’的位置。

编辑：

对于发送到服务器的多个位置或技术实例，方法可能有所不同。正如您所说的，我们必须使用filter()而不是get()。

为了获得技术，

def get_technologies(request):
    locations = request.POST.getlist('location[]')
    #Above, you have to obtain the list of locations that are selected by the user. Request method can be GET as well.  
    locations_selected_queryset = Location.objects.filter(pk__in = locations)
    #For the above statement to work, the list: "locations" should contain the "pk" values of all the locations selected by the user.
    result_technologies = list()
    for location in location_selected_queryset:
        technologies_for_one_location = location.technologies.all()
        result_technologies.append(technologies_for_one_location)
        #Change the variable names best suited to you. I tried to name them to give more understanding.

现在，result_technologies将有不同查询集()列表的列表，该列表由用户选择的所有位置所带来的查询集组成。如果你把它打印在控制台上，它看起来就像

[<技术："str值“>，.，技术："str值”>，技术："str值“>，……]

查询集列表。现在，您将遇到加入查询集获取的问题，因为查询集列表会造成混乱。

from itertools import chain
#In your views.py, inside the function get_technologies()
def get_technologies(request):
    #...
    #...
    for location in location_queryset:
        technologies_for_one_location = location.technologies.all()
        result_technologies.append(technologies_for_one_location)

    final_result = list(chain(*result_technologies))        
    #final_result will be a single list with all the querysets you want.

希望这能有所帮助。谢谢。