Django的filterset - 一對多查詢

Question

我有一個一對多的關係模型如下：

class Client(models.Model): 
    name = models.CharField.... 
    ... 

class Contract(models.Model): 
    client = models.ForeignKey(Client) 
    type = models.IntegerField() 
    start_date = models.DateField(null=True, blank=True) 
    ... 

我想構建一個高效的查詢集返回其最新（即一個與最近開始的所有客戶端日期）contract.type等於5

我怕我掙扎周圍試圖解決這一個。

任何人都可以幫忙嗎？

如果它不是可能的，那麼我正在考慮加入到客戶端的字段是一對一的關係，以最新的合同，這每一個合同的修改時間保持。然後，我可以簡單地使用該字段進行搜索。

最終我去下面的，如果這個可以進行優化，那麼請讓我知道 - TA。

# this function is called by django-filter 
    # its purpose is to remove any clients where the contract with the most recent start date 
    # does not have a type that matches the value parameter 
    def filter_contract_type(self, queryset, name, value): 
     # for each client get the contract with the latest start date 
     # if that contract has a type that matches the value parameter, then hold on to the pk of its parent 
     # finally strip out any clients that are not in this list, from the queryset django-filter passed in and then return it 
     client_ids = [] 
     value = int(value) 
     for client in queryset: 
      con = Contract.objects.filter(client=client).order_by('start_date').last() 
      if con is not None and con.type == value: 
       client_ids.append(con.client.id) 

     return queryset.filter(pk__in=client_ids) 

Answer 1

對不起因爲我沒有得到你的更好的方法，但你可以嘗試：

# Get ez list 
Cs = Contract.objects.filter(type = 5).order_by(start_date) 
# and run the loop to get the 5 dif cl id 
cl_ids= [] 
num = 0 
for c in Cs: 
    if c.client_id not in cl_ids: 
     cl_ids.append(c.client_id) 
     if len(cl_ids) > 4: 
      break