Django的查詢，對查詢集

Question

對於此代碼檢索與後續查詢的初始查詢集：

people_pool = People.objects.filter(last_name__in = last_names) 
for first_name in first_names: 
    for person in people_pool.filter(first_name = first_name): 
     # do something with each person. 

我從Django的查詢集的理解是，查詢實際上不會，直到你「需要」的數據執行，從而可以優化鏈接的查詢集。但是，如果我沒有弄錯，那在這裏似乎對我不利;將執行的第一個查詢本質上將等同於：

People.objects.filter(last_name__in = last_names, first_name = first_name) # for the first first_name in first_names 

並且需要爲每個單個名字查詢數據庫。如果是這種情況，那麼讓Django實際檢索people_pool，然後在檢索到的python對象上運行後續篩選器，使數據庫保持獨立的正確方法是什麼？

Answer 1

爲了不辦爲每個名字一個DB查詢，唯一的辦法是做實際的過濾在Python：

people_pool = People.objects.filter(last_name__in = last_names) 
people = {} 

for person in people_pool: 
    first_name = person.first_name 
    if first_name in first_names: 
     if not first_name in people: 
      people[first_name] = [] 
     people[first_name].append(person) 

for first_name, people_first_name in people.items(): 
    for person in people_first_name: 
     # do something with each person 

如果你願意，你也可以做一些在第一循環（ for person in people_pool）。我只是在dict中添加人員，但該步驟不是必需的。