从列表中删除具有相关相关模型的对象

Question

我相信从问题中很难理解问题，所以我会提供一个答案。

我与我的型号之间存在以下关系：Answer属于Question属于Page。我有一个答案列表：[<Answer: 1>, <Answer: 2>, ...]。

现在我想删除全部属于不同问题的答案属于相同页面。

如果，例如，我的答案列表包含以下（细节增加了清晰度）：[<Answer: Q1P1>, <Answer: Q1P1>, <Answer: Q1P2>, <Answer: Q2P2>]则只有最后2个答案应该从列表中删除，因为他们都属于属于同一个不同的问题页。前两个答案仍然存在，因为虽然他们的问题属于同一页面，但问题与并无不同。

我的模型大致是这样的：

class Page(models.Model): 
    pass 

class Question(models.Model): 
    page = models.ForeignKey(Page) 

class Answer(models.Model): 
    question = models.ForeignKey(Question) 

我怎样才能做到这一点？

Answer 1

更新2：

比方说，我们有一个answers列表。

 
# 1. Let's find out the pages: 
pages = set([]) 
for a in answers: 
pages.add(a.question.page) 
pages = list(pages) 

# 2. Now for each page, 
for p in pages: 
    # 2.a. find out the answers that belong to this page 
    same_page_answers = [a for a in answers if a.question.page = p] 
    # 2.b. find out the questions of these answers 
    same_page_questions = set([]) 
    for a in same_page_answers: 
    same_page_questions.add(a.question) 
    same_page_questions = list(same_page_questions) 

    # 3. now we will check to see if each question appears at least twice 
    for q in same_page_questions: 
    same_page_question_answers = [a for a in same_page_answers if a.question=q] 
    if len(same_page_question_answer) < 2: 
     # Ok so the same_page_question_answers need to be removed from our initial answers 
     answers = [a for a in answers if a not in same_page_question_answer] 
     # actually if we are here same_page_question_answer will be an array with 1 element but in any case 

使用你的例子

 

answers = [A1: Q1P1, A2: Q1P1, A3: Q1P2, A4: Q2P2] 

pages = [P1, P2] 

inside for loop for P1: 
same_page_answers = [A1, A2] 
same_page_questions = [Q1, Q1] 
inside for loop for Q1: 
    len == 2 - we won't remove anything 


inside for loop for P2: 
same_page_answers = [A3, A4] 
same_page_questions = [Q1, Q2] 
inside for loop for Q1: 
    same_page_question_answers = [A3] 
    len = 1 - we will remove [A3] from answers 
inside for loop for Q2: 
    same_page_question_answers = [A4] 
    len = 1 - we will remove [A4] from answers 

answers = [A1,A2] 

希望它的工作现在:)