1

我相信很难从问题中理解问题，所以我会提供一个答案。

我的模型之间有以下关系：AnswerBelongsTo QuestionBelongsTo Page。我有一个答案列表：[<Answer: 1>, <Answer: 2>, ...]。

现在我想删除属于同一页面的不同问题的所有答案。

例如，如果我的答案列表包含以下内容（为清楚起见添加了详细信息）：[<Answer: Q1P1>, <Answer: Q1P1>, <Answer: Q1P2>, <Answer: Q2P2>]那么只有最后两个答案应该从列表中删除，因为它们都属于属于同一页面的不同问题。前两个答案仍然存在，因为尽管他们的问题属于同一页面，但问题并没有不同。

我的模型大致如下所示：

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？

4

1 回答 1

1

Update 2:

Let's say that we have an answers list.

# 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

Using your example

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]

Hope it's working now :)

于 2013-10-17T15:28:33.607 回答