计数内多对多领域的Django

Question

假设我有以下型号：

class Analysis(Model): 
    experts = ManyToManyField(Expert, 
           related_name='analysis', 
           through='AnalysisExpert') 


class AnalysisExpert(Model): 
    analysis = ForeignKey(Analysis) 
    expert = ForeignKey(Expert 

    questions = ManyToManyField(Question, through='ExpertQuestion') 

class ExpertQuestion(Model): 
    expert = ForeignKey(AnalysisExpert, related_name="expert_comparisons") 

    question = ForeignKey('Question') 

它看起来像我有嵌套ManyToManyField。分析 - >专家 - >问题

什么是计算特定分析问题数量的最有效方法？

Answer 1

您可以使用values_list计算单个分析对象的问题数量。

analysis_obj.experts.all().values_list("question").count() 

上面的查询测试，下面的模型：

class Question(models.Model): 
    question = models.CharField(max_length=50) 


class Expert(models.Model): 
    question = models.ManyToManyField(Question, 
           related_name='questions') 

class Analysis(models.Model): 
    experts = models.ManyToManyField(Expert, 
        related_name='analysis')