程序员最近都爱上了这个网站  程序员们快来瞅瞅吧！  it98k网:it98k.com

我想为命名的问题创建基本模型Question ，并通过任何其他问题类型对其进行扩展：

class Question(models.Model):
    questionnaire = models.ForeignKey(to='Questionnaire', on_delete=models.CASCADE, related_name='questions')
    question = models.TextField()
    description = models.TextField(null=True, blank=True)
    media = models.FileField(upload_to='medias', blank=True, null=True)
    is_required = models.BooleanField(default=False)

    def __str__(self):
        return f'{self.questionnaire.name} - {self.question}'

我想像这样扩展它：

class OptionalQuestion(Question):
    multiple_choice = models.BooleanField(default=False)
    additional_options = models.BooleanField(default=False)
    # If multiple_choice is True, then max_selected_options and min_selected_options will be used
    max_selected_options = models.IntegerField(null=True, blank=True)
    min_selected_options = models.IntegerField(null=True, blank=True)

    # If additional_options is True, then all_options and nothing_selected will be used
    all_options = models.BooleanField(default=False, null=True, blank=True)
    nothing_selected = models.BooleanField(default=False, null=True, blank=True)

    def save(self, *args, **kwargs):
        if not self.multiple_choice:
            self.max_selected_options = None
            self.min_selected_options = None
        if not self.additional_options:
            self.all_options = None
            self.nothing_selected = None
        if self.nothing_selected or self.all_options:
            self.all_options = False
            self.multiple_choice = False
        super().save(*args, **kwargs)

在第一次创建迁移时一切都很好但是下次 Django 要我为'question_ptr'字段提供默认值时我什至不知道这个字段是什么

我尝试将基类抽象化，并且在进行迁移时 Django 向我显示了很多这样的错误：

question_app.TextAnswerQuestion.questionnaire: (fields.E305) Reverse query name for 'question_app.TextAnswerQuestion.questionnaire' clashes with reverse query name for 'question_app.DropDownQuestion.questionnaire'.
        HINT: Add or change a related_name argument to the definition for 'question_app.TextAnswerQuestion.questionnaire' or 'question_app.DropDownQuestion.questionnaire'.
question_app.TextAnswerQuestion.questionnaire: (fields.E305) Reverse query name for 'question_app.TextAnswerQuestion.questionnaire' clashes with reverse query name for 'question_app.NumberAnswerQuestion.questionnaire'.
        HINT: Add or change a related_name argument to the definition for 'question_app.TextAnswerQuestion.questionnaire' or 'question_app.NumberAnswerQuestion.questionnaire'.
question_app.TextAnswerQuestion.questionnaire: (fields.E305) Reverse query name for 'question_app.TextAnswerQuestion.questionnaire' clashes with reverse query name for 'question_app.OptionalQuestion.questionnaire'.
        HINT: Add or change a related_name argument to the definition for 'question_app.TextAnswerQuestion.questionnaire' or 'question_app.OptionalQuestion.questionnaire'.

我不知道该怎么办

解决方案

首先使问题模型抽象=真

当抽象基类中有ForeignKey关系时，每个派生类都会有这种关系。所以你不能硬编码它的related_name，因为所有派生类都会尝试在相关类上创建相同的访问器。

正如 Django 文档所建议的那样，您可以在问题模型中执行以下操作：

questionnaire = models.ForeignKey(to='Questionnaire', on_delete=models.CASCADE, related_name="%(app_label)s_%(class)s_questions")

在此处查看 Django 文档。点击这里