Django: ForeignKey过滤表单中的选定数据查询

Question

我正在使用自动结果系统am。我在models.py文件中有五个模型类。

class Student(models.Model):
    std_name=models.CharField('Student Name ', max_length=200)
    CLASS_NAME=(
        ('6','SIX'),
        ('7','SEVEN'),
        ('8','Eight'),
        ('9','Nine'),
        ('10','Ten'),
        ('Ex-10','EX-Ten'),
    )
    std_class_name=models.CharField('Class Name', max_length=7, choices=CLASS_NAME)
    std_roll_number=models.IntegerField('Roll Number')
    GENDER=(
        ('Male','Male'),
        ('Female','Female'),
    )
    std_gender=models.CharField('Gender', max_length=7, choices=GENDER)
    GROUP=(
        ('Science','Science Group'),
        ('B.Studies','Business Group'),
        ('Arts and Humatics','Arts and Humatics'),
        ('General','General'),
    )
    std_group=models.CharField('Group', max_length=17, choices=GROUP)
    pub_date = models.DateTimeField('Published', auto_now_add=True)
    std_total_subject=models.IntegerField('Total Subject', default=0)


    def __str__(self):
        return self.std_name



class ExaminationName(models.Model):
    examination_name=models.CharField('Examination Name ', max_length=100)
    exam_date=models.DateTimeField('Exam Date: ')
    pub_date = models.DateTimeField('Published', auto_now_add=True)


    def __str__(self):
        return self.examination_name

class MainSubject(models.Model):
    main_subject_name = models.CharField('Main Subject Name', max_length=100)
    main_subject_code=models.DecimalField('Main Subject Code', decimal_places=0, default=0, max_digits=10)
    subject_full_marks = models.DecimalField('Subject Full Marks', max_digits=6, decimal_places=0, default=100)
    pub_date = models.DateTimeField('Published', auto_now_add=True)

    def __str__(self):
        return self.main_subject_name



class SubjectName(models.Model):
    mainsubject = models.ForeignKey(MainSubject, on_delete=models.CASCADE)
    subject_name=models.CharField('Subject Name', max_length=100)
    subject_full_marks=models.DecimalField('Subject Full Marks',max_digits=6, decimal_places=0, default=100)
    pub_date = models.DateTimeField('Published', auto_now_add=True)

    subject_gpa_point=models.DecimalField('GPA in Subject',max_digits=4, decimal_places=2, default=0)
    subject_gpa_grade=models.CharField('GPA Grade',max_length=5, default='F')


    def __str__(self):
        return self.subject_name


class SubjectPart(models.Model):
    mainsubject = models.ForeignKey(MainSubject, on_delete=models.CASCADE)
    subjectname = models.ForeignKey(SubjectName, on_delete=models.CASCADE)
    subject_part_name=models.CharField('Subject Part', max_length=100)
    subject_part_full_marks = models.DecimalField('Full Marks', max_digits=6, decimal_places=0, default=100)
    subject_part_pass_marks = models.DecimalField('Pass Marks', max_digits=6, decimal_places=0, default=100)
    pub_date = models.DateTimeField('Published', auto_now_add=True)


    def __str__(self):
        return self.subject_part_name






class AddResult(models.Model):
    student=models.ForeignKey(Student, on_delete=models.CASCADE)
    examinationname = models.ForeignKey(ExaminationName, on_delete=models.CASCADE)
    mainsubject_name = models.ForeignKey(MainSubject, on_delete=models.CASCADE)
    subjectname = models.ForeignKey(SubjectName, on_delete=models.CASCADE)
    subjectpart = models.ForeignKey(SubjectPart, on_delete=models.CASCADE)
    subject_number=models.DecimalField('Subject Number', max_digits=6, decimal_places=0)
    pub_date = models.DateTimeField('Published', auto_now_add=True)


    def __str__(self):
        return str(self.subjectpart)

    def fail_sub(self):
        if self.subject_number < self.subjectpart.subject_part_pass_marks:
            return 'F'

我已经通过Django管理面板创建了一个MainSubject对象。我通过外键在SubjectName模型类中添加了主主题。我在SubjectName模型类中创建了两个外键。我通过Django-admin面板在SubjectPart模型中创建了任何对象，如下所示。

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然后我创建了一个AddResulForm ModelForm。但问题是，当我选择主题名称时，所有主题都显示该时间。如果我选择孟加拉作为主要主题，那么我只选择主题名称部分中的孟加拉第一部分或第二部分。但现在以这种形式显示了所有的主题。如何在Django表单中实现我的想法？

Answer 1

为此，您应该在admin.py中编写方法

您可以为模型(Subject部分)创建一个类，并为该字段实现一个方法。

你可以参考这个https://docs.djangoproject.com/en/1.11/ref/contrib/admin/

Answer 2

在Django中，你可以过滤选项集，但在前端交互中，你可能不得不重新实现表单模板html代码或表单字段。