Question

我是django初学者，所以代码可能是基本的或错误的，但无论如何...... 我有以下型号：

 from django.db import models
    from django.conf import settings

    GRADE_CHOICES = (
        ('1', '1'),
        ('2', '2'),
        ('3', '3'),
        ('4', '4'),
        ('5', '5'),
        ('6', '6'),
        ('7', '7'),
        ('8', '8'),
        ('9', '9'),
        ('10', '10'),
    )
    class Professor(models.Model):
        first_name = models.CharField(max_length=20)
        last_name = models.CharField(max_length=30)

        def __str__(self):
            rta = self.first_name+" "+self.last_name
            return rta

    class Student(models.Model):
        first_name = models.CharField(max_length=20, blank=False, null=False)
        last_name = models.CharField(max_length=30, blank=False, null=False)

        def __str__(self):
            rta = self.first_name+" "+self.last_name
            return rta

    class Subject(models.Model):
        first_name = models.CharField(max_length=50)
        students = models.ManyToManyField(Student, blank=True)
        professors = models.ManyToManyField(Professor, blank=True)

        def __str__(self):
            return self.first_name

    class Grade(models.Model):
        value = models.CharField(choices=GRADE_CHOICES, max_length= 2)
        subject = models.ForeignKey(Grade, on_delete=models.CASCADE, related_name='fk_grade')
        student = models.ForeignKey(Student, on_delete=models.CASCADE, related_name='fk_student')

        def __str__(self):
            return self.value

要添加成绩，我需要选择主题和学生，所以我想根据他们所属的主题过滤学生。如果学生不在该科目中，则不应出现在列表中。

我正在使用django 1.11和python 2.7。

Answer 1

您的对象Subject不应与Student和Subject相关联，而应与Student和class Professor(models.Model): # ... class Student(models.Model): # ... professors = models.ManyToManyField(Person, through='Subject') class Subject(models.Model): name = models.CharField(max_length=50) student = models.ForeignKey(Student, on_delete=models.CASCADE) professor = models.ForeignKey(Professor, on_delete=models.CASCADE) value = models.CharField(choices=GRADE_CHOICES, max_length= 2)之间的关系相关联。有些人喜欢：

[
    { "$group": {
        "_id": { 
            "year": { "$year": "$date" },
            "type": "$type",
            "color": "$color"
        },
        "count": { "$sum": "$soldFor" }
    } },
    { "$group": {
        "_id": {
            "year": "$_id.year",
            "type": "$_id.type"
        },
        "counts": {
            "$push": {
                "k": "$_id.color",
                "v": { "sum": "$count" }
            }
        }
    } },
    { "$addFields": {
        "counts": { "$arrayToObject": "$counts" }
    } },
    { "$group": {
        "_id": "$_id.year",
        "counts": {
            "$push": {
                "k": "$_id.type",
                "v": "$counts"
            }
        }
    } },
    { "$addFields": {
        "counts": { "$arrayToObject": "$counts" }
    } },
    { "$group": {
        "_id": null,
        "counts": {
            "$push": {
                "k": { "$substr": ["$_id", 0, -1 ]},
                "v": "$counts"
            }
        }
    } },
    { "$replaceRoot": { 
        "newRoot": { 
            "$mergeObjects": [ 
                { "$arrayToObject": "$counts" }, 
                "$$ROOT" 
             ] 
        } 
    } },
    { "$project": { "counts": 0 } }
]

Django管理员过滤外键组合框

1 个答案: