如何使用Django Rest Framework将多个模型序列化为一个用于层次结构的序列化器？

Question

我有四个模型，我需要将三个序列化为一个API。 我可以让各个序列化器按预期工作，但是当它们组合成一个时，我得不到我期望看到的结果。

models.py

class President(models.Model):
    name = models.CharField('Name', max_length=50,)
    staff = models.ManyToManyField('Member',)
    def __str__(self):
        return self.name

"""
user creates a new member in this model below
if a new member is an employee, the object is copied into the Employee model
    and the user chooses the manager of the employee in the manager field
if a new member is a manager, the object is copied into the Manager model
"""
class Member(models.Model):
    president = models.ForeignKey(
        President, on_delete=models.CASCADE, related_name='members',
    )
    manager = models.ForeignKey(
        'Manager', on_delete=models.CASCADE, related_name='manager',
    )
    name = models.CharField('Name', max_length=50,)
    email = models.EmailField('Email Address',)
    title = models.CharField('Title', max_length=50,)
    staff_type = (
        ('Manager', 'Manager'),
        ('Employee', 'Employee'),
    )
    def __str__(self):
        return self.name

class Employee(models.Model):
    president = models.ForeignKey(
        President, on_delete=models.CASCADE, related_name='employeePresident'
    )
    manager = models.ForeignKey(
        'Manager', on_delete=models.CASCADE, related_name='employeeManager'
    )
    name = models.CharField('Name', max_length=50,)
    email = models.EmailField('Email Address',)
    title = models.CharField('Title', max_length=50,)
    def __str__(self):
        return self.name

class Manager(models.Model):
    president = models.ForeignKey(
        President, on_delete=models.CASCADE, related_name='managerPresident'
    )
    name = models.CharField('Name', max_length=50,)
    department = models.CharField('Department', max_length=50,)
    def __str__(self):
        return self.name

serializers.py

class PresidentSerializer(serializers.ModelSerializer):
    class Meta:
        model = President
        fields = '__all__'
class EmployeeSerializer(serializers.ModelSerializer):
    class Meta:
        model = Employee
        fields = '__all__'
class ManagerSerializer(serializers.ModelSerializer):
    members = EmployeeSerializer(many=True,)
    class Meta:
        model = Manager
        fields = ('president', 'name', 'department', 'members')

到目前为止，所有这些序列化程序都按预期工作。 ManagerSerializer在树视图中公开管理器的名称及其下面的员工。

但是，员工不一定必须在经理之下，例如他们可以直接向总统对象报告，就像总统助理一样。

我如何将这三个序列化器合并到一个我的API将如下所示：

{
    "name": "Presidents Name",
    "staff": [
        {
            "name": "Employee No Manager",
            "title": "Presidents Asst"
        },
        {
            "name": "John Doe",
            "title": "Finance Manager",
            "employees": [
                {
                    "name": "Mary Simpson",
                    "title": "Finance Asst"
                }
            ]
        }
}

不确定我的模型设计中是否需要更改某些内容，而总统模型可以同时采用Employee和Manager模型。 任何帮助将不胜感激。

Answer 1

我会将每个员工的db结构简化为1个类（以及2个额外的db规范化类）：

class JobTitle(models.Model):
    title = models.CharField('Title', max_length=50)

    def __str__(self):
        return self.title


class Department(models.Model):
    name = models.CharField('Department', max_length=50)

    def __str__(self):
        return self.name


class Employee(models.Model):
    name = models.CharField('Name', max_length=50)
    boss = models.ForeignKey("Employee", on_delete=models.CASCADE, related_name="staff", blank=True, null=True)
    department = models.ForeignKey("Department", on_delete=models.CASCADE)
    email = models.EmailField('Email Address')
    title = models.ForeignKey("JobTitle", on_delete=models.CASCADE)

    @property
    def is_president(self):
        return self.boss is None

    @property
    def is_manager(self):
        return len(self.staff) > 0

    def __str__(self):
        return self.name

然后你可以从这个答案中使用递归序列化器：

class RecursiveField(serializers.Serializer):
    def to_representation(self, value):
        serializer = self.parent.parent.__class__(value, context=self.context)
        return serializer.data

class EmployeeSerializer(serializers.ModelSerializer):
    staff = RecursiveField(many=True)

    class Meta:
        model = Employee
        fields = '__all__'