需要在Django Rest框架中为客户端生成客户端和项目代码

Question

models.py

class Client(models.Model):

    client_name=models.CharField(max_length=30,default=None)
    client_code = models.CharField(max_length=3, default=None, null=True)
    company=models.CharField(max_length=200) 
    finance_contact_email=models.EmailField(max_length=25,default=None)
    business_purpose=models.CharField(max_length=50,null=True,default=None)
    location=models.CharField(max_length=200)
    emergency_contact=models.CharField(max_length=200,null=True,default=None)
    website=models.URLField(max_length=200,null=True)
    comments=models.TextField(max_length=300,null=True, blank=True)
    start_Date = models.DateTimeField(max_length=10,null=True)
    end_Date=models.DateField(max_length=10,null=True)
 
    class Meta:
        
        db_table ='Client'
    
    def __str__(self):
        return '{}'.format(self.client_name)

#Project model
class Project(models.Model):

    project_code = models.CharField(primary_key=False, editable=False, max_length=10,default=None,null=True)
    #client_project_code = models.CharField(primary_key=False, editable=False, max_length=10,default=None,null=True)
    project_name = models.CharField(max_length=30,unique=True,default=None)
    client_code = models.ForeignKey(Client,on_delete=CASCADE,related_name="Client5",default=None, null=True) # need to get the client code instead of name but the name should be returned in client model
    client= models.ForeignKey(Client,on_delete=CASCADE,related_name="Client1",default=None)
    user=models.ManyToManyField(User,related_name='users',default=None)
    description=models.TextField()
    type=models.TextField()                                      #dropdown
    start_date = models.DateTimeField(max_length=10)
    end_date=models.DateTimeField(max_length=10)
    technical_contact_name = models.CharField(max_length=30)
    email=models.EmailField(max_length=254,default=None)
    phone = PhoneField(blank=True)
    delivery_head_contact_name=models.CharField(max_length=30)
    
    class Meta:
        
        db_table ='Project'


    def save(self, **kwargs):
        if not self.id:
            max = Project.objects.aggregate(id_max=Max('project_code'))['id_max']
            self.project_code = "{}{:03d}".format('', max if max is not None else 1)
        super().save(*kwargs)

    def __str__(self):
        return '{}'.format(str(self.client_code), str(self.project_code))

根据上面的代码，我在客户端模型中创建了一个客户端代码，我需要将客户端代码与在项目代码字段本身或新字段中自动生成的项目代码结合起来。 例如：客户代码：ICN 和项目代码：ICN001。 一件主要的事情是我希望在客户端模型中返回客户端名称，并且我需要将客户端代码从客户端模型链接到项目，我被困在该方法上，例如如何返回它？

注意：更改和字段需要反映在 django 管理门户中。

答案后更新了代码：

class Project(models.Model):

    project_code = models.CharField(primary_key=False, editable=False, max_length=10,default=None,null=True)
    #client_project_code = models.CharField(primary_key=False, editable=False, max_length=10,default=None,null=True)
    project_name = models.CharField(max_length=30,unique=True,default=None)
    #client_code = models.ForeignKey(Client,on_delete=CASCADE,related_name="Client5",default=None, null=True)
    client= models.ForeignKey(Client,on_delete=CASCADE,related_name="Client1",default=None)
    user=models.ManyToManyField(User,related_name='users',default=None)
    description=models.TextField()
    type=models.TextField()                                      #dropdown
    start_date = models.DateTimeField(max_length=10)
    end_date=models.DateTimeField(max_length=10)
    technical_contact_name = models.CharField(max_length=30)
    email=models.EmailField(max_length=254,default=None)
    phone = PhoneField(blank=True)
    delivery_head_contact_name=models.CharField(max_length=30)
    
    class Meta:
        
        db_table ='Project'

    def save(self, **kwargs):
        if not self.id:
            max = Project.objects.aggregate(id_max=Max('project_code'))['id_max']
            self.project_code = "{}{:03d}".format('', max if max is not None else 1)
        super().save(*kwargs)

    def __str__(self):
        if self.client is not None:
            return f'{self.client.client_code}{self.project_code}'
        else:
            return self.project_code

根据答案，我更新了代码并删除了客户端代码字段，因为它是客户端的重复列，当我尝试在没有客户端代码字段的情况下输入详细信息时，我收到错误“ValueError at /admin” /应用程序/项目/添加/ “str”类型的对象的未知格式代码“d””。您能帮我解决这个错误吗？

Traceback 的屏幕截图：

Answer 1

您可以使用：

class Project(models.Model):
    # …
    
    def __str__(self):
        if self.client_code is not None:
            return f'{self.client_code.client_code}{self.project_code}'
        else:
            return self.project_code

但是将您的foreferkey交给client name client> client_code：这将返回client client> client> client> client> client> client> client> client> client> client> client> client> name ，这并不多。 对象，而不是其名称，也不是其代码。 客户端因此，可能比 client_code 更好。