Question

在下面的代码中，由于某种原因，在使用外键作为项目名称之后，在def __str__(self):部分的第二个位置，就像上面所说的那样 return self.Project + ' (' + self.Situation_Type + ') ' + ' [' + self.Status + '] '的{{1}}，它告诉我一个错误，

self.Project

class 'Project' does not define '_add_', so the '+' operator cannot be used on its instances

自从出现此错误以来，“我的项目”页面一直没有显示在列表中，但是它说有1个项目。可能是什么问题？

This inspection detects names that should resolve but dont. Due to dynamic dispatch and ducttyping, this is possible in a limited but useful number of cases. Top-level and class level items are supported better than instance items.

def send_mail（admin，ass）： email = EmailMessage（'对Task所做的更改'，'对您的Task报告之一进行了更改，我们在此要求您尽早对其进行查看。'，to = [admin，ass]） email.send（）

from django.db import models

# Create your models here.
from django.contrib.auth.models import User
from django.db import models
from django.core.mail import EmailMessage

# Create your models here.

class Project(models.Model):
   STATUS_CHOICE = (
       ('Project Manager', 'Project Manager'),
       ('Technician', 'Technician'),
       ('Tester', 'Tester')
   )
   STATUS_CHOICE_1 = (
       ('Work Assigned', 'Work Assigned'),
       ('Work in Progress', 'Work in Progress'),
       ('Testing', 'Testing'),
       ('Completed', 'Completed')
   )
   Project_Name = models.CharField(max_length=100)
   Project_Description = models.CharField(max_length=100)
   Admin_Name = models.ForeignKey(User, on_delete=models.CASCADE, related_name='User.Admin_Name_users+')
   Admin_Mail_ID = models.EmailField(max_length=50)
   Project_Manager_1 = models.ForeignKey(User, on_delete=models.CASCADE, related_name='User.Project_Manager_1_users+')
   Project_Manager_1_Mail_ID = models.EmailField(max_length=50)
   Project_Manager_2 = models.ForeignKey(User, on_delete=models.CASCADE, related_name='User.Project_Manager_2_users+', blank=True, null=True)
   Project_Manager_2_Mail_ID = models.EmailField(max_length=50, blank=True, null=True)
   Technician_1 = models.ForeignKey(User, on_delete=models.CASCADE, related_name='User.Technician_1_users+')
   Technician_1_Mail_ID = models.EmailField(max_length=50)
   Technician_2 = models.ForeignKey(User, on_delete=models.CASCADE, related_name='User.Technician_2_users+', blank=True, null=True)
   Technician_2_Mail_ID = models.EmailField(max_length=50, blank=True, null=True)
   Technician_3 = models.ForeignKey(User, on_delete=models.CASCADE, related_name='User.Technician_3_users+', blank=True, null=True)
   Technician_3_Mail_ID = models.EmailField(max_length=50, blank=True, null=True)
   Tester_1 = models.ForeignKey(User, on_delete=models.CASCADE, related_name='User.Tester_1_users+')
   Tester_1_Mail_ID = models.EmailField(max_length=50, default='Example@gmail.com')
   Additional_User_1 = models.ForeignKey(User, on_delete=models.CASCADE, related_name='User.Ad_1_users+', blank=True, null=True)
   Additional_User_1_Type = models.CharField(max_length=18, choices=STATUS_CHOICE, blank=True, null=True)
   Additional_User_1_Mail_ID = models.EmailField(max_length=50, blank=True, null=True)
   Additional_User_2 = models.ForeignKey(User, on_delete=models.CASCADE, related_name='User.Ad_1_users+', blank=True, null=True)
   Additional_User_2_Type = models.CharField(max_length=18, choices=STATUS_CHOICE, blank=True, null=True)
   Additional_User_2_Mail_ID = models.EmailField(max_length=50, blank=True, null=True)
   Additional_User_3 = models.ForeignKey(User, on_delete=models.CASCADE, related_name='User.Ad_1_users+', blank=True, null=True)
   Additional_User_3_Type = models.CharField(max_length=18, choices=STATUS_CHOICE, blank=True, null=True)
   Additional_User_3_Mail_ID = models.EmailField(max_length=50, blank=True, null=True)
   Status_of_the_project = models.CharField(max_length=18, choices=STATUS_CHOICE_1)
   Created = models.DateTimeField(auto_now_add=True, null=True, blank=True)
   Finish_Date = models.DateTimeField(null=True, blank=True)
   Supporting_Documents = models.FileField(null=True, blank=True)


   def __str__(self):
       return self.Project_Name

   class Meta:
       verbose_name_plural = "List Of Projects"

class Bug(models.Model):

   STATUS_CHOICE = (
       ('Unassigned', 'Unassigned'),
       ('Assigned', 'Assigned'),
       ('Testing', 'Testing'),
       ('Tested', 'tested'),
       ('Fixed', 'Fixed')
   )
   STATUS_CHOICE_1 = (
       ('Bug', 'Bug'),
       ('Issue', 'Issue'),
       ('Enhancement', 'Enhancement'),
       ('Not an issue or bug', 'Not an issue or bug'),
       ('Fixed', 'Fixed')
   )
   Project = models.ForeignKey(Project, on_delete=models.CASCADE)
   Issue_Title = models.CharField(max_length=50, blank=True, null=True)
   Situation_Type = models.CharField(max_length=25, choices=STATUS_CHOICE_1)
   Basic_Description = models.CharField(max_length=100)
   Detailed_Description = models.TextField(default='The Description, here.')
   Status = models.CharField(max_length=18, choices=STATUS_CHOICE)
   Assigned_to = models.ForeignKey(User, on_delete=models.CASCADE)
   Assigned_to_Mail_ID = models.EmailField(max_length=50, blank=True, null=True)
   Admin_Mail_ID = models.EmailField(max_length=50, blank=True, null=True)
   Reported_by = models.CharField(max_length=50, blank=True, null=True)
   Reporters_Mail_ID = models.EmailField(max_length=50, blank=True, null=True)
   Reported_Date = models.DateTimeField(null=True, blank=True)
   Created = models.DateTimeField(auto_now_add=True, null=True, blank=True)
   Updated = models.DateTimeField(auto_now=True, null=True, blank=True)
   Deadline_Date = models.DateTimeField(null=True, blank=True)
   Supporting_Documents_By_Reporter = models.FileField(null=True, blank=True)
   Project_Managers_Comment = models.TextField(default='The Description, here.')
   Supporting_Documents_by_Project_Manager = models.FileField(null=True, blank=True)
   Technicians_Comment = models.TextField(default='The Description, here.')
   Supporting_Documents_by_Technician = models.FileField(null=True, blank=True)
   Testers_Comment = models.TextField(default='The Description, here.')
   Supporting_Documents_by_Tester = models.FileField(null=True, blank=True)

   def __str__(self):
       return self.Project + ' (' + self.Situation_Type + ') ' + ' [' + self.Status + '] '

这是我的def send_mail(admin,ass): email=EmailMessage('Changes made to Task','Changes have been made to one of your Task reports and we hereby request you to have a look at it at the earliest.', to=[admin,ass]) email.send()

中的代码

admin.py

）

Answer 1

self.Project（实际上是将此类属性命名为project，而不是Project）是Project对象。

现在您写：

    self.Project + '('

（也有一些额外的补充，但此处与它们无关，至少不直接相关）。

因此，这意味着您希望将Project实例和str ing实例一起添加。但是由于您没有告诉Python如何做到这一点（通过重写__add__函数），因此无法做到这一点，但是我认为您还是不想这样做。

您可能想做的是，首先将self.Project转换为其str ing表示形式。我们可以使用字符串格式来做到这一点：

def __str__(self):
   return '{} ({})  [{}]'.format(self.Project, self.Situation_Type, self.Status)

此处，参数将自动转换为其文本对应的内容。此外，这也是一种产生字符串的 neater 方法。在原始代码中，可能很难找出)和[之间有两个空格，在这里我们可以立即看到（也许您想更改它）。

Django：类“ Project”未定义“ _add_”，因此无法在其实例上使用“ +”运算符

1 个答案: