ManyToMany 字段查詢返回空集但不為空

Question

我有一個多對多字段，當查詢時返回一個空的 QuerySet 但絕對不是空的。 我可以從管理頁面看到這一點。

我可以在管理員中看到空缺（id = 1）中有一個應用程序object。 另外，當我查詢應用程序的作業時，它返回空缺（id = 1）。

我在下面包含了我的 shell 腳本。

模型.py

class Vacancy(models.Model):
    CATEGORY_CHOICES = [
        ('ADMINISTRATION', 'Administration'),
        ('CONSULTING', 'Consulting'),
        ('ENGINEERING', 'Engineering'),
        ('FINANCE', 'Finance'),
        ('RETAIL', 'Retail'),
        ('SALES', 'Sales'),
    ]
    employer = models.ForeignKey('Employer', on_delete=models.CASCADE)
    job_title = models.CharField(max_length=35, default=None)
    main_duties = models.TextField(default=None, validators=[
        MinLengthValidator(650),
        MaxLengthValidator(2000)
    ])
    person_spec = models.TextField(default=None, validators=[
        MinLengthValidator(650),
        MaxLengthValidator(2000)
    ])
    salary = models.PositiveIntegerField(default=None, validators=[
        MinValueValidator(20000), 
        MaxValueValidator(99000)
    ])
    city = models.CharField(choices=CITY_CHOICES, max_length=11, default=None)
    category = models.CharField(choices=CATEGORY_CHOICES, max_length=15, default=None)
    max_applications = models.PositiveSmallIntegerField(blank=True, null=True)
    deadline = models.DateField(blank=True, null=True)
    applications = models.ManyToManyField('Application', blank=True)
    active = models.BooleanField(default=True)

    class Meta:
        verbose_name_plural = 'vacancies'



class Application(models.Model):
    STAGES = [
        ('pre-selection', 'PRE-SELECTION'),
        ('shortlisted', 'SHORTLISTED'),
        ('rejected pre-interview', 'REJECTED PRE-INTERVIEW'),
        ('rejected post-interview', 'REJECTED POST-INTERVIEW'),
        ('successful', 'SUCCESSFUL')
    ]
    candidate = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
    job = models.ForeignKey('Vacancy', on_delete=models.CASCADE)
    cv = models.CharField(max_length=35, default=None)
    cover_letter = models.TextField(default=None, validators=[
        MinLengthValidator(0),
        MaxLengthValidator(2000)
    ])
    submitted = models.DateTimeField(auto_now_add=True)
    stage = models.CharField(choices=STAGES, max_length=25, default='pre-selection')

管理.py shell

>>> from recruit.models import *
>>> RA = Vacancy.objects.get(id=1)
>>> RA
<Vacancy: 1 Research Administrator>
>>> RA.applications.all()
<QuerySet []>
>>> App = Application.objects.get(id=1)
>>> App.job.id
1
>>> App.job
<Vacancy: 1 Research Administrator>
>>>

關於為什么這不起作用的任何想法？

Answer 1

解決了：

class Vacancy(models.Model):
    applications = models.ManyToManyField('Application', symmetrical=False, blank=True)

缺少應用程序字段上的symmetrical=False屬性！