Django查询根据属性获取常用项

I have a model as follows:

我有一个模型如下：

class Item(models.Model):
    VENDOR_CHOICES = (
        ('a', 'A'),
        ('b', 'B')
    )

    vendor = models.CharField(max_length=16, choices=VENDOR_CHOICES)
    name = models.CharField(max_length=255)
    price = models.DecimalField(max_digits=6, decimal_places=2)
class