我需要在django-mptt模型上使用bulk_create
,但我得到一个错误:
django.db.utils.IntegrityError: null value in column "lft" violates not-null constraint DETAIL: Failing row contains (2, Magic, null, null, null, null, null, null, 1).
我如何批量创建django mptt模型而无需硬编码lft
、rght
和tree_id
?
型号。py:
from mptt.models import MPTTModel, TreeForeignKey
class Category(MPTTModel):
parent = TreeForeignKey('self', on_delete=models.CASCADE, blank=True,
null=True, related_name='children',
)
name = models.CharField(max_length=255)
tcgplayer_category = models.ForeignKey('tcgplayer.TcgCategory', on_delete=models.PROTECT,
blank=True, null=True)
class Meta:
unique_together = (
('parent', 'name'),
)
def __str__(self):
return self.name
class TcgCategory(models.Model):
id = models.PositiveSmallIntegerField(primary_key=True)
name = models.CharField(max_length=255)
class CategoryGroup(models.Model):
id = models.IntegerField(primary_key=True)
category = models.ForeignKey('tcgplayer.TcgCategory', on_delete=models.CASCADE)
fixtures/category.json:
[{
"model": "tcgplayer.tcgcategory",
"pk": 1,
"fields": {
"name": "Magic",
}
}, {
"model": "tcgplayer.categorygroup",
"pk": 1,
"fields": {
"category": 1,
"name": "10th Edition",
}
}, {
"model": "tcgplayer.categorygroup",
"pk": 2,
"fields": {
"category": 1,
"name": "7th Edition",
}
}]
任务。py:
def convert_categories(category_ids):
root_categories = TcgCategory.objects.filter(id__in=category_ids)
category_parents = Category.objects.bulk_create([ # error is thrown here
Category(
tcgplayer_category_id=model['id'],
name=model['name'],
)
for model in root_categories.values('id', 'name')
])
for parent in category_parents:
category_groups = CategoryGroup.objects.filter(category_id=parent.tcgplayer_category_id)
category_models.extend([
Category(
tcgplayer_category_id=model['id'],
name=model['name'],
parent=parent,
)
for model in category_groups.values('id', 'name')
])
Category.objects.bulk_create(category_models)
延迟回复,但硬编码
lft
、rght
和tree_id
并没有错。这就是在创建模型后添加MPTTModel类时的实际情况,只要在创建后运行rebuild
不过,您可能需要将模型稍微调整为add some kind of ordering
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