Pydantic："NoneType"对象不可下标(type=type_error)

Question

我使用Pydantic库获得了以下模型结构。我创建了一些类，其中一个类包含另一个类的项列表，所以问题是我不能使用以下类解析json：

class FileTypeEnum(str, Enum):
file = 'FILE'
folder = 'FOLDER'

class ImportInModel(BaseModel):
id: constr(min_length=1)
url: constr(max_length=255) = None
parentId: str | None = None
size: PositiveInt | None = None
type: FileTypeEnum
@root_validator
def check_url(cls, values: dict):
file_type = values['type']
file_url = values['url']
if file_type == FileTypeEnum.folder and file_url is not None:
raise ValueError(
f'{file_type}'s type file has {file_url} file url!'
)

@root_validator
def check_size(cls, values: dict):
file_type = values['type']
file_size = values['size']
if file_type == FileTypeEnum.file and file_size is None:
raise ValueError(
f'{file_type}'s type file has {file_size} file size!'
)

class ImportsInModel(BaseModel):
items: list[ImportInModel]
updateDate: datetime
class Config:
json_encoders = {
datetime: isoformat
}
json_loads = ujson.loads

@validator('items')
def check_parent(cls, v):
for item_1 in v:
for item_2 in v:
print(item_1.type, item_1.parentId, item_2.id, item_2.type)
assert item_1.type == FileTypeEnum.file 
and item_1.parentId == item_2.id  
and item_2.type == FileTypeEnum.folder

但后来我像一样使用它

try:
json_raw = '''{
"items": [
{
"id": "элемент_1_4",
"url": "/file/url1",
"parentId": "элемент_1_1",
"size": 234,
"type": "FILE"
}
],
"updateDate": "2022-05-28T21:12:01.000Z"
}
'''
ImportsInModel.parse_raw(json_raw)
# print(json_)
except ValidationError as e:
print(e)

它给了我错误：

ImportsInModel项的1个验证错误->0->__root__
'NoneType'对象不可下标(type=type_error(

我不知道出了什么问题，因为它实际上是文档的副本。

Answer 1

如果成功，则必须在验证后返回解析结果，即在ImportInModel中的两个root_validator的末尾添加return values。

例如，如果我运行以下代码，就会出现相应的错误：

if __name__ == '__main__':
try:
x_raw = ''' 
{     
"id": "элемент_1_4",
"url": "/file/url1",
"parentId": "элемент_1_1",
"size": 234,
"type": "FILE"
} 

'''
y = ImportInModel.parse_raw(x_raw)
except ValidationError as e:
print(e)

Traceback (most recent call last):
File "pydantic/main.py", line 344, in pydantic.main.BaseModel.__init__
TypeError: __dict__ must be set to a dictionary, not a 'NoneType'
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "/Users/will/PycharmProjects/pythonProject2/pydantic_1.py", line 90, in <module>
y = ImportInModel.parse_raw(x_raw)
File "pydantic/main.py", line 549, in pydantic.main.BaseModel.parse_raw
File "pydantic/main.py", line 526, in pydantic.main.BaseModel.parse_obj
File "pydantic/main.py", line 346, in pydantic.main.BaseModel.__init__
TypeError: Model values must be a dict; you may not have returned a dictionary from a root validator

至于ImportsInModel中的验证器，也许您应该检查代码的逻辑。您的代码想要断言item_1.parentId == item_2.id。但是，在您的测试用例中，item_1.parentId永远不会等于item_2.id，因为您的items列表中只有一个项目，即item_1 == item_2。

所以最后的片段是：

from datetime import datetime
from enum import Enum
import ujson
from pydantic.json import isoformat
from pydantic import BaseModel, constr, PositiveInt, root_validator, validator, ValidationError

class FileTypeEnum(Enum):
file = 'FILE'
folder = 'FOLDER'

class ImportInModel(BaseModel):
id: constr(min_length=1)
url: constr(max_length=255) = None
parentId: str | None = None
size: PositiveInt | None = None
type: FileTypeEnum
@root_validator
def check_url(cls, values: dict):
file_type = values['type']
file_url = values['url']
if file_type == FileTypeEnum.folder and file_url is not None:
raise ValueError(
f'{file_type}'s type file has {file_url} file url!'
)
return values
@root_validator
def check_size(cls, values: dict):
file_type = values['type']
file_size = values['size']
if file_type == FileTypeEnum.file and file_size is None:
raise ValueError(
f'{file_type}'s type file has {file_size} file size!'
)
return values

class ImportsInModel(BaseModel):
items: list[ImportInModel]
updateDate: datetime
class Config:
json_encoders = {
datetime: isoformat
}
json_loads = ujson.loads
@validator('items')
def check_parent(cls, v):
for item_1 in v:
for item_2 in v:
print(item_1.type, item_1.parentId, item_2.id, item_2.type)
assert item_1.type == FileTypeEnum.file 
and item_1.parentId == item_2.id 
and item_2.type == FileTypeEnum.folder

if __name__ == '__main__':
try:
json_raw = '''{
"items": [
{
"id": "элемент_1_4",
"url": "/file/url1",
"parentId": "элемент_1_1",
"size": 234,
"type": "FILE"
}
],
"updateDate": "2022-05-28T21:12:01.000Z"
}
'''
x_raw = ''' 
{     
"id": "элемент_1_4",
"url": "/file/url1",
"parentId": "элемент_1_1",
"size": 234,
"type": "FILE"
} 

'''
y = ImportInModel.parse_raw(x_raw)
z = ImportsInModel.parse_raw(json_raw)
print(y, z)
except ValidationError as e:
print(e)