[Python] parse json file to Pydantic model

I created a model of Pydantic. But it does not convert and outputs an error Please tell me,what is wrong.

classDTO:

from pydantic import BaseModel,Field
from typing import List,Dict
from datetime import date

class OurBaseModel(BaseModel):
pass
#class Config:
#orm_mode = True

class SessionSubjectDTO(OurBaseModel):
edu_year: int
semester_type: str

class MarkDTO(OurBaseModel):
semester_number: int
subject_name: str
control_type: str
mark: str # or int
session_subject: SessionSubjectDTO #= Field(None, alias="SessionSubjectDTO")

class MarksDTO(OurBaseModel):
__root__: List[MarkDTO]

class AttestationDTO(BaseModel):
subject_name: str
value: int
attestation_start_date: date

class AttestationsDTO(OurBaseModel):
__root__: List[AttestationDTO]

class DebtDTO(OurBaseModel):
semester_number: int
subject_name: str
control_type: str
session_subject: SessionSubjectDTO #= Field(None, alias="SessionSubjectDTO")

class DebtsDTO(OurBaseModel):
__root__: List[DebtDTO]

class SkipDTO(OurBaseModel):
valid: int
no_valid: int
attestation_start_date: date

class SkipsDTO(OurBaseModel):
__root__: List[SkipDTO]

class StudentDTO(OurBaseModel):
uid: str
marks: MarksDTO
attestations: AttestationsDTO
debts: DebtsDTO
skips: SkipsDTO

class StudentsDTO(OurBaseModel):
__root__: List[StudentDTO]


example.json:

[
{
"uid": "61c689ac-98a1-11e9-8198-4ccc6a2d123b",
"marks": [
{
"semester_number": 1,
"subject_name": "454",
"control_type": "5",
"mark": "3.",
"date": "2019-12-27",
"session_subject": {
"id": 4228,
"edu_year": 2019,
"semester_type": "1"
}
}
],
"attestations": [
{
"subject_name": "133",
"value": 2,
"attestation_start_date": "2019-10-07",
"attestation_end_date": "2019-10-12"
}
],
"debts": [
{
"semester_number": 4,
"subject_name": "323",
"control_type": "12",
"session_subject": {
"id": 22856,
"edu_year": 2020,
"semester_type": "20"
}
}
],
"skips": [
{
"valid": null,
"no_valid": null,
"attestation_start_date": "2020-03-09",
"attestation_end_date": "2020-03-14"
}
]
}
]


main.py:

students = pydantic.parse_file_as(path='192.json', type_=classDTO.StudentsDTO)


Errors:

Traceback (most recent call last):
File "main.py", line 73, in <module>
students = pydantic.parse_file_as(path='192.json', type_=classDTO.StudentsDTO)
File "pydantic\tools.py", line 60, in pydantic.tools.parse_file_as
File "pydantic\tools.py", line 38, in pydantic.tools.parse_obj_as
File "pydantic\main.py", line 331, in pydantic.main.BaseModel.__init__
pydantic.error_wrappers.ValidationError: 424 validation errors for ParsingModel[StudentsDTO]
__root__ -> __root__ -> 0 -> attestations -> __root__ -> 18 -> value
none is not an allowed value (type=type_error.none.not_allowed)
__root__ -> __root__ -> 0 -> attestations -> __root__ -> 19 -> value
none is not an allowed value (type=type_error.none.not_allowed)
__root__ -> __root__ -> 0 -> attestations -> __root__ -> 20 -> value
none is not an allowed value (type=type_error.none.not_allowed)
...
__root__ -> __root__ -> 16 -> skips -> __root__ -> 1 -> no_valid
none is not an allowed value (type=type_error.none.not_allowed)


I tried to solve the problem with Custom Root Types:

Pydantic models can be defined with a custom root type by declaring the field. __root__

The root type can be any type supported by pydantic, and is specified by the type hint on the __root__ field. The root value can be passed to the model __init__ via the __root__ keyword argument, or as the first and only argument to parse_obj.
​

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