pydantic.error_wrappers.ValidationError: 1 validation error for B

Question

When I try to parse JSON object with Pydantic, my IDE returns error...

Code:

from pydantic import BaseModel, Field
class A(BaseModel):
    a: str = Field(None, alias="А")
class B(BaseModel):
    b: dict[str, A] = Field(None, alias="Б")
j = {
    "Б": {
        "А": "Значение"
    }
}
obj=B.parse_obj(j)

... and error text:

File "pydantic/main.py", line 572, in pydantic.main.BaseModel.parse_obj
  File "pydantic/main.py", line 400, in pydantic.main.BaseModel.__init__
pydantic.error_wrappers.ValidationError: 1 validation error for B
Б -> А
  value is not a valid dict (type=type_error.dict)

please answer why this is happening

Solution

Oh, it was so simple... instead of using a dict type, just use the model A, which already matches the subobject.

from pydantic import BaseModel, Field
class A(BaseModel):
    a: str = Field(None, alias="А")
class B(BaseModel):
    b: A = Field(None, alias="Б")
j = {
    "Б": {
        "А": "Значение"
    }
}
obj = B.parse_obj(j)
print(obj.json())