ValidationError when using pydantic Field

Question

I run these codes by defining two classes, Blackboard and Table, based on BaseModel. The I defined another class which takes two attributes: bloackboard, defined to be a Blackboard; tables, defined to be a list of Table class objects.

from typing import List
from pydantic import BaseModel, Field


class Blackboard(BaseModel):
    size = 4000
    color: str = Field(..., alias='yanse',
                       description='the color of the blackboard, you can choose green or black.')


class Table(BaseModel):
    position: str


class ClassRoom(BaseModel):
    blackboard: Blackboard
    tables: List[Table]


m = ClassRoom(
    blackboard={'color': 'green'},
    tables=[{'position': 'first row, left 1'}, {'position': 'first row, left 2'}]
)

I got an error :

File "pydantic\main.py", line 342, in pydantic.main.BaseModel.__init__
pydantic.error_wrappers.ValidationError: 1 validation error for ClassRoom
blackboard -> yanse
  field required (type=value_error.missing)

I want to know how could I correctly use Field class.

Thanks

I expect to have no error.

You gave it an alias, so you should use the alias.

JarroVGIT
– JarroVGIT

2022-12-28 08:31:37 +00:00
Commented Dec 28, 2022 at 8:31 — JarroVGIT
– JarroVGIT, Commented Dec 28, 2022 at 8:31
Thank you. After using the alias, the problem is solved!

Tangming Li
– Tangming Li

2022-12-28 08:33:41 +00:00
Commented Dec 28, 2022 at 8:33 — Tangming Li
– Tangming Li, Commented Dec 28, 2022 at 8:33

Kiarash Fazli · Accepted Answer · 2022-12-28 12:12:55Z

2

You are using an alias for the color field in your schema and filling your data with python dictionaries.

in this case, you should replace:

blackboard={'color': 'green'}

with:

blackboard={'yanse': 'green'}

The color field is used when you have a python schema object, not in dictionaries.

answered Dec 28, 2022 at 12:12

Kiarash Fazli

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Comments

farch · Accepted Answer · 2023-01-05 20:03:46Z

0

In case you wanted to populate your Blackboard model using color, you can activate allow_population_by_field_name option in the Blackboard config options as follow:

class Blackboard(BaseModel):
    size = 4000
    color: str = Field(..., alias='yanse',
                       description='the color of the blackboard,
                        you can choose green or black.')

    class Config:
          allow_population_by_field_name = True

answered Jan 5, 2023 at 20:03

farch

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