Python Pydantic use multiple field alias

Question

Is there any way to use multiple field alias without using root_validator?

My current code is this:

class GetInfo(BaseModel):
    name: str = Field(alias='name1')
    name2: str = Field(alias='name2')
    
    @root_validator
    def format_name(cls, values):
        if values['name'] is None:
            if values['name2'] is not None:
                values['name'] = values['name2']
            return values
        return None

The name1 field is sometimes empty while the name2 field is mostly not empty I wanted to use the name2 if the name1 is really empty.

Or can you suggest better way than what I did?

You mention "empty", but your code validates `None`. Are you confusing `""` with `None`? — Hernán Alarcón, Dec 13 '21 at 16:59
See this branch https://github.com/samuelcolvin/pydantic/issues/324 — Давид Шико, Jul 12 '22 at 07:09

Yaakov Bressler · Answer 1 · 2023-08-03T16:31:25.177

2

Pydantic V1:

Short answer, you are currently restricted to a single alias. (In other words, your field can have 2 "names".) If you want additional aliases, then you will need to employ your workaround.

Pydantic V2:

Pydantic V2 introduces "more powerful alias(es)":

class GetInfo(BaseModel):
    name: str = Field(validation_alias=AliasChoices('name1', 'name_1', 'name_one'))
    name2: str = Field(validation_alias=AliasChoices('name2', 'name_2', 'name_two'))


# The following will all be equal
assert all((
    GetInfo(name1="Sam", name2="Colvin"),
    GetInfo(name_1="Sam", name_2="Colvin"),
    GetInfo(name_one="Sam", name_two="Colvin"),
))

edited Aug 03 '23 at 16:31

answered Apr 05 '23 at 16:48

Yaakov Bressler

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it is not working, it seems that aliases parameter has a different behavior. any idea how to do that? – infinity911 Aug 03 '23 at 10:47
Fixed it, thanks for pointing it out @infinity911 – Yaakov Bressler Aug 03 '23 at 16:31
you just stole my answer. – infinity911 Aug 04 '23 at 07:57

score 1 · Answer 2 · answered Aug 03 '23 at 15:40

if anyone is wondering, here is a working solution with pydantic v2

import pydantic
print(pydantic.__version__ )  # 2.1.0 
from pydantic import BaseModel, Field, AliasChoices
class User(BaseModel):
    first_name: str = Field(validation_alias=AliasChoices('first_name', 'fname'))
print(User(first_name="Sam"))
print(User(fname="toto"))

Python Pydantic use multiple field alias

2 Answers2

Pydantic V1:

Pydantic V2: