Can I initialize a pydantic model using the "unaliased" attribute name?

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I'm working with an API where the schema for creating a group is effectively:

class Group(BaseModel):
  identifier: str

I was hoping I could do this instead:

class Group(BaseModel):
  groupname: str = Field(..., alias='identifier')

But with that configuration it's not possible to set the attribute value using the name groupname. That is, running this fails with a field required error:

>>> g = Group(groupname='foo')
pydantic.error_wrappers.ValidationError: 1 validation error for Group
identifier
  field required (type=value_error.missing)

Is it is possible to use either the alias or the actual attribute name to set the attribute value? I was hoping that these two would be equivalent:

>>> Group(identifier='foo')
>>> Group(groupname='foo')
pydantic python
1 Answers

Maybe you are looking for the allow_population_by_field_name config option:

whether an aliased field may be populated by its name as given by the model attribute, as well as the alias (default: False)

from pydantic import BaseModel, Field


class Group(BaseModel):
    groupname: str = Field(..., alias='identifier')

    class Config:
        allow_population_by_field_name = True


print(repr(Group(identifier='foo')))
print(repr(Group(groupname='bar')))

Output:

Group(groupname='foo')
Group(groupname='bar')
user_27381510
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