How to use a reserved keyword in pydantic model

Question

I need to create a schema but it has a column called global, and when I try to write this, I got an error.

class User(BaseModel):

    id:int
    global:bool

I try to use another name, but gives another error when try to save in db.

Answer 1

It looks like you are using a pydantic module. You can't use the name global because it's a reserved keyword so you need to use this trick to convert it.

pydantic v1:

class User(BaseModel):
    id: int
    global_: bool

    class Config:
        fields = {
            'global_': 'global'
        }

or pydantic v1 & v2:

class User(BaseModel):
    id: int
    global_: bool = Field(..., alias='global')

To create a class you have to use a dictionary (because User(id=1, global=False) also throws an error):

user = User(id=1, global=False)

> Traceback (most recent call last):
> (...)
> File "<input>", line 1
>  User(id=1, global=False)
>             ^^^^^^
> SyntaxError: invalid syntax

user = User(**{'id': 1, 'global': False})

Set allow_population_by_field_name = True or populate_by_name=True in config to allow creating models using both global and global_ names (thanks @GooDeeJAY).

pydantic v1:

class User(BaseModel):
    id: int
    global_: bool = Field(..., alias='global')

    class Config:
        allow_population_by_field_name = True

pydantic v2:

class User(BaseModel):
    id: int
    global_: bool = Field(..., alias='global')
    model_config = ConfigDict(populate_by_name=True)


user1 = User(**{'id': 1, 'global': False})
user2 = User(id=1, global_=False)
assert user1 == user2

By default schema dump will not use aliased fields:

user.dict() # for pydantic v1
user.model_dump() # for pydantic v2
> {'id': 1, 'global_': False}

To get data in the correct schema use by_alias:

user.dict(by_alias=True) # for pydantic v1
user.model_dump(by_alias=True) # for pydantic v2
> {'id': 1, 'global': False}