CODEWITHSUNDEEP
pythonfastapipydantic
user787267
user787267

Reputation: 3010

Required field with sensible default

Consider the following

from pydantic import BaseModel, Field
class Model(BaseModel):
    required: str

This will make required a required field for Model, however, in the FastAPI autogenerated Swagger docs it will have an example value of "string".

How can I make a required field with a sensible default? If I make a model like

from pydantic import BaseModel, Field
class Model(BaseModel):
    required: str = 'Sensible default'

Then the field required is no longer required, but it shows up with a sensible default in the docs. Is there an easy workaround for this?

Upvotes: 2

Views: 1141

Answers (2)

Kendz2992
Kendz2992

Reputation: 41

You can use Field() to set up those options and check.

from pydantic import BaseModel, Field
class Model(BaseModel):
    something: str # required, shows "string"
    something: str = None # not required, shows "string"
    something: str = Field(..., example="this is the default display") # required, shows example
    something: str = Field(None, example="Foobar") #not required, show example

There are a multitude of different parameters that Field() can validate against.

Upvotes: 4

Hedde van der Heide
Hedde van der Heide

Reputation: 22459

I haven't looked into why the (pydantic) model representation within the openapi version that ships with FastAPI leaves the asterisk out, but the field is definitely still required (try putting a null value, or anything other than string). This might just be an UI inconsistency.

Upvotes: 2

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