Pydantic's Data Coercion: From Raw Data to Python Types
Pydantic automatically converts raw data, like strings from a JSON request, into the Python types you declare. It's how FastAPI turns a JSON body into a typed Python object.
Pydantic automatically coerces raw input data, like strings from a JSON request, into the specific Python types you declare in your models. This is the magic behind FastAPI, where a JSON payload `{"id": "123"}` is seamlessly converted into a model field `id: int = 123`. The footgun: default coercion is very permissive. '1', 1, and 'true' can all become `True`. To prevent this, use Pydantic's `Strict` types (`StrictInt`, `StrictBool`) which forbid coercion.
Read the original → pydantic.dev
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