Python reference

Pydantic & core
cheat sheet.

Pydantic models, validation, serialization, settings, and custom types, with direct pydantic-core examples.

44 topics60 code examplesUpdated 22 Oct 2026

How Pydantic & core fits together

01Describe the shapePython types and field rules define accepted input.

02Validate the boundaryPydantic builds and runs a compiled core schema.

03Use typed valuesYour application works with checked Python objects.

04Control the outputSerialization defines the public data you expose.

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5 chapters · 44 topics

CHAPTER 01 / 05

Define Pydantic models with typed fields, defaults, aliases, nested data, and discriminated unions. Handle strict input and partial updates.

12 topics

CHAPTER 02 / 05

Write Pydantic field and model validators, custom serializers, and computed fields. Handle validation errors and keep sensitive fields out of output.

9 topics

CHAPTER 03 / 05

Use Pydantic TypeAdapter, RootModel, generics, recursive models, and ORM attributes. Generate JSON Schema for input and output contracts.

7 topics

CHAPTER 04 / 05

Configure pydantic-settings with environment variables and nested settings. Validate email addresses and use additional domain-specific types.

3 topics

CHAPTER 05 / 05

Build Pydantic custom types and pydantic-core schemas. Python examples cover SchemaValidator, SchemaSerializer, context, unions, and tests.

13 topics