CodeRef. Rust & Python
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Python reference library

Python
cheat sheets.

Web APIs, validation, data pipelines, databases, and tests. These references cover FastAPI, Pydantic, Polars, SQLAlchemy, and pytest.

5 Python guides

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Python

FastAPI

Python web APIs

Routes, request validation, dependencies, SQLAlchemy, authentication, and testing.

ValidationDependenciesAuth
8 chapters 28 topicsExplore
Python

Pydantic & core

Data validation and serialization

Models, validators, serialization, settings, custom types, and pydantic-core.

Models & validationSerializationpydantic-core
5 chapters 44 topicsExplore
Python

Polars

DataFrames and data pipelines

Expressions, joins, file formats, reporting, lazy queries, and streaming.

Expressions & joinsLazy queriesFile pipelines
7 chapters 50 topicsExplore
Python

SQLAlchemy

ORM queries and transactions

Models, queries, relationships, and transactions, with matching SQL examples.

QueriesRelationshipsAsyncIO
4 chapters 27 topicsExplore
Python

pytest

Python tests and fixtures

Assertions, fixtures, parametrization, mocks, async tests, and plugins.

FixturesMocksPlugins
4 chapters 26 topicsExplore
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Use FastAPI dependenciesShare request logic and resources through Depends.Validate Pydantic fieldsTransform input and check values with before and after validators.Join Polars DataFramesChoose join types and check duplicate-key cardinality.Parametrize pytest testsRun one test against several inputs and expected results.Avoid N+1 database queriesChoose eager loading for SQLAlchemy relationships.Clean a sales CSV with PolarsFollow a complete pipeline from messy input to a report.