ValidationDBProviderclass

Database provider that validates data flowing to and from an asynchronous source provider.

• Wraps a source provider (which may have any type, because validation guarantees the type) and runs every value through the relevant Collection schema before writing and after reading.
• Written data is validated against the collection's data schema; read data is validated against the item schema, so trusted, correctly-typed values reach the rest of the app.
• Validation failures here are program-state errors, so they throw a typed ValueError rather than a raw validation string.

A wrapping provider that validates data against the collection schema. ValidationDBProvider validates data on the way in (writes) and on the way out (reads) — so bad data never reaches the backend, and corrupt data from the backend surfaces as a ValueError rather than propagating silently.

Place it between the cache and the backend so cached data is always known-good.

Usage

import { ValidationDBProvider, MemoryDBProvider } from "shelving/db";

const provider = new ValidationDBProvider(new MemoryDBProvider());

// Validated against the POSTS schema before writing.
await provider.addItem(POSTS, { title: "Hello", body: "…", published: false });

// If the backend ever returns data that fails the schema, this throws ValueError.
const post = await provider.getItem(POSTS, "abc");