Models and protocols

Small programs for validation, schemas, borrowed input, streaming JSON and native binary codecs.

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Validate a data contract

Source: crates/rydantic/examples/data_contract.rs

cargo run --locked -p rydantic --example data_contract

Normalizes a signup, prints four field errors for a second input and generates an input schema. No optional feature flags are needed. Follow the first-model tutorial to build it in a standalone project.

Inspect a model and its schema

Source: crates/rydantic/examples/user.rs

cargo run --locked -p rydantic --example user

Prints a normalized user, structured errors and a schema report including local runtime rules. See validation and JSON Schema.

Dispatch a tagged tool call

Source: crates/rydantic/examples/tool_call.rs

cargo run --locked -p rydantic --example tool_call
cargo run --locked -p rydantic --example tool_call -- '{"kind":"ping"}'
cargo run --locked -p rydantic --example tool_call -- --schema

The default command searches a local text corpus; ping returns {"results":["pong"]}. The last command prints the input schema. Invalid arguments produce structured errors and exit status 2.

Borrow from input JSON

Source: crates/rydantic/examples/borrowed.rs

cargo run --locked -p rydantic --example borrowed

Checks borrowed strings, flattened fields and extra keys. Escaped strings use owned storage where decoding requires it. See borrowed models for lifetime requirements.

Process arrays and NDJSON

Source: crates/rydantic/examples/streaming.rs

cargo run --locked -p rydantic --example streaming

Visits a JSON array containing one invalid row, then processes newline-delimited JSON containing a malformed record. Prints row results and errors as it goes. This example parses input records; the AI streaming tutorial consumes model output.

Await a custom validator

Source: crates/rydantic/examples/asynchronous.rs

cargo run --locked -p rydantic --example asynchronous

Accepts Alice and rejects the reserved name taken through an async field check. The simulated availability check is local. Read asynchronous validation to connect an application check.

Parse dates and exact decimals

Source: crates/rydantic/examples/dates_decimal.rs

cargo run --locked -p rydantic --example dates_decimal --features chrono,decimal

Normalizes a timestamp and serializes an exact decimal string. Both optional features are required. See dates and decimals.

Generate a native Cap’n Proto codec

Source: crates/rydantic/examples/auto_capnp.rs

Install the official capnp compiler and make it available on PATH, then run:

cargo run --locked -p rydantic --example auto_capnp --features capnp

Derives bindings from model definitions, round-trips ordinary and packed messages, and prints the generated .capnp schema. See native Cap’n Proto for compiler setup and schema evolution.