Rust

Updated Nov 4, 2026

Installation

cargo add cardealer serde_json

Validation and consumption

The Rust library reads and validates a dataset; it does not write one.

use cardealer::Dataset;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let value: serde_json::Value = serde_json::from_str(&std::fs::read_to_string("dataset.json")?)?;
    let dataset = Dataset::from_value(value)?;
    println!("{} resources", dataset.resources.len());
    Ok(())
}

Resources

Dataset::resources is a Vec<CardealerResource>, an enum with one variant per table; each resource keeps its Fairspec fields in base and its typed rows in data:

use cardealer::{CardealerResource, Dataset};

fn count_cars(dataset: &Dataset) -> usize {
    dataset
        .resources
        .iter()
        .map(|resource| match resource {
            CardealerResource::Car(cars) => cars.data.len(),
            _ => 0,
        })
        .sum()
}

Rows

Dealer, Facility and Car validate on their own with from_value, and unlike the dataset they also implement Serialize, so rows can be written back out with serde_json:

use cardealer::Car;
use serde_json::json;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let car = Car::from_value(json!({
        "title": "BMW 3 Series 320d",
        "url": "https://www.premiumauto.com/cars/bmw-320d",
        "price": 32500,
        "currency": "USD",
        "mileage": 41000,
        "brand": "BMW",
        "model": "3 Series",
        "version": "320d",
        "fuel": "diesel",
        "gearbox": "auto",
        "category": "saloon",
        "color": "black",
        "door": "fourfive"
    }))?;
    println!("{}", serde_json::to_string(&car)?);
    Ok(())
}

from_value returns cardealer::Error: Error::Parse wraps the serde_json::Error for a missing column, a wrong type or an unknown enumeration value, and Error::Constraint names a broken rule such as a negative price or a wrong $schema.

Rust

Installation

Validation and consumption

Resources

Rows

Errors