65 releases (15 breaking)

new 0.16.1 May 20, 2024
0.15.1 May 5, 2024
0.14.2 Mar 7, 2024
0.12.8 Dec 4, 2023
0.11.0 Jul 3, 2023

#925 in Procedural macros

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2,352 downloads per month
Used in 16 crates (via schematic)

MIT license

2.5K SLoC


Schematic is a library that provides:

  • A layered serde-driven configuration system with support for merge strategies, validation rules, environment variables, and more!
  • A schema modeling system that can be used to generate TypeScript types, JSON schemas, and more!

Both of these features can be used independently or together.

cargo add schematic

Get started: https://moonrepo.github.io/schematic


  • Supports JSON, TOML, and YAML based configs via serde.
  • Load sources from the file system or secure URLs.
  • Source layering that merge into a final configuration.
  • Extend additional files through an annotated setting.
  • Field-level merge strategies with built-in merge functions.
  • Aggregated validation with built-in validate functions (provided by garde).
  • Environment variable parsing and overrides.
  • Beautiful parsing and validation errors (powered by miette).
  • Generates schemas that can be rendered to TypeScript types, JSON schemas, and more!

Define a struct or enum and derive the Config trait.

use schematic::Config;

struct AppConfig {
	#[setting(default = 3000, env = "PORT")]
	port: usize,

	#[setting(default = true)]
	secure: bool,

	#[setting(default = vec!["localhost".into()])]
	allowed_hosts: Vec<String>,

Then load, parse, merge, and validate the configuration from one or many sources. A source is either a file path, secure URL, or code block.

use schematic::{ConfigLoader, Format};

let result = ConfigLoader::<AppConfig>::new()
	.code("secure: false", Format::Yaml)?



Define a struct or enum and derive or implement the Schematic trait.

use schematic::Schematic;

struct Task {
	command: String,
	args: Vec<String>,
	env: HashMap<String, String>,

Then generate output in multiple formats, like JSON schemas or TypeScript types, using the schema type information.

use schematic::schema::{SchemaGenerator, TypeScriptRenderer};

let mut generator = SchemaGenerator::default();
generator.generate(output_dir.join("types.ts"), TypeScriptRenderer::default())?;


~34K SLoC