Concerto Validator RS

A Rust library that validates Accord Project Concerto data models in their JSON AST (Abstract Syntax Tree) format.

Overview

This validator implements the core functionality of the JavaScript validateMetaModel function by:

1. Loading the raw Concerto Metamodel JSON directly as the validation schema
2. Using a ModelManager that works with raw JSON instead of hardcoded Rust structs. Except for a few structs needed to replicate some functionality of the introspect classes.

Features

• ✅ Auto-Updating Metamodel: Build script automatically checks and updates the metamodel from the official repository
• ✅ Dynamic Metamodel Loading: Loads metamodel from raw JSON instead of hardcoded structures
• ✅ Complete Metamodel Support: Validates against the full Concerto metamodel specification
• ✅ Structural Validation: Ensures JSON structure matches expected Concerto AST format
• ✅ Type Validation: Validates property types, arrays, optionality, and nested objects
• ✅ Error Reporting: Provides detailed error messages for debugging
• ✅ Self-Validation: Can validate the Concerto metamodel itself
• ✅ Performance: Fast validation using native Rust performance
• ✅ Command Line Interface: Extensible CLI tool for validating JSON files

Installation

Currently the library is in early development phase, the package is not published to crates.io yet.

Automatic Metamodel Updates

The library includes a build script that automatically ensures you're always using the latest version of the Concerto Metamodel as the source of truth.

How it works:

• On every build, the script checks the local metamodel.json against the official version
• If the local file is missing, outdated, or corrupted, it automatically downloads the latest version
• The comparison uses SHA256 hashing of normalized JSON to detect changes
• Build warnings inform you when updates occur

Features:

• ✅ Automatic detection of metamodel updates
• ✅ Graceful fallback to local version if network is unavailable
• ✅ JSON validation to ensure downloaded content is valid
• ✅ Build-time integration with no runtime overhead

This ensures that your validator is always using the official, up-to-date metamodel definition without manual intervention.

Usage

Command Line Interface

The project includes a command-line tool for validating Concerto model JSON files:

Building the CLI

cargo build

Basic Validation

# Validate a single file
./target/debug/concerto-validator validate --input model.json

# Validate multiple files
./target/debug/concerto-validator validate --input model1.json --input model2.json --input model3.json

# Stop at the first error (fail-early mode)
./target/debug/concerto-validator validate --input model1.json --input model2.json --fail-early

CLI Help

# General help
./target/debug/concerto-validator --help

# Help for the validate command
./target/debug/concerto-validator validate --help

# Show version
./target/debug/concerto-validator --version

Library Usage

Basic Usage

use concerto_validator_rs::validate_metamodel;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let model_json = r#"{
        "$class": "[email protected]",
        "namespace": "[email protected]",
        "imports": [],
        "declarations": [
            {
                "$class": "[email protected]",
                "name": "Person",
                "isAbstract": false,
                "properties": [
                    {
                        "$class": "[email protected]",
                        "name": "firstName",
                        "isArray": false,
                        "isOptional": false
                    }
                ]
            }
        ]
    }"#;

    match validate_metamodel(model_json) {
        Ok(()) => println!("✅ Model is valid!"),
        Err(e) => println!("❌ Validation error: {}", e),
    }

    Ok(())
}

Related Projects

• Accord Project Concerto - The original JavaScript implementation
• Concerto Metamodel - The metamodel definition used for validation

License

Accord Project source code files are made available under the Apache License, Version 2.0. Accord Project documentation files are made available under the Creative Commons Attribution 4.0 International License (CC-BY-4.0).

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