vld-clap

Clap integration for the vld validation library.

Validate CLI arguments after clap has parsed them — email format, URL, ranges, string lengths, regex patterns, and everything else vld supports. Validation rules go directly on the Cli struct via #[derive(Validate)].

Why

Clap handles argument parsing (types, defaults, required/optional), but doesn't validate semantic constraints like "must be a valid email" or "port must be 1–65535". vld-clap fills that gap — no separate schema struct needed.

Installation

[dependencies]
vld-clap = "0.1"
vld = { version = "0.1", features = ["derive"] }
clap = { version = "4", features = ["derive"] }
serde = { version = "1", features = ["derive"] }

Quick Start

use clap::Parser;
use vld::Validate;
use vld_clap::prelude::*;

#[derive(Parser, Debug, serde::Serialize, Validate)]
#[command(name = "myapp")]
struct Cli {
    #[arg(long)]
    #[vld(vld::string().email())]
    email: String,

    #[arg(long, default_value_t = 8080)]
    #[vld(vld::number().int().min(1).max(65535))]
    port: i64,

    #[arg(long)]
    #[vld(vld::string().min(2).max(50))]
    name: String,
}

fn main() {
    let cli = Cli::parse();
    validate_or_exit(&cli);
    println!("email={}, port={}", cli.email, cli.port);
}

API

Function	Description
`validate(args)`	Validate a struct with `#[derive(Validate)]` + `Serialize`
`validate_or_exit(args)`	Validate; print error & exit(2) on failure
`validate_with_schema::<S, T>(args)`	Validate `T: Serialize` against a separate schema `S`
`validate_json::<S>(json)`	Validate raw JSON

Error Output

Invalid arguments:
       --email: Invalid email address
       --name: String must be at least 2 characters
       --port: Number must be at most 65535

Examples

# Valid
cargo run -p vld-clap --example clap_basic -- \
  --email alice@example.com --name Alice --port 3000 --workers 8

# Invalid (exits with code 2)
cargo run -p vld-clap --example clap_basic -- \
  --email bad --name X --port 99999 --workers 0

License

MIT

vld-clap 0.3.0