Garde

A Rust validation library

use garde::{Validate, Valid};
use serde::Deserialize;

#[derive(Deserialize, Validate)]
struct User<'a> {
    #[garde(ascii, length(min=3, max=25))]
    username: &'a str,
    #[garde(length(min=15))]
    password: &'a str,
}

let user = serde_json::from_str::<User>(r#"
{
    "username": "lolcode",
    "password": "hunter2"
}
"#).unwrap();

println!("{}", user.validate(&()).unwrap_err());

Garde can also validate enums:

use garde::{Validate, Valid};
use serde::Deserialize;

#[derive(Deserialize, Validate)]
#[serde(rename_all="lowercase")]
enum Data {
    Struct {
        #[garde(range(min=-10, max=10))]
        field: i32,
    },
    Tuple(
        #[garde(rename="important", ascii)]
        String
    ),
}

let data = serde_json::from_str::<Vec<Data>>(r#"
[
    { "struct": { "field": 100 } },
    { "tuple": "test" }
]
"#).unwrap();

for item in &data {
    println!("{}", item.validate(&()).unwrap_err());
}

Available validation rules

name	format	validation	feature flag
ascii	`#[garde(ascii)]`	only contains ASCII	-
alphanumeric	`#[garde(alphanumeric)]`	only letters and digits	-
email	`#[garde(email)]`	an email according to the HTML5 spec[^1]	`email`
url	`#[garde(url)]`	a URL	`url`
ip	`#[garde(ip)]`	an IP address (either IPv4 or IPv6)	-
ipv4	`#[garde(ipv4)]`	an IPv4 address	-
ipv6	`#[garde(ipv6)]`	an IPv6 address	-
credit card	`#[garde(credit_card)]`	a credit card number	`credit-card`
phone number	`#[garde(phone_number)]`	a phone number	`phone-number`
length	`#[garde(length(min=<usize>, max=<usize>)]`	a dynamically-sized value with size in the range `min..=max`	-
range	`#[garde(range(min=<expr>, max=<expr>))]`	a number in the range `min..=max`	-
contains	`#[garde(contains(<string>))]`	a string-like value containing a substring	-
prefix	`#[garde(prefix(<string>))]`	a string-like value prefixed by some string	-
suffix	`#[garde(suffix(<string>))]`	a string-like value suffixed by some string	-
pattern	`#[garde(pattern(<regex>))]`	a string-like value matching some regular expression	`pattern`
dive	`#[garde(dive)]`	nested validation, calls `validate` on the value	-
custom	`#[garde(custom(<function or closure>))]`	a custom validator	-

Additional notes:

For length and range, either min or max may be omitted, but not both.
length and range use an inclusive upper bound (min..=max).
length uses .chars().count() for UTF-8 strings instead of .len().
For contains, prefix, and suffix, the pattern must be a string literal, because the Pattern API is currently unstable.
Nested validation using dive may not be combined with any other rule.

Feature flags

name	description	extra dependencies
`derive`	Enables the usage of the `derive(Validate)` macro	`garde_derive`
`url`	Validation of URLs via the `url` crate.	`url`
`email`	Validation of emails according to HTML5	`regex`, `once_cell`
`email-idna`	Support for Internationalizing Domain Names for Applications in email addresses	`idna`
`pattern`	Validation using regular expressions via the `regex` crate	`regex`, `once_cell`
`credit-card`	Validation of credit card numbers via the `card-validate` crate	`card-validate`
`phone-number`	Validation of phone numbers via the `phonenumber` crate	`phonenumber`
`nightly-error-messages`	Enables usage of `rustc_on_unimplemented` for better error messages. This is an unstable feature and requires a nightly compiler.	-

Why `Garde`?

Garde means guard in French. I am not French, nor do I speak the language, but guard was taken, and this is close enough :).

License

Licensed under either of

Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Acknowledgements

This crate is heavily inspired by the validator crate. It is essentially a full rewrite of validator. The creation of this crate was prompted by this comment and a few others talking about a potential rewrite.

[^1]: HTML5 forms - valid email address

garde 0.6.1