Crate ser_nix 

ser_nix

Nix is a declarative, atomic, and reproducible package manager that is configured with the nix programming language

{
  a = 1;
  b = "Hello World";
  submap.foo = "bar";
}

ser_nix can be used to serialise arbitrary rust types into corresponding nix data types. As the name implies, ser_nix does not provide deserialisation capabilities, as the process for doing so is non-trivial, and requires evaluating nix code.

ser_nix tries to follow the idioms of other serde libraries, like serde_json.

use serde::Serialize;
use ser_nix::to_string;

#[derive(Serialize)]
struct Person {
    name: String,
    age: u8,
}

let cm = Person {
    name: "John Doe".into(),
    age: 65,
};

let serialized = to_string(&cm).unwrap();

let expected = "{\n  name = \"John Doe\";\n  age = 65;\n}".to_string();

assert_eq!(serialized, expected);

Option and None values

Following serde_json conventions, Option::None values are serialized as null by default. To omit fields when they are None, use the #[serde(skip_serializing_if = "Option::is_none")] attribute:

use serde::Serialize;
use ser_nix::to_string;

#[derive(Serialize)]
struct Config {
    enabled: Option<bool>,
    #[serde(skip_serializing_if = "Option::is_none")]
    optional: Option<String>,
}

let config = Config {
    enabled: None,
    optional: None,
};

let serialized = to_string(&config).unwrap();
// Output: { enabled = null; }

Nix paths

In Nix, paths like ./foo.nix or /etc/nixos/configuration.nix are written without quotes. There are two ways to serialize paths as unquoted Nix paths:

Using NixPathBuf wrapper type

use serde::Serialize;
use ser_nix::{to_string, NixPathBuf};

#[derive(Serialize)]
struct NixConfig {
    source: NixPathBuf,
}

let config = NixConfig {
    source: NixPathBuf::new("./hardware-configuration.nix"),
};

let serialized = to_string(&config).unwrap();
// Output: { source = ./hardware-configuration.nix; }

For borrowed paths, use NixPath<'a>:

use ser_nix::{to_string, NixPath};
use std::path::Path;

let path = Path::new("./config.nix");
let result = to_string(&NixPath::new(path)).unwrap();
assert_eq!(result, "./config.nix");

Using #[serde(serialize_with = "...")]

use serde::Serialize;
use ser_nix::to_string;
use std::path::PathBuf;

#[derive(Serialize)]
struct NixConfig {
    #[serde(serialize_with = "ser_nix::as_nix_path")]
    source: PathBuf,
    description: String,
}

let config = NixConfig {
    source: PathBuf::from("./hardware-configuration.nix"),
    description: "Hardware config".to_string(),
};

let serialized = to_string(&config).unwrap();
// source is unquoted: ./hardware-configuration.nix
// description is quoted: "Hardware config"

Structs

NixLiteral

A raw Nix expression that serializes without quotes.

NixPath

A borrowed path that serializes as a Nix path literal.

NixPathBuf

An owned path that serializes as a Nix path literal.

Enums

Error

Error type for ser_nix serialisation

Functions

as_literal

Serialize a string as a raw Nix expression (without quotes).

as_nix_path

Serialize a Path or PathBuf as a Nix path literal.

as_optional_literal

Serialize an Option<String> as a raw Nix expression, or null if None.

as_optional_nix_path

Serialize an Option<PathBuf> or Option<&Path> as a Nix path literal, or null if None.

to_string

Serialise the given data structure as a String of Nix data