Crate serde_constant

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Expand description

This crate provides a type that can represent a single-const serde value. For example, asserting that a particular bool is always true. You can use this for disambiguation in serde(untagged) structures, or just for validation.


use serde_constant::ConstBool;
struct Foo {
    bar: String,
    baz: ConstBool<true>,

assert!(serde_json::from_value::<Foo>(json!({ "bar": "quux", "baz": true })).is_ok());
assert!(serde_json::from_value::<Foo>(json!({ "bar": "quux", "baz": false })).is_err());
use serde_constant::ConstI64;
// int tags? No problem!
enum Foo {
    Bar {
        tag: ConstI64<1>,
    Baz {
        tag: ConstI64<2>,
        x: Option<String>,
    serde_json::from_value(json!({ "tag": 2, "x": null }))?,
    // would have been Bar if `tag` were just `i64`
    Foo::Baz { x: None, .. },