serde-bool

Single-side boolean deserializers.

Examples

Supporting serde untagged enums where only one boolean value is valid, allowing fallthrough to the next variant. Avoids need to wrap all fields in Option<_> just in case feature is disabled.

#[derive(Debug, serde::Deserialize)]
struct Config {
    feature: FeatureConfig,
}

#[derive(Debug, serde::Deserialize)]
#[serde(untagged)]
enum FeatureConfig {
    Disabled {
        enabled: serde_bool::False
    },

    Enabled {
        #[serde(default)]
        enabled: serde_bool::True,
        key: String,
        secret: String,
    }
}

// disabled variant is matched
let config = toml::from_str::<Config>(r#"
    [feature]
    enabled = false
"#).unwrap();
assert!(matches!(config.feature, FeatureConfig::Disabled { .. }));

// if the type used `enabled: bool`, this would cause issues and require Option<_> wrappers plus
// further validation... instead an error is returned immediately regarding the missing fields
let config = toml::from_str::<Config>(r#"
    [feature]
    enabled = true
"#).unwrap_err();

// using a `#[serde(default)]` annotation makes `enabled = true` optional here
let config = toml::from_str::<Config>(r#"
    [feature]
    key = "foo"
    secret = "bar"
"#).unwrap();
assert!(matches!(config.feature, FeatureConfig::Enabled { .. }));

// extra keys can exists in the disabled case, but as usual will not be captured
let config = toml::from_str::<Config>(r#"
    [feature]
    enabled = false
    key = "foo"
    secret = "bar"
"#).unwrap();
assert!(matches!(config.feature, FeatureConfig::Disabled { .. }));