Derive Macro serde_piecewise_default_derive::DeserializePiecewiseDefault

#[derive(DeserializePiecewiseDefault)]

See the parent crate documentation for a high-level overview.

Implementation Details

#[derive(DeserializePiecewiseDefault)]
struct Example {
    item1: i8,
    item2: String,
}

will expand to

struct Example {
    item1: i8,
    item2: String,
}

#[derive(Deserialize)]
struct OptionExample {
    item1: Option<i8>,
    item2: Option<String>,
}

impl<'de> Deserialize<'de> for Example {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: serde::Deserializer<'de> {
        <OptionExample as Deserialize>::deserialize(deserializer)
            .map(|raw_result| {
                let OptionExample { item1, item2 } = raw_result;
                let default = <Example as Default>::default();
                let item1 = item1.unwrap_or(default.item1);
                let item2 = item2.unwrap_or(default.item2);
                Example { item1, item2 }
            })
    }
}