Conditional Serialization (Marker)

When the marker feature is enabled, AFast::marker() sets a global marker string (default "afast") passed to afastdata’s to_bytes_with / from_bytes_with. Fields annotated with #[afast(skip_with("marker"))] are conditionally skipped during serialization/deserialization based on the active marker.

Skip Modes

• #[afast(skip)] — Field is always skipped, never serialized/deserialized. Must have a Default impl or initialization function.
• #[afast(skip_with("marker"))] — Skipped when the marker matches; serialized normally otherwise.

The marker propagates recursively into nested types (Vec<T>, Option<T>, etc.).

Generated client code (TS/JS/KT/RS) and API docs automatically exclude skipped fields.

Example

#![allow(unused)]
fn main() {
#[derive(AFastSerialize, AFastDeserialize, Tag)]
#[tag("User info")]
struct User {
    name: String,
    #[afast(skip)]
    internal_secret: String,        // always skipped
    #[afast(skip_with("afast"))]
    internal_note: String,          // skipped when marker is "afast"
}

let app = AFast::new()
    .marker("afast")  // set marker; default is already "afast"
    .service(svc)
    .http("0.0.0.0:5000");
}

Without the marker feature, serialize / deserialize use plain to_bytes / from_bytes and all fields are always included. However, #[afast(skip)] fields are still excluded from generated client code.