post.rs

// alternatively, return a mutable DataResource
// and map the id and other metadata afterwards
let resource = match event.value {

    // simple
    EventValue::String(x) => DataResource{ id: event.id, value: DataResourcePayload::String(x)},
    EventValue::Float(x) => DataResource{ id: event.id, value: DataResourcePayload::Float(x)},
    EventValue::Int(x) => DataResource{ id: event.id, value: DataResourcePayload::Int(x)},
    EventValue::Bool(x) => DataResource{ id: event.id, value: DataResourcePayload::Bool(x)},

    // special care with incremental additions
    EventValue::CaptionedImage(x) => {
        // <save to some blob storage>
        let ref_id = Uuid::new_v4().to_string();

        DataResource { 
            id: event.id,
            value: DataResourcePayload::CaptionedImage(
                CaptionedImagePayload { caption: x.caption, blob_storage_ref_id: ref_id }
            )
        }
    }
};

match db.save(resource) {
    Ok(_) => Result::Ok(()),
    Err(x) => Result::Err(x)
}