get.rs

match db.retrieve(&id) {
    Ok(c) => match c {
        Some(d) => {
            /* map DataResource -> EventEntity */
            let ret = match d.value {
                DataResourcePayload::String(x) => EventEntity{ id: d.id, value: EventValue::String(x)},
                DataResourcePayload::Float(x) => EventEntity{ id: d.id, value: EventValue::Float(x)},
                DataResourcePayload::Int(x) => EventEntity{ id: d.id, value: EventValue::Int(x)},
                DataResourcePayload::Bool(x) => EventEntity{ id: d.id, value: EventValue::Bool(x)},
                DataResourcePayload::CaptionedImage(x) => {
                    // fetch from blob storage
                    let img_b64 = "<get from blob storage>".into();

                    EventEntity { 
                        id: d.id, 
                        value: EventValue::CaptionedImage(
                            CaptionedImageValue {
                                caption: x.caption,
                                contents_b64: img_b64
                            }
                        )
                    }
                }
            };

            Result::Ok(Json(ret))
        },
        None => Result::Err(None)
    },
    Err(x) => Result::Err(Some(x))
}