Stable structure StableBTreeMap principal in key

Developers
1

How can I use a principal in a key of a StableBTreeMap to filter the map using range?

Assuming my keys do not contains only the principal, how can I provide a min and max value for the principal?

// Pseudo code
my_stable_btree_map.range(filter()).collect();

fn filter() -> impl RangeBounds<MyKey> {
   let start = MyKey {
      something: 123,
      principal: ????????? // min
   }

   let end = MyKey {
      something: 3456,
      principal: ????????? // max
   }

   start..end
}
2

Shout-out to @frederikrothenberger for sharing the solution:

pub const PRINCIPAL_MIN: Principal = Principal::from_slice(&[]);
pub const PRINCIPAL_MAX: Principal = Principal::from_slice(&[255; 29]);

pub fn filter_satellites_analytics(
    GetAnalytics {
        from,
        to,
        satellite_id,
    }: &GetAnalytics,
) -> impl RangeBounds<AnalyticSatelliteKey> {
    let start_key = AnalyticSatelliteKey {
        satellite_id: satellite_id.unwrap_or(PRINCIPAL_MIN),
        collected_at: from.unwrap_or(u64::MIN),
        key: "".to_string(),
    };

    let end_key = AnalyticSatelliteKey {
        satellite_id: satellite_id.unwrap_or(PRINCIPAL_MAX),
        collected_at: to.unwrap_or(u64::MAX),
        key: "".to_string(),
    };

    start_key..end_key
}
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