Add alternative DB interface and implementation

Signed-off-by: Lee Smet <lee.smet@hotmail.com>

heromodels/src/models/core/mod.rs

@@ -3,5 +3,5 @@ pub mod model;
 pub mod comment;
 
 // Re-export key types for convenience
-pub use model::{Model, BaseModelData, IndexKey, IndexKeyBuilder};
+pub use model::{Model, BaseModelData, IndexKey, IndexKeyBuilder, Index};
 pub use comment::Comment;

heromodels/src/models/core/model.rs

@@ -73,6 +73,15 @@ pub trait Model: Debug + Clone + Serialize + for<'de> Deserialize<'de> + Send +
     }
 }
 
+/// An identifier for an index in the DB
+pub trait Index {
+    /// The model for which this is an index in the database
+    type Model: Model;
+
+    /// The key of this index
+    fn key() -> &'static str;
+}
+
 /// Base struct that all models should include
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct BaseModelData {