Update macro to use #[index] attributes

- Also use proper types for index.
 - Update DB interface to be more flexible for index params

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

heromodels/examples/custom_model_example.rs

@@ -1,37 +1,37 @@
 use heromodels::model;
-use heromodels::models::core::model::{BaseModelData, Model, Index, IndexKey};
-use serde::{Serialize, Deserialize};
+use heromodels::models::core::model::{BaseModelData, Model};
+use serde::{Deserialize, Serialize};
 
 // Define a custom attribute for indexing
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[model]
 pub struct CustomUser {
     pub base_data: BaseModelData,
-    
-    // Mark fields for indexing with a comment
-    // #[index]
+
+    // Mark fields for indexing with attributes
+    #[index]
     pub login: String,
-    
-    // #[index]
+
+    #[index]
     pub is_active: bool,
-    
+
     pub full_name: String,
 }
 
 fn main() {
     println!("Hero Models - Custom Model Example");
     println!("==================================");
-    
+
     // Example usage of the generated implementation
     println!("CustomUser DB Prefix: {}", CustomUser::db_prefix());
-    
+
     let user = CustomUser {
         base_data: BaseModelData::new(1),
         login: "johndoe".to_string(),
         is_active: true,
         full_name: "John Doe".to_string(),
     };
-    
+
     println!("\nCustomUser ID: {}", user.get_id());
     println!("CustomUser DB Keys: {:?}", user.db_keys());
-}
+}