fix: Use incremental ID

heromodels/src/db.rs

@@ -32,9 +32,16 @@ where
     /// Get an object from its ID. This does not use an index lookup
     fn get_by_id(&self, id: u32) -> Result<Option<V>, Error<Self::Error>>;
 
-    /// Store an item in the DB and return the assigned ID.
-    /// This method does not modify the original model.
-    fn set(&self, value: &V) -> Result<u32, Error<Self::Error>>;
+    /// Store an item in the DB and return the assigned ID and the updated model.
+    ///
+    /// # Important Notes
+    /// - This method does not modify the original model passed as an argument.
+    /// - For new models (with ID 0), an ID will be auto-generated by OurDB.
+    /// - The returned model will have the correct ID and should be used instead of the original model.
+    /// - The original model should not be used after calling this method, as it may have
+    ///   an inconsistent state compared to what's in the database.
+    /// - ID 0 is reserved for new models and should not be used for existing models.
+    fn set(&self, value: &V) -> Result<(u32, V), Error<Self::Error>>;
 
     /// Delete all items from the db with a given index.
     fn delete<I, Q>(&self, key: &Q) -> Result<(), Error<Self::Error>>
@@ -46,8 +53,11 @@ where
     /// Delete an object with a given ID
     fn delete_by_id(&self, id: u32) -> Result<(), Error<Self::Error>>;
 
-    /// Get all objects from the colelction
+    /// Get all objects from the collection
     fn get_all(&self) -> Result<Vec<V>, Error<Self::Error>>;
+
+    /// Begin a transaction for this collection
+    fn begin_transaction(&self) -> Result<Box<dyn Transaction<Error = Self::Error>>, Error<Self::Error>>;
 }
 
 /// Errors returned by the DB implementation
@@ -59,6 +69,14 @@ pub enum Error<E> {
     Decode(bincode::error::DecodeError),
     /// Error encoding a model for storage
     Encode(bincode::error::EncodeError),
+    /// Invalid ID used (e.g., using ID 0 for an existing model)
+    InvalidId(String),
+    /// ID mismatch (e.g., expected ID 5 but got ID 6)
+    IdMismatch(String),
+    /// ID collision (e.g., trying to create a model with an ID that already exists)
+    IdCollision(String),
+    /// Type error (e.g., trying to get a model of the wrong type)
+    TypeError,
 }
 
 impl<E> From<bincode::error::DecodeError> for Error<E> {
@@ -72,3 +90,21 @@ impl<E> From<bincode::error::EncodeError> for Error<E> {
         Error::Encode(value)
     }
 }
+
+/// A transaction that can be committed or rolled back
+pub trait Transaction {
+    /// Error type for transaction operations
+    type Error: std::fmt::Debug;
+
+    /// Begin a transaction
+    fn begin(&self) -> Result<(), Error<Self::Error>>;
+
+    /// Commit a transaction
+    fn commit(&self) -> Result<(), Error<Self::Error>>;
+
+    /// Roll back a transaction
+    fn rollback(&self) -> Result<(), Error<Self::Error>>;
+
+    /// Check if a transaction is active
+    fn is_active(&self) -> bool;
+}