diff --git a/01.workspace/heave/src/str/catalog.rs b/01.workspace/heave/src/str/catalog.rs
index 1f8e3c3..3e278e9 100644
--- a/01.workspace/heave/src/str/catalog.rs
+++ b/01.workspace/heave/src/str/catalog.rs
@@ -64,17 +64,16 @@ impl O {
     /// An `Option<T>` containing the converted entity if found, otherwise `None`.
     pub fn get<T>(&self, id: &str) -> Option<T>
     where
-        T: From<Entity>,
+        T: EAV,
     {
         let entity = self.items.get(id);
         entity.map(|e| T::from(e.clone()))
     }
 
-    /// Retrieves the first entity that matches a given class, attribute, and value.
+    /// Retrieves the first entity that matches a given attribute and value.
     ///
     /// # Arguments
     ///
-    /// * `class` - The class of the entity to search for.
     /// * `attribute` - The attribute of the entity to match.
     /// * `value` - The value of the attribute to match.
     ///
@@ -83,17 +82,16 @@ impl O {
     /// An `Option<T>` containing the converted entity if found, otherwise `None`.
     pub fn get_by_class_and_attribute<T>(
         &self,
-        class: &str,
         attribute: &str,
         value: impl Into<Value> + Clone,
     ) -> Option<T>
     where
-        T: From<Entity>,
+        T: EAV,
     {
         let mut items = self
             .items
             .values()
-            .filter(|item| item.class == class)
+            .filter(|item| item.class == T::class())
             .filter(|item| item.value_of(attribute) == Some(&value.clone().into()))
             .take(1)
             .map(|item| T::from(item.clone()));
@@ -102,28 +100,23 @@ impl O {
 
     /// Returns an iterator over entities of a specific class.
     ///
-    /// # Arguments
-    ///
-    /// * `class` - The class of the entities to list.
-    ///
     /// # Returns
     ///
     /// An iterator that yields items of type `T`.
-    pub fn list_by_class<T>(&self, class: &str) -> impl Iterator<Item = T>
+    pub fn list_by_class<T>(&self) -> impl Iterator<Item = T>
     where
-        T: From<Entity>,
+        T: EAV,
     {
         self.items
             .values()
-            .filter(move |item| item.class == class)
+            .filter(move |item| item.class == T::class())
             .map(|item| T::from(item.clone()))
     }
 
-    /// Returns an iterator over entities that match a given class, attribute, and value.
+    /// Returns an iterator over entities that match a given attribute and value.
     ///
     /// # Arguments
     ///
-    /// * `class` - The class of the entities to search for.
     /// * `attribute` - The attribute of the entities to match.
     /// * `value` - The value of the attribute to match.
     ///
@@ -132,17 +125,16 @@ impl O {
     /// An iterator that yields items of type `T`.
     pub fn list_by_class_and_attribute<T>(
         &self,
-        class: &str,
         attribute: &str,
         value: impl Into<Value> + Clone,
     ) -> impl Iterator<Item = T>
     where
-        T: From<Entity>,
+        T: EAV,
     {
         let value: Value = value.into();
         self.items
             .values()
-            .filter(move |item| item.class == class)
+            .filter(move |item| item.class == T::class())
             .filter(move |item| item.value_of(attribute) == Some(&value))
             .map(|item| T::from(item.clone()))
     }
@@ -170,11 +162,11 @@ impl O {
     }
 
     /// Loads all entities of a specific class from the database into the catalog.
-    ///
-    /// # Arguments
-    ///
-    /// * `class` - The class of the entities to load.
-    pub fn load_by_class(&mut self, class: &str) {
+    pub fn load_by_class<T>(&mut self)
+    where
+        T: EAV,
+    {
+        let class = T::class();
         let path = path::Path::new(&self.path);
         let entities = sqlite::load::by_class(path, class);
         for entity in entities {
diff --git a/01.workspace/heave/src/str/entity.rs b/01.workspace/heave/src/str/entity.rs
index f617ec8..1cb278e 100644
--- a/01.workspace/heave/src/str/entity.rs
+++ b/01.workspace/heave/src/str/entity.rs
@@ -9,7 +9,11 @@ pub struct O {
     pub attributes: std::collections::HashMap<String, Attribute>,
 }
 
-impl EAV for Entity {}
+impl EAV for Entity {
+    fn class() -> &'static str {
+        "entity"
+    }
+}
 
 impl O {
     pub fn new(class: &str) -> Self {
diff --git a/01.workspace/heave/src/trt/eav.rs b/01.workspace/heave/src/trt/eav.rs
index 40428c0..05a0267 100644
--- a/01.workspace/heave/src/trt/eav.rs
+++ b/01.workspace/heave/src/trt/eav.rs
@@ -5,6 +5,7 @@ pub trait T where
     Self: From<Entity>,
     Self: Into<Entity>,
 {
+    fn class() -> &'static str;
 }
 
 // #[cfg(test)]
diff --git a/01.workspace/heave/src/tst/intended_use.rs b/01.workspace/heave/src/tst/intended_use.rs
index 34b78cd..a1aecd4 100644
--- a/01.workspace/heave/src/tst/intended_use.rs
+++ b/01.workspace/heave/src/tst/intended_use.rs
@@ -7,7 +7,11 @@ mod tests {
         pub name: String,
         pub price: u64,
     }
-    impl EAV for Product {}
+    impl EAV for Product {
+        fn class() -> &'static str {
+            "product"
+        }
+    }
     impl From<Product> for Entity {
         fn from(value: Product) -> Entity {
             Entity::default()
@@ -208,7 +212,7 @@ mod tests {
         catalog.persist();
         // new empty catalog
         let mut catalog = Catalog::new(path.to_str().unwrap());
-        catalog.load_by_class("product");
+        catalog.load_by_class::<Product>();
         assert_eq!(catalog.items.len(), 2);
         let loaded_value_01: Product = catalog.get(&expected_value_01.id).unwrap();
         assert_eq!(loaded_value_01, expected_value_01);
diff --git a/01.workspace/heave/src/tst/rusty_budger_use.rs b/01.workspace/heave/src/tst/rusty_budger_use.rs
index ec6a97a..885c4f8 100644
--- a/01.workspace/heave/src/tst/rusty_budger_use.rs
+++ b/01.workspace/heave/src/tst/rusty_budger_use.rs
@@ -11,7 +11,11 @@ mod tests {
             pub operation_id: String,
             pub category_id: String,
         }
-        impl EAV for OperationToCategory {}
+        impl EAV for OperationToCategory {
+            fn class() -> &'static str {
+                "operation_to_category"
+            }
+        }
         impl From<OperationToCategory> for Entity {
             fn from(value: OperationToCategory) -> Entity {
                 Entity::default()
@@ -37,7 +41,11 @@ mod tests {
             pub id: String,
             pub label: String,
         }
-        impl EAV for Category {}
+        impl EAV for Category {
+            fn class() -> &'static str {
+                "category"
+            }
+        }
         impl From<Category> for Entity {
             fn from(value: Category) -> Entity {
                 Entity::default()
@@ -63,7 +71,11 @@ mod tests {
             pub amount: i64,
             pub description: String,
         }
-        impl EAV for Operation {}
+        impl EAV for Operation {
+            fn class() -> &'static str {
+                "operation"
+            }
+        }
         impl From<Operation> for Entity {
             fn from(value: Operation) -> Entity {
                 Entity::default()