diff --git a/src/yopa.rs b/src/yopa.rs
index 74029af..4d0c402 100644
--- a/src/yopa.rs
+++ b/src/yopa.rs
@@ -136,7 +136,7 @@ pub struct InMemoryStorage {
 
     data_objects: HashMap<ID, data::Object>,
     data_relations: HashMap<ID, data::Relation>,
-    data_properties: HashMap<ID, data::Value>,
+    data_values: HashMap<ID, data::Value>,
 }
 
 fn next_id() -> ID {
@@ -227,7 +227,7 @@ impl InMemoryStorage {
             let _ = map_drain_filter(&mut self.data_objects, |_k, v| v.object_tpl_id == id);
 
             // Remove property values
-            let _ = map_drain_filter(&mut self.data_properties, |_k, v| removed_prop_ids.contains(&v.prop_tpl_id));
+            let _ = map_drain_filter(&mut self.data_values, |_k, v| removed_prop_ids.contains(&v.prop_tpl_id));
 
             // Remove relations
             let _ = map_drain_filter(&mut self.data_relations, |_k, v| removed_relation_ids.contains(&v.rel_tpl_id));
@@ -248,7 +248,7 @@ impl InMemoryStorage {
             // Remove related property templates
             let removed_prop_tpl_ids = map_drain_filter(&mut self.tpl_properties, |_k, v| v.parent_tpl_id == id).keys();
 
-            let _ = map_drain_filter(&mut self.data_properties, |_k, v| removed_prop_tpl_ids.contains(&v.prop_tpl_id));
+            let _ = map_drain_filter(&mut self.data_values, |_k, v| removed_prop_tpl_ids.contains(&v.prop_tpl_id));
 
             // Related object remain untouched, so there can be a problem with orphans. This is up to the application to deal with.
 
@@ -261,10 +261,61 @@ impl InMemoryStorage {
     pub fn delete_property_template(&mut self, id : ID) -> Result<model::PropertyTemplate, StorageError> {
         return if let Some(t) = self.tpl_properties.remove(&id) {
             // Remove relations
-            let _ = map_drain_filter(&mut self.data_properties, |_k, v| v.prop_tpl_id == id);
+            let _ = map_drain_filter(&mut self.data_values, |_k, v| v.prop_tpl_id == id);
             Ok(t)
         } else {
             Err(StorageError::NotExist("property template"))
         }
     }
+
+    // DATA
+
+    pub fn insert_object(&mut self, mut obj : data::Object) -> Result<ID, StorageError> {
+        if !self.tpl_objects.contains_key(&obj.object_tpl_id) {
+            return Err(StorageError::NotExist("object template"));
+        }
+
+        let id = next_id();
+        obj.id = id;
+        self.data_objects.insert(id, obj);
+        Ok(id)
+    }
+
+    pub fn insert_value(&mut self, mut obj : data::Value) -> Result<ID, StorageError> {
+        if !self.tpl_properties.contains_key(&obj.prop_tpl_id) {
+            return Err(StorageError::NotExist("property template"));
+        }
+
+        if !self.data_objects.contains_key(&obj.object_id) {
+            return Err(StorageError::NotExist("parent object"));
+        }
+
+        // TODO validate if it already exists
+
+        let id = next_id();
+        obj.id = id;
+        self.data_values.insert(id, obj);
+        Ok(id)
+    }
+
+    pub fn insert_relation(&mut self, mut rel: data::Relation) -> Result<ID, StorageError> {
+        if !self.tpl_relations.contains_key(&rel.rel_tpl_id) {
+            return Err(StorageError::NotExist("relation template"));
+        }
+
+        if !self.data_objects.contains_key(&rel.object_id) {
+            return Err(StorageError::NotExist("parent object"));
+        }
+
+        if !self.data_objects.contains_key(&rel.related_id) {
+            return Err(StorageError::NotExist("related object"));
+        }
+
+        // TODO validate if it already exists
+
+        let id = next_id();
+        rel.id = id;
+        self.data_relations.insert(id, rel);
+        Ok(id)
+    }
 }