diff --git a/include/matador/object/collection_proxy.hpp b/include/matador/object/collection_proxy.hpp
index 6b9ca45..791aae3 100644
--- a/include/matador/object/collection_proxy.hpp
+++ b/include/matador/object/collection_proxy.hpp
@@ -24,7 +24,9 @@ struct relation_iterator_traits;
 
 template < typename Type, typename OwnerType >
 struct relation_iterator_traits<relation<OwnerType, Type>> {
-
+  static Type& value(relation<OwnerType, Type>& re) {
+    return re.relation().value();
+  }
 };
 
 template<typename Type, typename RelationType = Type>
@@ -33,6 +35,7 @@ public:
   using value_type = Type;
   using reference = Type&;
   using pointer = Type*;
+  using relation_type = RelationType;
   using iterator_category = std::forward_iterator_tag;
 
   collection_proxy_iterator() = default;
@@ -52,6 +55,9 @@ public:
     return !operator==(other);
   }
 
+  relation_type& relation() {
+    return *it_;
+  }
 private:
   typename std::vector<RelationType>::iterator it_;
 };
@@ -70,13 +76,10 @@ public:
 
   virtual iterator begin() = 0;
   virtual iterator end() = 0;
-  virtual const_iterator begin() const = 0;
-  virtual const_iterator end() const = 0;
 
-  [[nodiscard]] virtual size_t size() const = 0;
-  [[nodiscard]] virtual bool empty() const = 0;
-//  virtual collection_proxy_iterator<Type> begin() = 0;
-//  virtual collection_proxy_iterator<Type> end() = 0;
+  [[nodiscard]] virtual size_t size() = 0;
+  [[nodiscard]] virtual bool empty() = 0;
+
   [[nodiscard]] virtual const utils::identifier& owner_id() const = 0;
 
 protected:
@@ -117,23 +120,19 @@ public:
     return items_.end();
   }
 
-  const_iterator begin() const override {
+  void push_back(const value_type& value) override {
     resolve();
-    return items_.begin();
+    items_.push_back(value);
+  }
+  [[nodiscard]] size_t size() override {
+    resolve();
+    return items_.size();
+  }
+  [[nodiscard]] bool empty() override {
+    resolve();
+    return items_.empty();
   }
 
-  const_iterator end() const override {
-    resolve();
-    return items_.end();
-  }
-  // const std::vector<Type>& items() const {
-  //   resolve();
-  //   return items_;
-  // }
-  // std::vector<Type>& items() {
-  //   resolve();
-  //   return items_;
-  // }
 private:
   void resolve() {
     if (loaded_) {
diff --git a/test/core/CMakeLists.txt b/test/core/CMakeLists.txt
index e17f760..9a75a91 100644
--- a/test/core/CMakeLists.txt
+++ b/test/core/CMakeLists.txt
@@ -5,6 +5,7 @@ list(APPEND CMAKE_MODULE_PATH ${catch2_SOURCE_DIR}/extras)
 add_executable(CoreTests
   ../backends/SchemaFixture.hpp
   logger/LoggerTest.cpp
+  object/CollectionTest.cpp
   object/ObjectCacheTest.cpp
   object/ObjectTest.cpp
   object/PrimaryKeyResolverTest.cpp
diff --git a/test/core/object/CollectionTest.cpp b/test/core/object/CollectionTest.cpp
new file mode 100644
index 0000000..015e0ae
--- /dev/null
+++ b/test/core/object/CollectionTest.cpp
@@ -0,0 +1,7 @@
+#include <catch2/catch_test_macros.hpp>
+
+#include "matador/object/collection.hpp"
+#include "matador/object/object.hpp"
+
+TEST_CASE("Test collection", "[collection]") {
+}
\ No newline at end of file