Fix typo in functional model input flattening (keras-team#402)

* Fix typo in functional model input flattening

* Add unit test

keras_core/models/functional.py

@@ -211,7 +211,7 @@ def _flatten_to_reference_inputs(self, inputs, allow_extra_keys=True):
         if isinstance(inputs, dict):
             ref_inputs = self._inputs_struct
             if not nest.is_nested(ref_inputs):
-                ref_inputs = [self._nested_inputs]
+                ref_inputs = [self._inputs_struct]
             if isinstance(ref_inputs, dict):
                 # In the case that the graph is constructed with dict input
                 # tensors, We will use the original dict key to map with the

keras_core/models/functional_test.py

@@ -99,6 +99,24 @@ def test_basic_flow_dict_io(self):
         out_val = model(in_val)
         self.assertEqual(out_val.shape, (2, 4))
 
+    def test_named_input_dict_io(self):
+        input_a = Input(shape=(3,), batch_size=2, name="a")
+        x = layers.Dense(5)(input_a)
+        outputs = layers.Dense(4)(x)
+
+        model = Functional(input_a, outputs)
+
+        # Eager call
+        in_val = {"a": np.random.random((2, 3))}
+        out_val = model(in_val)
+        self.assertEqual(out_val.shape, (2, 4))
+
+        # Symbolic call
+        input_a_2 = Input(shape=(3,), batch_size=2)
+        in_val = {"a": input_a_2}
+        out_val = model(in_val)
+        self.assertEqual(out_val.shape, (2, 4))
+
     def test_layer_getters(self):
         # Test mixing ops and layers
         input_a = Input(shape=(3,), batch_size=2, name="input_a")