Fix graph instance in InputLayer.

src/TensorFlowNET.Core/Graphs/FuncGraph.cs

@@ -17,8 +17,8 @@ namespace Tensorflow.Graphs
         IntPtr func_handle;
         public string FuncName => _graph_key;
 
-        public Tensors Inputs { get; set; }
-        public Tensors Outputs { get; set; }
+        public Tensors Inputs { get; set; } = new Tensors();
+        public Tensors Outputs { get; set; } = new Tensors();
         public Dictionary<string, string> Attrs { get; set; }
 
         public Dictionary<long, (Tensor, Tensor)> _captures 
@@ -175,14 +175,7 @@ namespace Tensorflow.Graphs
         void add_capture(Tensor tensor, Tensor placeholder)
         {
             _captures.Add(tensor.Id, (tensor, placeholder));
-            if (Inputs == null)
-                Inputs = new Tensors(placeholder);
-            else
-            {
-                var inputs = Inputs.ToList();
-                inputs.Add(placeholder);
-                Inputs = new Tensors(inputs.ToArray());
-            }
+            Inputs.Add(placeholder);
         }
 
         Tensor _create_substitute_placeholder(Tensor value, 

src/TensorFlowNET.Core/Sessions/BaseSession.cs

@@ -39,7 +39,8 @@ namespace Tensorflow
         public BaseSession(string target = "", Graph g = null, ConfigProto config = null, Status status = null)
         {
             _graph = g ?? ops.get_default_graph();
-            _graph.as_default();
+            if (!_graph.building_function)
+                _graph.as_default();
             _target = Encoding.UTF8.GetBytes(target);
 
             using (var opts = new SessionOptions(target, config))

src/TensorFlowNET.Keras/Layers/Core/InputLayer.cs

@@ -58,9 +58,6 @@ namespace Tensorflow.Keras.Layers
                 args.DType = args.InputTensor == null ? tf.float32 : args.InputTensor.dtype;
             }
 
-            // In graph mode, create a graph placeholder to call the layer on.
-            tf.Context.graph_mode();
-
             if (args.InputTensor == null)
             {
                 if (args.InputShape != null)
@@ -74,6 +71,9 @@ namespace Tensorflow.Keras.Layers
                     args.BatchInputShape = null;
                 }
 
+                var graph = keras.backend.get_graph();
+                graph.as_default();
+
                 args.InputTensor = keras.backend.placeholder(
                     shape: BatchInputShape,
                     dtype: DType,
@@ -81,8 +81,8 @@ namespace Tensorflow.Keras.Layers
                     sparse: args.Sparse,
                     ragged: args.Ragged);
 
-
                 isPlaceholder = true;
+                tf.Context.restore_mode();
             }
 
             // Create an input node to add to self.outbound_node
@@ -97,8 +97,6 @@ namespace Tensorflow.Keras.Layers
             typeSpec = new TensorSpec(args.InputTensor.TensorShape,
                 dtype: args.InputTensor.dtype,
                 name: Name);
-
-            tf.Context.restore_mode();
         }
 
         public static InputLayer from_config(LayerArgs args)

src/TensorFlowNET.Keras/Utils/base_layer_utils.cs

@@ -151,23 +151,12 @@ namespace Tensorflow.Keras.Utils
 
                     // recursively
                     CreateKerasHistoryHelper(layer_inputs, processed_ops, created_layers);
-                    Layer op_layer = null;
-                    /*var op_layer = new TensorFlowOpLayer(new TensorFlowOpLayerArgs
+                    Layer op_layer = new TensorFlowOpLayer(new TensorFlowOpLayerArgs
                     {
                         NodeDef = op.node_def,
                         Constants = constants,
                         Name = op.name
-                    });*/
-                    op_layer = op.type switch
-                    {
-                        // "AddV2" => keras.layers.Add(),
-                        _ => new TensorFlowOpLayer(new TensorFlowOpLayerArgs
-                        {
-                            NodeDef = op.node_def,
-                            Constants = constants,
-                            Name = op.name
-                        })
-                    };
+                    });
                     created_layers.Add(op_layer);
                     op_layer.SetConnectivityMetadata(layer_inputs, op.outputs);
                     processed_ops.Add(op);