Make model path mandatory in export to ONNX and restart the build. (dotnet#641)

Author: codemzs

src/Microsoft.ML.Onnx/SaveOnnxCommand.cs

@@ -28,7 +28,7 @@ public sealed class SaveOnnxCommand : DataCommand.ImplBase<SaveOnnxCommand.Argum
 
         public sealed class Arguments : DataCommand.ArgumentsBase
         {
-            [Argument(ArgumentType.AtMostOnce, HelpText = "The path to write the output ONNX to.", SortOrder = 1)]
+            [Argument(ArgumentType.Required, HelpText = "The path to write the output ONNX to.", SortOrder = 1)]
             public string Onnx;
 
             [Argument(ArgumentType.AtMostOnce, HelpText = "The path to write the output JSON to.", SortOrder = 2)]
@@ -74,13 +74,18 @@ public SaveOnnxCommand(IHostEnvironment env, Arguments args)
                 : base(env, args, LoadName)
         {
             Host.CheckValue(args, nameof(args));
+            Host.CheckNonWhiteSpace(args.Onnx, nameof(args.Onnx));
+
             Utils.CheckOptionalUserDirectory(args.Onnx, nameof(args.Onnx));
-            _outputModelPath = string.IsNullOrWhiteSpace(args.Onnx) ? null : args.Onnx;
+            _outputModelPath = args.Onnx;
             _outputJsonModelPath = string.IsNullOrWhiteSpace(args.Json) ? null : args.Json;
-            if (args.Name == null && _outputModelPath != null)
+            if (args.Name == null)
                 _name = Path.GetFileNameWithoutExtension(_outputModelPath);
-            else if (!string.IsNullOrWhiteSpace(args.Name))
+            else
+            {
+                Host.CheckNonWhiteSpace(args.Name, nameof(args.Name));
                 _name = args.Name;
+            }
 
             _loadPredictor = args.LoadPredictor;
             _inputsToDrop = CreateDropMap(args.InputsToDropArray ?? args.InputsToDrop?.Split(','));
@@ -237,12 +242,9 @@ private void Run(IChannel ch)
             }
 
             var model = ctx.MakeModel();
-            if (_outputModelPath != null)
-            {
-                using (var file = Host.CreateOutputFile(_outputModelPath))
-                using (var stream = file.CreateWriteStream())
-                    model.WriteTo(stream);
-            }
+            using (var file = Host.CreateOutputFile(_outputModelPath))
+            using (var stream = file.CreateWriteStream())
+                model.WriteTo(stream);
 
             if (_outputJsonModelPath != null)
             {

src/Microsoft.ML/Models/OnnxConverter.cs

@@ -28,7 +28,7 @@ public sealed partial class OnnxConverter
         /// path defined through the Json option.
         ///
         /// This API supports the following arguments:
-        /// <see cref="Onnx"/> indicates the file to write the ONNX protocol buffer file to. This is optional.
+        /// <see cref="Onnx"/> indicates the file to write the ONNX protocol buffer file to. This is required.
         /// <see cref="Json"/> indicates the file to write the JSON representation of the ONNX model. This is optional.
         /// <see cref="Name"/> indicates the name property in the ONNX model. If left unspecified, it will
         /// be the extension-less name of the file specified in the onnx indicates the protocol buffer file

test/BaselineOutput/Common/EntryPoints/core_manifest.json

@@ -2417,10 +2417,9 @@
           "Name": "Onnx",
           "Type": "String",
           "Desc": "The path to write the output ONNX to.",
-          "Required": false,
+          "Required": true,
           "SortOrder": 1.0,
-          "IsNullable": false,
-          "Default": null
+          "IsNullable": false
         },
         {
           "Name": "Json",