Improve ckpt_export (#6965)

Fixes #6953

### Description


### Types of changes
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] Non-breaking change (fix or new feature that would not break
existing functionality).
- [ ] Breaking change (fix or new feature that would cause existing
functionality to change).
- [ ] New tests added to cover the changes.
- [ ] Integration tests passed locally by running `./runtests.sh -f -u
--net --coverage`.
- [ ] Quick tests passed locally by running `./runtests.sh --quick
--unittests --disttests`.
- [ ] In-line docstrings updated.
- [ ] Documentation updated, tested `make html` command in the `docs/`
folder.

---------

Signed-off-by: KumoLiu <yunl@nvidia.com>
Signed-off-by: YunLiu <55491388+KumoLiu@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>

Author: 3 people

monai/bundle/scripts.py

@@ -1214,9 +1214,13 @@ def ckpt_export(
 
     Args:
         net_id: ID name of the network component in the config, it must be `torch.nn.Module`.
+            Default to "network_def".
         filepath: filepath to export, if filename has no extension it becomes `.ts`.
+            Default to "models/model.ts" under "os.getcwd()" if `bundle_root` is not specified.
         ckpt_file: filepath of the model checkpoint to load.
+            Default to "models/model.pt" under "os.getcwd()" if `bundle_root` is not specified.
         meta_file: filepath of the metadata file, if it is a list of file paths, the content of them will be merged.
+            Default to "configs/metadata.json" under "os.getcwd()" if `bundle_root` is not specified.
         config_file: filepath of the config file to save in TorchScript model and extract network information,
             the saved key in the TorchScript model is the config filename without extension, and the saved config
             value is always serialized in JSON format no matter the original file format is JSON or YAML.
@@ -1250,9 +1254,10 @@ def ckpt_export(
     )
     _log_input_summary(tag="ckpt_export", args=_args)
     (
+        config_file_,
         filepath_,
         ckpt_file_,
-        config_file_,
+        bundle_root_,
         net_id_,
         meta_file_,
         key_in_ckpt_,
@@ -1261,10 +1266,11 @@ def ckpt_export(
         converter_kwargs_,
     ) = _pop_args(
         _args,
-        "filepath",
-        "ckpt_file",
         "config_file",
-        net_id="",
+        filepath=None,
+        ckpt_file=None,
+        bundle_root=os.getcwd(),
+        net_id=None,
         meta_file=None,
         key_in_ckpt="",
         use_trace=False,
@@ -1275,9 +1281,22 @@ def ckpt_export(
     parser = ConfigParser()
 
     parser.read_config(f=config_file_)
-    if meta_file_ is not None:
+    meta_file_ = os.path.join(bundle_root_, "configs", "metadata.json") if meta_file_ is None else meta_file_
+    filepath_ = os.path.join(bundle_root_, "models", "model.ts") if filepath_ is None else filepath_
+    ckpt_file_ = os.path.join(bundle_root_, "models", "model.pt") if ckpt_file_ is None else ckpt_file_
+    if not os.path.exists(ckpt_file_):
+        raise FileNotFoundError(f'Checkpoint file "{ckpt_file_}" not found, please specify it in argument "ckpt_file".')
+    if os.path.exists(meta_file_):
         parser.read_meta(f=meta_file_)
 
+    net_id_ = "network_def" if net_id_ is None else net_id_
+    try:
+        parser.get_parsed_content(net_id_)
+    except ValueError as e:
+        raise ValueError(
+            f'Network definition "{net_id_}" cannot be found in "{config_file_}", specify name with argument "net_id".'
+        ) from e
+
     # the rest key-values in the _args are to override config content
     for k, v in _args.items():
         parser[k] = v

tests/test_bundle_ckpt_export.py

@@ -75,6 +75,29 @@ def test_export(self, key_in_ckpt, use_trace):
             self.assertTrue("meta_file" in json.loads(extra_files["def_args.json"]))
             self.assertTrue("network_def" in json.loads(extra_files["inference.json"]))
 
+    @parameterized.expand([TEST_CASE_1, TEST_CASE_2, TEST_CASE_3])
+    def test_default_value(self, key_in_ckpt, use_trace):
+        config_file = os.path.join(os.path.dirname(__file__), "testing_data", "inference.json")
+        with tempfile.TemporaryDirectory() as tempdir:
+            def_args = {"meta_file": "will be replaced by `meta_file` arg"}
+            def_args_file = os.path.join(tempdir, "def_args.yaml")
+            ckpt_file = os.path.join(tempdir, "models/model.pt")
+            ts_file = os.path.join(tempdir, "models/model.ts")
+
+            parser = ConfigParser()
+            parser.export_config_file(config=def_args, filepath=def_args_file)
+            parser.read_config(config_file)
+            net = parser.get_parsed_content("network_def")
+            save_state(src=net if key_in_ckpt == "" else {key_in_ckpt: net}, path=ckpt_file)
+
+            # check with default value
+            cmd = ["coverage", "run", "-m", "monai.bundle", "ckpt_export", "--key_in_ckpt", key_in_ckpt]
+            cmd += ["--config_file", config_file, "--bundle_root", tempdir]
+            if use_trace == "True":
+                cmd += ["--use_trace", use_trace, "--input_shape", "[1, 1, 96, 96, 96]"]
+            command_line_tests(cmd)
+            self.assertTrue(os.path.exists(ts_file))
+
 
 if __name__ == "__main__":
     unittest.main()