Added some minor fixes to robot.save method.

onshape_api/robot.py

@@ -10,7 +10,7 @@
 import xml.etree.ElementTree as ET
 from enum import Enum
 from pathlib import Path
-from typing import Optional
+from typing import Optional, Union
 
 from lxml import etree
 
@@ -113,6 +113,8 @@ def __init__(
         self.assets = assets
         self.type = robot_type
 
+        self._parent_directory: Union[str, None] = None
+
         self.element: ET.Element = element if element is not None else self.to_xml(robot_type=self.type)
         self.tree: ET.ElementTree = tree if tree is not None else ET.ElementTree(self.element)
 
@@ -156,6 +158,18 @@ def save(self, file_path: Optional[str] = None, download_assets: bool = True) ->
             >>> robot = Robot( ... )
             >>> robot.save()
         """
+        if file_path and self._parent_directory:
+            file_path = Path(file_path)
+            if Path(file_path).parent != Path(self._parent_directory):
+                LOGGER.warning(
+                    "Parent directory of the file path provided is "
+                    "different from the parent directory of the URDF file."
+                )
+                LOGGER.warning(
+                    "If mesh files are present in the URDF file, "
+                    "then the URDF file will not be able to find the mesh files."
+                )
+
         path = file_path if file_path else f"{self.name}.{self.type}"
 
         if download_assets:
@@ -166,8 +180,12 @@ def save(self, file_path: Optional[str] = None, download_assets: bool = True) ->
             xml_tree = etree.fromstring(xml_str)  # noqa: S320
             pretty_xml_str = etree.tostring(xml_tree, pretty_print=True, encoding="unicode")
 
+            # Add XML declaration
+            xml_declaration = '<?xml version="1.0" ?>\n'
+            full_xml_str = xml_declaration + pretty_xml_str
+
             with open(path, "w", encoding="utf-8") as f:
-                f.write(pretty_xml_str)
+                f.write(full_xml_str)
 
         LOGGER.info(f"Robot model saved to {path}")
 
@@ -249,9 +267,11 @@ def from_urdf(cls, filename: str) -> "Robot":
                 if joint:
                     joints[joint.name] = joint
 
-        return Robot(
+        _cls = cls(
             name=name, links=links, joints=joints, assets=None, robot_type=RobotType.URDF, element=root, tree=tree
         )
+        _cls._parent_directory = Path(filename).parent
+        return _cls
 
 
 def get_robot(