Optimize get_root() to filter data at backend using XPath

[Copilot]

The get_root(path) method fetches the entire configuration tree from the backend then parses client-side to find the requested element. For large configurations, this wastes bandwidth and memory.

Changes

• rpc_config_get(): Added optional xpath parameter (default /) to filter data at the NETCONF backend
• path_to_xpath(): New helper converts simplified path notation to XPath (handles 0-to-1-based index conversion, quote normalization)
• get_root(): When path is provided, converts to XPath and requests only relevant subtree from backend

Example

Before:

# Fetches and parses entire configuration tree
root = clixon.get_root()
device = get_path(root, "devices/device[0]")

After (optimized):

# Backend returns only devices/device[1] subtree
device = clixon.get_root("devices/device[0]")

Backward compatible - all existing code continues to work unchanged.

Original prompt

Problem

The get_root(path) method in clixon/clixon.py currently:

1. Fetches the entire configuration tree from the backend using rpc_config_get() with XPath filter / (all data)
2. Then uses client-side parsing with get_path() to locate the specific element

This approach is inefficient as it:

• Transfers large amounts of unnecessary data over the network
• Requires parsing the entire configuration tree in memory
• Causes unnecessary overhead when only a small subset of data is needed

Solution

Optimize the backend data retrieval by:

1. Modify rpc_config_get() in clixon/netconf.py:

   • Add an optional xpath parameter (default to / for backward compatibility)
   • Use the provided xpath in the XPath filter instead of always using /

2. Update get_root() in clixon/clixon.py:

   • When a path parameter is provided, convert the path to an XPath expression
   • Pass the XPath directly to rpc_config_get() instead of requesting all data
   • Remove the get_path() call since the backend now returns only the requested element
   • Keep the existing behavior when no path is provided

3. Update Tests:

   • Add tests for rpc_config_get() with custom XPath filters
   • Add tests for get_root() with various path formats

Benefits

• Reduces network bandwidth usage
• Decreases memory footprint by not parsing unnecessary data
• Improves performance for large configuration trees
• Maintains backward compatibility (default behavior unchanged)
• Provides more efficient data retrieval for common use cases like get_root("devices/device[0]")

This pull request was created from Copilot chat.

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