Cannot filter based on key in XR

[jc-rode]

When trying to filter in some xpath for a "get" in IOS-XR... for instance:

'Cisco-IOS-XR-infra-statsd-oper:infra-statistics/interfaces/interface[interface-name="MgmtEth0/RP0/CPU0/0"]/generic-counters'

This will create a grpc path:

elem {
  name: "infra-statistics"
}
elem {
  name: "interfaces"
}
elem {
  name: "interface"
  key {
    key: "interface-name"
    value: "MgmtEth0/RP0/CPU0/0"
  }
}
elem {
  name: "generic-counters"
}

But this will fail due to CSCvk26949 as IOS-XR expects key values to be inserted in double quotes like this:

elem {
  name: "infra-statistics"
}
elem {
  name: "interfaces"
}
elem {
  name: "interface"
  key {
    key: "interface-name"
    value: "\"MgmtEth0/RP0/CPU0/0\""
  }
}
elem {
  name: "generic-counters"
}

The returned error message will mention something like 'lexical error: invalid char in json text.'.

These diffs seem to make it work for me:

diff --git a/src/cisco_gnmi/xr.py b/src/cisco_gnmi/xr.py
index c55d6e4..50f4240 100644
--- a/src/cisco_gnmi/xr.py
+++ b/src/cisco_gnmi/xr.py
@@ -352,7 +352,13 @@ class XRClient(Client):
                 # module name
                 origin, xpath = xpath.split(":", 1)
                 origin = origin.strip("/")
-        return super(XRClient, cls).parse_xpath_to_gnmi_path(xpath, origin)
+        path = super(XRClient, cls).parse_xpath_to_gnmi_path(xpath, origin)
+        # Need to have double quotes around key value in IOS-XR (CSCvk26949)
+        for elem in path.elem:
+            if elem.key:
+                for key in list(elem.key.keys()):
+                    elem.key[key] = '"{}"'.format(elem.key[key])
+        return path

     @classmethod
     def parse_cli_to_gnmi_path(cls, command):