add service call prototype completer

Signed-off-by: artivis <jeremie.deray@canonical.com>

ros2service/ros2service/api/__init__.py

@@ -15,6 +15,9 @@
 from rclpy.topic_or_service_is_hidden import topic_or_service_is_hidden
 from ros2cli.node.strategy import NodeStrategy
 from ros2srv.api import service_type_completer
+from rosidl_parser.definition import NamespacedType
+from rosidl_runtime_py.convert import message_to_yaml
+from rosidl_runtime_py.import_message import import_message_from_namespaced_type
 
 
 def get_service_names_and_types(*, node, include_hidden_services=False):
@@ -62,3 +65,23 @@ def __call__(self, prefix, parsed_args, **kwargs):
                     if n == service_name:
                         return t
         return service_type_completer()
+
+
+class ServicePrototypeCompleter:
+    """Callable returning a service prototype."""
+
+    def __init__(self, *, service_type_key=None):
+        self.service_type_key = service_type_key
+
+    def __call__(self, prefix, parsed_args, **kwargs):
+        full_service_type = getattr(parsed_args, self.service_type_key)
+        try:
+            parts = full_service_type.split('/')
+            package_name = parts[0]
+            interface_type = parts[1]
+            service_type = parts[-1]
+        except LookupError:
+            return None
+        service = import_message_from_namespaced_type(
+            NamespacedType([package_name, interface_type], service_type))
+        return [message_to_yaml(service.Request())]

ros2service/ros2service/verb/call.py

@@ -19,6 +19,7 @@
 from ros2cli.node import NODE_NAME_PREFIX
 from ros2service.api import ServiceNameCompleter
 from ros2service.api import ServiceTypeCompleter
+from ros2service.api import ServicePrototypeCompleter
 from ros2service.verb import VerbExtension
 from rosidl_runtime_py import set_message_fields
 import yaml
@@ -38,11 +39,13 @@ def add_arguments(self, parser, cli_name):
             help="Type of the ROS service (e.g. 'std_srvs/srv/Empty')")
         arg.completer = ServiceTypeCompleter(
             service_name_key='service_name')
-        parser.add_argument(
+        arg = parser.add_argument(
             'values', nargs='?', default='{}',
             help='Values to fill the service request with in YAML format ' +
                  '(e.g. "{a: 1, b: 2}"), ' +
                  'otherwise the service request will be published with default values')
+        arg.completer = ServicePrototypeCompleter(
+            service_type_key='service_type')
         parser.add_argument(
             '-r', '--rate', metavar='N', type=float,
             help='Repeat the call at a specific rate in Hz')