From aa006507c48ac734fd09d524d0c84736b0147338 Mon Sep 17 00:00:00 2001
From: Nadja Reitzenstein <me@dequbed.space>
Date: Fri, 22 Apr 2022 19:32:17 +0200
Subject: [PATCH] return Optional value for searches

---
 general.capnp       | 9 ++++++++-
 machinesystem.capnp | 5 +++--
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/general.capnp b/general.capnp
index 8a0d470..01460cc 100644
--- a/general.capnp
+++ b/general.capnp
@@ -25,4 +25,11 @@ struct UUID {
 struct KeyValuePair {
     key @0 :Text;
     value @1 :Text;
-}
\ No newline at end of file
+}
+
+struct Optional(T) {
+    union {
+        nothing @0 :Void;
+        just @1 :T;
+    }
+}
diff --git a/machinesystem.capnp b/machinesystem.capnp
index 0ea8cf8..2cb3c2a 100644
--- a/machinesystem.capnp
+++ b/machinesystem.capnp
@@ -7,6 +7,7 @@ using CSharp = import "programming_language/csharp.capnp";
 $CSharp.namespace("FabAccessAPI.Schema");
 
 using General = import "general.capnp";
+using Optional = General.Optional;
 using Machine = import "machine.capnp".Machine;
 
 struct MachineSystem
@@ -15,7 +16,7 @@ struct MachineSystem
     interface Info $CSharp.name("InfoInterface") {
     	getMachineList @0 () -> ( machine_list :List(Machine) );
 
-    	getMachine @1 ( id :Text ) -> Machine;
-		getMachineURN @2 ( urn :Text ) -> Machine;
+    	getMachine @1 ( id :Text ) -> Optional(Machine);
+		getMachineURN @2 ( urn :Text ) -> Optional(Machine);
 	}
 }