VOL-1255: Fixed an issue with the proxy implementation

- Had to change the model slightly to mimic a polymorphic behaviour

Change-Id: I12017cdfedf5c0ed05243245aa2a811556222e0f
diff --git a/db/model/child_type.go b/db/model/child_type.go
index 13b0245..de2fad7 100644
--- a/db/model/child_type.go
+++ b/db/model/child_type.go
@@ -88,15 +88,24 @@
 								return s
 							}
 						case "int32":
-							fallthrough
+							keyFromStr = func(s string) interface{} {
+								i, _ := strconv.Atoi(s)
+								return int32(i)
+							}
 						case "int64":
-							fallthrough
+							keyFromStr = func(s string) interface{} {
+								i, _ := strconv.Atoi(s)
+								return int64(i)
+							}
 						case "uint32":
-							fallthrough
+							keyFromStr = func(s string) interface{} {
+								i, _ := strconv.Atoi(s)
+								return uint32(i)
+							}
 						case "uint64":
 							keyFromStr = func(s string) interface{} {
 								i, _ := strconv.Atoi(s)
-								return i
+								return uint64(i)
 							}
 						default:
 							fmt.Errorf("Key type not implemented - type: %s\n", keyType.(reflect.Type))