/dev/api: Use "fullname" instead of "id" where appropriate.

ID is used elsewhere to mean the raw numerical ID (usually represented
in decimal) rather than the fullname which includes the type ID and is
in base36.

r2/r2/controllers/validator/validator.py

@@ -617,6 +617,7 @@ class VByName(Validator):
         # Limit param only applies when multiple is True
         if not multiple and limit is not None:
             raise TypeError('multiple must be True when limit is set')
+        self.thing_cls = thing_cls
         self.re = fullname_regex(thing_cls)
         self.multiple = multiple
         self.limit = limit
@@ -653,8 +654,9 @@ class VByName(Validator):
         return self.set_error(self._error)
 
     def param_docs(self):
+        thingtype = (self.thing_cls or Thing).__name__.lower()
         return {
-            self.param: 'an existing thing id',
+            self.param: "fullname of a %s" % thingtype,
         }
 
 class VByNameIfAuthor(VByName):
@@ -897,7 +899,7 @@ class VSubmitParent(VByName):
 
     def param_docs(self):
         return {
-            self.param[0]: 'id of a parent thing',
+            self.param[0]: "fullname of parent thing",
         }
 
 class VSubmitSR(Validator):