Run hooks for DisplayCommandBase

Command base class has provisions to run hooks for a command in
its run() method. We need to do the same for the
DisplayCommandBase class since it does not call super().run()

Change-Id: Ic5481523d4bd919fe7fb10e00330dea2ff688ec4

cliff/command.py

@@ -133,12 +133,36 @@ class Command(object):
 
         Return the value returned by :meth:`take_action` or 0.
         """
+        self._run_before_hooks(parsed_args)
+        return_code = self.take_action(parsed_args) or 0
+        self._run_after_hooks(parsed_args, return_code)
+        return return_code
+
+    def _run_before_hooks(self, parsed_args):
+        """Calls before() method of the hooks.
+
+        This method is intended to be called from the run() method before
+        take_action() is called.
+
+        This method should only be overriden by developers creating new
+        command base classes and only if it is necessary to have different
+        hook processing behavior.
+        """
         for hook in self._hooks:
             hook.obj.before(parsed_args)
-        return_code = self.take_action(parsed_args) or 0
+
+    def _run_after_hooks(self, parsed_args, return_code):
+        """Calls after() method of the hooks.
+
+        This method is intended to be called from the run() method after
+        take_action() is called.
+
+        This method should only be overriden by developers creating new
+        command base classes and only if it is necessary to have different
+        hook processing behavior.
+        """
         for hook in self._hooks:
             hook.obj.after(parsed_args, return_code)
-        return return_code
 
 
 class _SmartHelpFormatter(_argparse.HelpFormatter):

cliff/display.py

@@ -108,8 +108,10 @@ class DisplayCommandBase(command.Command):
         return columns_to_include, selector
 
     def run(self, parsed_args):
+        self._run_before_hooks(parsed_args)
         self.formatter = self._formatter_plugins[parsed_args.formatter].obj
         column_names, data = self.take_action(parsed_args)
+        self._run_after_hooks(parsed_args, (column_names, data))
         self.produce_output(parsed_args, column_names, data)
         return 0