From 9383b28a065fae953d15e2dbb867ab3285aaaa50 Mon Sep 17 00:00:00 2001
From: Ruslan Kuprieiev <kupruser@gmail.com>
Date: Fri, 6 Apr 2018 02:45:20 +0300
Subject: [PATCH] dvc: stage: don't write None and empty lists

Fixes #622

Signed-off-by: Ruslan Kuprieiev <kupruser@gmail.com>
---
 dvc/stage.py | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/dvc/stage.py b/dvc/stage.py
index 3a369ca37..b1ced8427 100644
--- a/dvc/stage.py
+++ b/dvc/stage.py
@@ -161,11 +161,17 @@ class Stage(object):
         deps = [x.dumpd(self.cwd) for x in self.deps]
         outs = [x.dumpd(self.cwd) for x in self.outs]
 
-        return {
-            Stage.PARAM_CMD: self.cmd,
-            Stage.PARAM_DEPS: deps,
-            Stage.PARAM_OUTS: outs,
-        }
+        ret = {}
+        if self.cmd:
+            ret[Stage.PARAM_CMD] = self.cmd
+
+        if len(deps):
+            ret[Stage.PARAM_DEPS] = deps
+
+        if len(outs):
+            ret[Stage.PARAM_OUTS] = outs
+
+        return ret
 
     def dump(self, fname=None):
         if not fname: