From 9f43a4a2652482cb0cd9512f4464aebb944a7d83 Mon Sep 17 00:00:00 2001
From: Mike Farah <mike.farah@encapto.com>
Date: Tue, 8 Sep 2020 09:46:04 +1000
Subject: [PATCH] Keep comments when using the write commandt o update values

---
 cmd/utils.go                            |  3 ++-
 cmd/write_test.go                       | 18 ++++++++++++++++++
 pkg/yqlib/lib.go                        |  1 +
 pkg/yqlib/update_navigation_strategy.go |  8 +++++---
 4 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/cmd/utils.go b/cmd/utils.go
index b48a00f3..8696a30b 100644
--- a/cmd/utils.go
+++ b/cmd/utils.go
@@ -511,7 +511,8 @@ func readUpdateCommands(args []string, expectedArgs int, badArgsMessage string)
 		log.Debug("args %v", args)
 		log.Debug("path %v", args[expectedArgs-2])
 		log.Debug("Value %v", args[expectedArgs-1])
-		updateCommands[0] = yqlib.UpdateCommand{Command: "update", Path: args[expectedArgs-2], Value: valueParser.Parse(args[expectedArgs-1], customTag, customStyle, anchorName, makeAlias), Overwrite: true}
+		value := valueParser.Parse(args[expectedArgs-1], customTag, customStyle, anchorName, makeAlias)
+		updateCommands[0] = yqlib.UpdateCommand{Command: "update", Path: args[expectedArgs-2], Value: value, Overwrite: true, DontUpdateComments: true}
 	} else if len(args) == expectedArgs-1 {
 		// don't update the value
 		updateCommands = make([]yqlib.UpdateCommand, 1)
diff --git a/cmd/write_test.go b/cmd/write_test.go
index f653ca3a..8249a890 100644
--- a/cmd/write_test.go
+++ b/cmd/write_test.go
@@ -27,6 +27,24 @@ func TestWriteCmd(t *testing.T) {
 	test.AssertResult(t, expectedOutput, result.Output)
 }
 
+func TestWriteKeepCommentsCmd(t *testing.T) {
+	content := `b:
+  c: 3 # comment
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b.c 7", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 7 # comment
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
 func TestWriteWithTaggedStyleCmd(t *testing.T) {
 	content := `b:
   c: dog
diff --git a/pkg/yqlib/lib.go b/pkg/yqlib/lib.go
index 90682186..60d99fb7 100644
--- a/pkg/yqlib/lib.go
+++ b/pkg/yqlib/lib.go
@@ -18,6 +18,7 @@ type UpdateCommand struct {
 	Value               *yaml.Node
 	Overwrite           bool
 	DontUpdateNodeValue bool
+	DontUpdateComments  bool
 }
 
 func KindString(kind yaml.Kind) string {
diff --git a/pkg/yqlib/update_navigation_strategy.go b/pkg/yqlib/update_navigation_strategy.go
index bfb376e6..4721a26a 100644
--- a/pkg/yqlib/update_navigation_strategy.go
+++ b/pkg/yqlib/update_navigation_strategy.go
@@ -27,9 +27,11 @@ func UpdateNavigationStrategy(updateCommand UpdateCommand, autoCreate bool) Navi
 				node.Content = changesToApply.Content
 				node.Anchor = changesToApply.Anchor
 				node.Alias = changesToApply.Alias
-				node.HeadComment = changesToApply.HeadComment
-				node.LineComment = changesToApply.LineComment
-				node.FootComment = changesToApply.FootComment
+				if !updateCommand.DontUpdateComments {
+					node.HeadComment = changesToApply.HeadComment
+					node.LineComment = changesToApply.LineComment
+					node.FootComment = changesToApply.FootComment
+				}
 			} else {
 				log.Debug("skipping update as node already has value %v and overwriteFlag is ", node.Value, updateCommand.Overwrite)
 			}