From 55f6336645b3ef0cc16c3cd3df7981d0aa85fb75 Mon Sep 17 00:00:00 2001
From: Pablo Alvarez de Sotomayor Posadillo <ritho@schibsted.com>
Date: Tue, 26 Jun 2018 18:26:33 -0500
Subject: [PATCH 1/4] Add a new Unset function to remove a key from viper.

In some circunstances, you want to remove a key for your config in
viper, so, instead of setting the key value to nil, it's better to
have a new Unset function to remove the key from the inner map.
---
 viper.go | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/viper.go b/viper.go
index 7027715..d9974bc 100644
--- a/viper.go
+++ b/viper.go
@@ -1406,6 +1406,20 @@ func (v *Viper) Set(key string, value interface{}) {
 	deepestMap[lastKey] = value
 }
 
+// Unset deletes a key from Viper.
+// Unset is case-insensitive for a key.
+func Unset(key string) { v.Unset(key, value) }
+func (v *Viper) Unset(key string) {
+	// If alias passed in, then set the proper override
+	key = v.realKey(strings.ToLower(key))
+
+	path := strings.Split(key, v.keyDelim)
+	lastKey := strings.ToLower(path[len(path)-1])
+	deepestMap := deepSearch(v.override, path[0:len(path)-1])
+
+	delete(deepestMap, lastKey)
+}
+
 // ReadInConfig will discover and load the configuration file from disk
 // and key/value stores, searching in one of the defined paths.
 func ReadInConfig() error { return v.ReadInConfig() }

From 244d9523789acf4920885204bd0b60b8860f9300 Mon Sep 17 00:00:00 2001
From: Pablo Alvarez de Sotomayor Posadillo <ritho@schibsted.com>
Date: Tue, 26 Jun 2018 19:42:04 -0500
Subject: [PATCH 2/4] Fix a call to Unset.

---
 viper.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/viper.go b/viper.go
index d9974bc..95ca75b 100644
--- a/viper.go
+++ b/viper.go
@@ -1408,7 +1408,7 @@ func (v *Viper) Set(key string, value interface{}) {
 
 // Unset deletes a key from Viper.
 // Unset is case-insensitive for a key.
-func Unset(key string) { v.Unset(key, value) }
+func Unset(key string) { v.Unset(key) }
 func (v *Viper) Unset(key string) {
 	// If alias passed in, then set the proper override
 	key = v.realKey(strings.ToLower(key))

From 9956d044940deacec5e08dfbadf8e7eea8fdeb44 Mon Sep 17 00:00:00 2001
From: Pablo Alvarez de Sotomayor Posadillo <ritho@schibsted.com>
Date: Tue, 26 Jun 2018 19:42:04 -0500
Subject: [PATCH 3/4] Fix a call to Unset.

---
 viper.go | 1 +
 1 file changed, 1 insertion(+)

diff --git a/viper.go b/viper.go
index 95ca75b..3205b0f 100644
--- a/viper.go
+++ b/viper.go
@@ -1409,6 +1409,7 @@ func (v *Viper) Set(key string, value interface{}) {
 // Unset deletes a key from Viper.
 // Unset is case-insensitive for a key.
 func Unset(key string) { v.Unset(key) }
+
 func (v *Viper) Unset(key string) {
 	// If alias passed in, then set the proper override
 	key = v.realKey(strings.ToLower(key))

From 6b0e9f4bbb75fa2d64041bd1d4331bfb7779ee36 Mon Sep 17 00:00:00 2001
From: Ritho <pablo.alvarez@lana.xyz>
Date: Sun, 21 Feb 2021 21:00:11 +0100
Subject: [PATCH 4/4] Improve unset to delete it from all the config maps and
 from the alias. Add a new test.

---
 viper.go      | 11 +++++++++--
 viper_test.go | 11 +++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/viper.go b/viper.go
index 3205b0f..e8ec2a3 100644
--- a/viper.go
+++ b/viper.go
@@ -1416,9 +1416,16 @@ func (v *Viper) Unset(key string) {
 
 	path := strings.Split(key, v.keyDelim)
 	lastKey := strings.ToLower(path[len(path)-1])
-	deepestMap := deepSearch(v.override, path[0:len(path)-1])
 
-	delete(deepestMap, lastKey)
+	for _, cfgMap := range []map[string]interface{}{
+		v.override, v.config, v.defaults,
+		v.kvstore,
+	} {
+		cfg := deepSearch(cfgMap, path[0:len(path)-1])
+		delete(cfg, lastKey)
+	}
+
+	delete(v.aliases, key)
 }
 
 // ReadInConfig will discover and load the configuration file from disk
diff --git a/viper_test.go b/viper_test.go
index 45bf8e9..da66d5c 100644
--- a/viper_test.go
+++ b/viper_test.go
@@ -406,6 +406,17 @@ func TestOverrides(t *testing.T) {
 	assert.Equal(t, 40, Get("age"))
 }
 
+func TestUnset(t *testing.T) {
+	SetDefault("unset", 20)
+	Set("unset", 10)
+	RegisterAlias("unset_alias", "unset")
+
+	Unset("unset")
+
+	assert.Equal(t, nil, Get("unset"))
+	assert.Equal(t, nil, Get("unset_alias"))
+}
+
 func TestDefaultPost(t *testing.T) {
 	assert.NotEqual(t, "NYC", Get("state"))
 	SetDefault("state", "NYC")