3 files changed, 20 insertions, 1 deletions
diff --git a/modules/optional/option.go b/modules/optional/option.go
index ccbad259c2..cbecf86987 100644
--- a/modules/optional/option.go
+++ b/modules/optional/option.go
@@ -5,6 +5,12 @@ package optional
 
 import "strconv"
 
+// Option is a generic type that can hold a value of type T or be empty (None).
+//
+// It must use the slice type to work with "chi" form values binding:
+// * non-existing value are represented as an empty slice (None)
+// * existing value is represented as a slice with one element (Some)
+// * multiple values are represented as a slice with multiple elements (Some), the Value is the first element (not well-defined in this case)
 type Option[T any] []T
 
 func None[T any]() Option[T] {
@@ -22,6 +28,13 @@ func FromPtr[T any](v *T) Option[T] {
 	return Some(*v)
 }
 
+func FromMapLookup[K comparable, V any](m map[K]V, k K) Option[V] {
+	if v, ok := m[k]; ok {
+		return Some(v)
+	}
+	return None[V]()
+}
+
 func FromNonDefault[T comparable](v T) Option[T] {
 	var zero T
 	if v == zero {
diff --git a/modules/optional/option_test.go b/modules/optional/option_test.go
index f600ff5a2c..ea80a2e3cb 100644
--- a/modules/optional/option_test.go
+++ b/modules/optional/option_test.go
@@ -56,6 +56,12 @@ func TestOption(t *testing.T) {
 	opt3 := optional.FromNonDefault(1)
 	assert.True(t, opt3.Has())
 	assert.Equal(t, int(1), opt3.Value())
+
+	opt4 := optional.FromMapLookup(map[string]int{"a": 1}, "a")
+	assert.True(t, opt4.Has())
+	assert.Equal(t, 1, opt4.Value())
+	opt4 = optional.FromMapLookup(map[string]int{"a": 1}, "b")
+	assert.False(t, opt4.Has())
 }
 
 func Test_ParseBool(t *testing.T) {
diff --git a/modules/optional/serialization_test.go b/modules/optional/serialization_test.go
index 21d3ad8470..cf81a94cfc 100644
--- a/modules/optional/serialization_test.go
+++ b/modules/optional/serialization_test.go
@@ -4,7 +4,7 @@
 package optional_test
 
 import (
-	std_json "encoding/json" //nolint:depguard
+	std_json "encoding/json" //nolint:depguard // for testing purpose
 	"testing"
 
 	"code.gitea.io/gitea/modules/json"