From a33304548a947d18a1ed73adfd8c618aabf1a762 Mon Sep 17 00:00:00 2001
From: Charles Iliya Krempeaux <iamreiver@gmail.com>
Date: Sat, 23 Sep 2023 07:36:42 +0900
Subject: [PATCH] opt.Optional[string].MarshalJSON()

---
 optional.go | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/optional.go b/optional.go
index e46dafc..530d16e 100644
--- a/optional.go
+++ b/optional.go
@@ -2,6 +2,7 @@ package opt
 
 import (
 	"fmt"
+	"encoding/json"
 )
 
 // Optional represents an optional value.
@@ -169,6 +170,15 @@ func (receiver Optional[T]) GoString() string {
 	return fmt.Sprintf("opt.Something[%T](%#v)", receiver.value, receiver.value)
 }
 
+// MarshalJSON makes it so json.Marshaler is implemented.
+func (receiver Optional[string]) MarshalJSON() ([]byte, error) {
+	if !receiver.something {
+		return nil, fmt.Errorf("cannot marshal opt.Nothing[%T]()", receiver.value)
+	}
+
+	return json.Marshal(receiver.value)
+}
+
 // WhenNothing will call ‘fn’ when ‘receiver’ is holding nothing.
 //
 // It will not call ‘fn’ when ‘receier’ is hold something.