From ce5cd898b9eb50dca216e23d84e74c0f12fa2588 Mon Sep 17 00:00:00 2001
From: Max Brosnahan <maximilianbrosnahan@gmail.com>
Date: Wed, 21 May 2025 08:17:15 +0200
Subject: [PATCH] Bind empty strings to nil pointers

This allows pointers to be used for optional values in query, path and
body params.
---
 bind.go      |  4 ++++
 bind_test.go | 31 +++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/bind.go b/bind.go
index 5940e15da..335aaac72 100644
--- a/bind.go
+++ b/bind.go
@@ -357,6 +357,10 @@ func unmarshalInputsToField(valueKind reflect.Kind, values []string, field refle
 
 func unmarshalInputToField(valueKind reflect.Kind, val string, field reflect.Value) (bool, error) {
 	if valueKind == reflect.Ptr {
+		if val == "" {
+			field.Set(reflect.Zero(field.Type()))
+			return true, nil
+		}
 		if field.IsNil() {
 			field.Set(reflect.New(field.Type().Elem()))
 		}
diff --git a/bind_test.go b/bind_test.go
index 303c8854a..790607715 100644
--- a/bind_test.go
+++ b/bind_test.go
@@ -1453,6 +1453,37 @@ func TestBindInt8(t *testing.T) {
 	})
 }
 
+func TestBindPointer(t *testing.T) {
+	t.Run("nok, binding fails", func(t *testing.T) {
+		type target struct {
+			V *time.Time `query:"v"`
+		}
+		p := target{}
+		err := testBindURL("/?v=x", &p)
+		assert.EqualError(t, err, "code=400, message=parsing time \"x\" as \"2006-01-02T15:04:05Z07:00\": cannot parse \"x\" as \"2006\", internal=parsing time \"x\" as \"2006-01-02T15:04:05Z07:00\": cannot parse \"x\" as \"2006\"")
+	})
+
+	t.Run("ok, bind empty value to nil", func(t *testing.T) {
+		type target struct {
+			V *time.Time `query:"v"`
+		}
+		p := target{}
+		err := testBindURL("/?v=", &p)
+		assert.NoError(t, err)
+		assert.Nil(t, p.V)
+	})
+
+	t.Run("ok, binds to provided value", func(t *testing.T) {
+		type target struct {
+			V *time.Time `query:"v"`
+		}
+		p := target{}
+		err := testBindURL("/?v=2006-01-02T15:04:05Z", &p)
+		assert.NoError(t, err)
+		assert.Equal(t, "2006-01-02T15:04:05Z", p.V.Format(time.RFC3339))
+	})
+}
+
 func TestBindMultipartFormFiles(t *testing.T) {
 	file1 := createTestFormFile("file", "file1.txt")
 	file11 := createTestFormFile("file", "file11.txt")