From 08d14d201de3053667971f9652f3c000582930c3 Mon Sep 17 00:00:00 2001
From: mtsoltan <mt@soltan.rs>
Date: Sun, 14 Jul 2024 16:48:14 +0900
Subject: [PATCH] Fix option to handle type conversion.

---
 .gitignore     |  1 +
 option.go      | 12 +++++++++++-
 option_test.go | 30 ++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/.gitignore b/.gitignore
index 3aa3a0a..7b9b3e7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -34,3 +34,4 @@ go.work
 cover.out
 cover.html
 .vscode
+.idea
\ No newline at end of file
diff --git a/option.go b/option.go
index 9955094..5212556 100644
--- a/option.go
+++ b/option.go
@@ -297,6 +297,16 @@ func (o *Option[T]) Scan(src any) error {
 		}
 	}
 
+	// we try to convertAssign values that we can't directly assign because ConvertValue
+	// will return immediately for v that is already a Value, even if it is a different
+	// Value type than the one we expect here.
+	var st sql.Null[T]
+	if err := st.Scan(src); err == nil {
+		o.isPresent = true
+		o.value = st.V
+		return nil
+	}
+
 	return fmt.Errorf("failed to scan Option[T]")
 }
 
@@ -306,7 +316,7 @@ func (o Option[T]) Value() (driver.Value, error) {
 		return nil, nil
 	}
 
-	return o.value, nil
+	return driver.DefaultParameterConverter.ConvertValue(o.value)
 }
 
 // leftValue returns an error if the Option is None, otherwise nil
diff --git a/option_test.go b/option_test.go
index 55835ea..0969f8b 100644
--- a/option_test.go
+++ b/option_test.go
@@ -407,6 +407,25 @@ func TestOptionScan(t *testing.T) {
 	is.Equal(err2Exp, err2)
 }
 
+func TestOptionScanWithPossibleConvert(t *testing.T) {
+	is := assert.New(t)
+
+	// As passed by the sql package in some cases, src is a []byte.
+	// https://github.com/golang/go/blob/071b8d51c1a70fa6b12f0bed2e93370e193333fd/src/database/sql/convert.go#L396
+	src1 := []byte{65, 66, 67}
+	dest1 := None[string]()
+	src2 := int32(32)
+	dest2 := None[int]()
+
+	err1 := dest1.Scan(src1)
+	err2 := dest2.Scan(src2)
+
+	is.Nil(err1)
+	is.Equal(Some("ABC"), dest1)
+	is.Nil(err2)
+	is.Equal(Some(32), dest2)
+}
+
 func TestOptionValue(t *testing.T) {
 	is := assert.New(t)
 
@@ -425,6 +444,17 @@ func TestOptionValue(t *testing.T) {
 	is.Nil(err2)
 }
 
+func TestOptionValueWithPossibleConvert(t *testing.T) {
+	is := assert.New(t)
+
+	opt := Some(uint32(42))
+	expected := int64(42)
+
+	value, err := opt.Value()
+	is.Nil(err)
+	is.Equal(expected, value)
+}
+
 type SomeScanner struct {
 	Cool bool
 	Some int