From 78ada3fc29b7dd4a76156bb9937ea3ec4d6b2c25 Mon Sep 17 00:00:00 2001
From: Kiril Vladimiroff <kiril@vladimiroff.org>
Date: Thu, 5 Mar 2020 16:18:52 +0200
Subject: [PATCH] Implement Scan with a type switch

This is just a minor (and a bit opinionated) tweak in Scan. While using
the generated Scan method, realized that what's being returned from any
driver I've stumbled upon is actually []byte instead of string, thus
always causing a one failed type assertion on Scan.
---
 golden_test.go | 36 ++++++++++++++++++++----------------
 sql.go         | 20 +++++++++++---------
 2 files changed, 31 insertions(+), 25 deletions(-)

diff --git a/golden_test.go b/golden_test.go
index 9f0b5b5..040fa68 100644
--- a/golden_test.go
+++ b/golden_test.go
@@ -1682,14 +1682,16 @@ func (i *Prime) Scan(value interface{}) error {
 		return nil
 	}
 
-	str, ok := value.(string)
-	if !ok {
-		bytes, ok := value.([]byte)
-		if !ok {
-			return fmt.Errorf("value is not a byte slice")
-		}
-
-		str = string(bytes[:])
+	var str string
+	switch v := value.(type) {
+	case []byte:
+		str = string(b)
+	case string:
+		str = v
+	case fmt.Stringer:
+		str = v.String()
+	default:
+		return fmt.Errorf("invalid value of Prime: %[1]T(%[1]v)", value)
 	}
 
 	val, err := PrimeString(str)
@@ -1867,14 +1869,16 @@ func (i *Prime) Scan(value interface{}) error {
 		return nil
 	}
 
-	str, ok := value.(string)
-	if !ok {
-		bytes, ok := value.([]byte)
-		if !ok {
-			return fmt.Errorf("value is not a byte slice")
-		}
-
-		str = string(bytes[:])
+	var str string
+	switch v := value.(type) {
+	case []byte:
+		str = string(b)
+	case string:
+		str = v
+	case fmt.Stringer:
+		str = v.String()
+	default:
+		return fmt.Errorf("invalid value of Prime: %[1]T(%[1]v)", value)
 	}
 
 	val, err := PrimeString(str)
diff --git a/sql.go b/sql.go
index 67d5354..2a2906f 100644
--- a/sql.go
+++ b/sql.go
@@ -12,21 +12,23 @@ const scanMethod = `func (i *%[1]s) Scan(value interface{}) error {
 		return nil
 	}
 
-	str, ok := value.(string)
-	if !ok {
-		bytes, ok := value.([]byte)
-		if !ok {
-			return fmt.Errorf("value is not a byte slice")
-		}
-
-		str = string(bytes[:])
+	var str string
+	switch v := value.(type) {
+	case []byte:
+		str = string(b)
+	case string:
+		str = v
+	case fmt.Stringer:
+		str = v.String()
+	default:
+		return fmt.Errorf("invalid value of %[1]s: %%[1]T(%%[1]v)", value)
 	}
 
 	val, err := %[1]sString(str)
 	if err != nil {
 		return err
 	}
-	
+
 	*i = val
 	return nil
 }