From 06974cccf72fbb5bd19537b6e1293167a9ed5d62 Mon Sep 17 00:00:00 2001
From: zepatrik <zepatrik@users.noreply.github.com>
Date: Thu, 12 Sep 2024 11:55:37 +0200
Subject: [PATCH 1/2] feat(otelx): nullable attribute helpers

---
 otelx/attribute.go | 43 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/otelx/attribute.go b/otelx/attribute.go
index 61911a1e..8e64f254 100644
--- a/otelx/attribute.go
+++ b/otelx/attribute.go
@@ -3,7 +3,12 @@
 
 package otelx
 
-import "go.opentelemetry.io/otel/attribute"
+import (
+	"database/sql"
+	"fmt"
+
+	"go.opentelemetry.io/otel/attribute"
+)
 
 func StringAttrs(attrs map[string]string) []attribute.KeyValue {
 	s := []attribute.KeyValue{}
@@ -12,3 +17,39 @@ func StringAttrs(attrs map[string]string) []attribute.KeyValue {
 	}
 	return s
 }
+
+func AutoInt[I int | int32 | int64](k string, v I) attribute.KeyValue {
+	// Internally, the OpenTelemetry SDK uses int64 for all integer values anyway.
+	return attribute.Int64(k, int64(v))
+}
+
+func Nullable[V any, VN *V | sql.Null[V], A func(string, V) attribute.KeyValue](a A, k string, v VN) attribute.KeyValue {
+	switch v := any(v).(type) {
+	case *V:
+		if v == nil {
+			return attribute.String(k, "<nil>")
+		}
+		return a(k, *v)
+	case sql.Null[V]:
+		if !v.Valid {
+			return attribute.String(k, "<nil>")
+		}
+		return a(k, v.V)
+	}
+	return attribute.String(k, "unsupported type")
+}
+
+func NullString[V *string | sql.Null[string]](k string, v V) attribute.KeyValue {
+	return Nullable(attribute.String, k, v)
+}
+
+func NullStringer(k string, v fmt.Stringer) attribute.KeyValue {
+	if v == nil {
+		return attribute.String(k, "<nil>")
+	}
+	return attribute.String(k, v.String())
+}
+
+func NullInt[I int | int32 | int64, V *I | sql.Null[I]](k string, v V) attribute.KeyValue {
+	return Nullable[I](AutoInt, k, v)
+}

From 15b0ff4b869c18bfa9555d27d1e4ee091f3f9872 Mon Sep 17 00:00:00 2001
From: zepatrik <zepatrik@users.noreply.github.com>
Date: Thu, 12 Sep 2024 12:00:10 +0200
Subject: [PATCH 2/2] chore: minor improvements

---
 otelx/attribute.go | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/otelx/attribute.go b/otelx/attribute.go
index 8e64f254..81db5b46 100644
--- a/otelx/attribute.go
+++ b/otelx/attribute.go
@@ -10,6 +10,8 @@ import (
 	"go.opentelemetry.io/otel/attribute"
 )
 
+const nullString = "<null>"
+
 func StringAttrs(attrs map[string]string) []attribute.KeyValue {
 	s := []attribute.KeyValue{}
 	for k, v := range attrs {
@@ -27,16 +29,17 @@ func Nullable[V any, VN *V | sql.Null[V], A func(string, V) attribute.KeyValue](
 	switch v := any(v).(type) {
 	case *V:
 		if v == nil {
-			return attribute.String(k, "<nil>")
+			return attribute.String(k, nullString)
 		}
 		return a(k, *v)
 	case sql.Null[V]:
 		if !v.Valid {
-			return attribute.String(k, "<nil>")
+			return attribute.String(k, nullString)
 		}
 		return a(k, v.V)
 	}
-	return attribute.String(k, "unsupported type")
+	// This should never happen, as the type switch above is exhaustive to the generic type VN.
+	return attribute.String(k, fmt.Sprintf("<got unsupported type %T>", v))
 }
 
 func NullString[V *string | sql.Null[string]](k string, v V) attribute.KeyValue {
@@ -45,7 +48,7 @@ func NullString[V *string | sql.Null[string]](k string, v V) attribute.KeyValue
 
 func NullStringer(k string, v fmt.Stringer) attribute.KeyValue {
 	if v == nil {
-		return attribute.String(k, "<nil>")
+		return attribute.String(k, nullString)
 	}
 	return attribute.String(k, v.String())
 }