From 25a94320ecc2432cc3ea58a341a44755b364b0ff Mon Sep 17 00:00:00 2001
From: Tobias Lindberg <tobias.ehlert@gmail.com>
Date: Fri, 12 Feb 2021 17:29:05 +0100
Subject: [PATCH] adding support for null/nil

---
 src/NullSupport.go | 79 ++++++++++++++++++++++++++++++++++++++++++++++
 src/webserver.go   | 12 +++++++
 2 files changed, 91 insertions(+)
 create mode 100644 src/NullSupport.go

diff --git a/src/NullSupport.go b/src/NullSupport.go
new file mode 100644
index 0000000..b0506e8
--- /dev/null
+++ b/src/NullSupport.go
@@ -0,0 +1,79 @@
+package main
+
+// based on Gist:
+//   https://gist.github.com/rsudip90/022c4ef5d98130a224c9239e0a1ab397
+
+import (
+	"database/sql"
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"github.com/go-sql-driver/mysql"
+)
+
+// NullInt64 is an alias for sql.NullInt64 data type
+type NullInt64 struct {
+	sql.NullInt64
+}
+
+// MarshalJSON for NullInt64
+func (ni *NullInt64) MarshalJSON() ([]byte, error) {
+	if !ni.Valid {
+		return []byte("null"), nil
+	}
+	return json.Marshal(ni.Int64)
+}
+
+// NullBool is an alias for sql.NullBool data type
+type NullBool struct {
+	sql.NullBool
+}
+
+// MarshalJSON for NullBool
+func (nb *NullBool) MarshalJSON() ([]byte, error) {
+	if !nb.Valid {
+		return []byte("null"), nil
+	}
+	return json.Marshal(nb.Bool)
+}
+
+// NullFloat64 is an alias for sql.NullFloat64 data type
+type NullFloat64 struct {
+	sql.NullFloat64
+}
+
+// MarshalJSON for NullFloat64
+func (nf *NullFloat64) MarshalJSON() ([]byte, error) {
+	if !nf.Valid {
+		return []byte("null"), nil
+	}
+	return json.Marshal(nf.Float64)
+}
+
+// NullString is an alias for sql.NullString data type
+type NullString struct {
+	sql.NullString
+}
+
+// MarshalJSON for NullString
+func (ns *NullString) MarshalJSON() ([]byte, error) {
+	if !ns.Valid {
+		return []byte("null"), nil
+	}
+	return json.Marshal(ns.String)
+}
+
+// NullTime is an alias for mysql.NullTime data type
+type NullTime struct {
+	mysql.NullTime
+}
+
+// MarshalJSON for NullTime
+func (nt *NullTime) MarshalJSON() ([]byte, error) {
+	if !nt.Valid {
+		return []byte("null"), nil
+	}
+	val := fmt.Sprintf("\"%s\"", nt.Time.Format(time.RFC3339))
+	return []byte(val), nil
+}
diff --git a/src/webserver.go b/src/webserver.go
index 2948a7e..63588bc 100644
--- a/src/webserver.go
+++ b/src/webserver.go
@@ -6,6 +6,7 @@ import (
 	"log"
 	"net/http"
 	"os"
+	"reflect"
 	"strconv"
 	"time"
 
@@ -176,6 +177,17 @@ func getTimeInTimeZone(datestring string) string {
 	return ReturnDate
 }
 
+func isNil(i interface{}) bool {
+	if i == nil {
+		return true
+	}
+	switch reflect.TypeOf(i).Kind() {
+	case reflect.Ptr, reflect.Map, reflect.Array, reflect.Chan, reflect.Slice:
+		return reflect.ValueOf(i).IsNil()
+	}
+	return false
+}
+
 // getEnv func - read an environment or return a default value
 func getEnv(key string, defaultVal string) string {
 	if value, exists := os.LookupEnv(key); exists {