From 6a0ecc0fdceac4b1885f5072ae8b8c8aab773103 Mon Sep 17 00:00:00 2001
From: Robert Kopaczewski <rk@23doors.com>
Date: Mon, 17 Aug 2020 21:32:09 +0200
Subject: [PATCH] feat: add store nil option to rediscache

---
 rediscache/cache.go | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/rediscache/cache.go b/rediscache/cache.go
index 54c2346..b6256b0 100644
--- a/rediscache/cache.go
+++ b/rediscache/cache.go
@@ -1,6 +1,7 @@
 package rediscache
 
 import (
+	"errors"
 	"reflect"
 	"time"
 
@@ -16,6 +17,10 @@ const (
 	versionGraceDuration = 5 * time.Minute
 )
 
+var (
+	ErrNil = errors.New("compute returned nil object and storeNil is false")
+)
+
 type Cache struct {
 	codec *cache.Codec
 	db    *database.DB
@@ -27,6 +32,7 @@ type Config struct {
 	CacheTimeout      time.Duration
 	CacheVersion      int
 	ServiceKey        string
+	StoreNil          bool
 }
 
 var DefaultConfig = Config{
@@ -34,6 +40,7 @@ var DefaultConfig = Config{
 	CacheTimeout:      12 * time.Hour,
 	LocalCacheTimeout: 1 * time.Hour,
 	ServiceKey:        "cache",
+	StoreNil:          false,
 }
 
 func WithTimeout(local, global time.Duration) func(*Config) {
@@ -55,6 +62,12 @@ func WithServiceKey(val string) func(*Config) {
 	}
 }
 
+func WithStoreNil(storeNil bool) func(*Config) {
+	return func(config *Config) {
+		config.StoreNil = storeNil
+	}
+}
+
 // Init sets up a cache.
 func New(r rediser, db *database.DB, opts ...func(*Config)) *Cache {
 	cfg := DefaultConfig
@@ -126,6 +139,10 @@ func (c *Cache) VersionedCache(cacheKey, lookup string, val interface{},
 		return err
 	}
 
+	if object == nil && !c.cfg.StoreNil {
+		return ErrNil
+	}
+
 	if version == "" {
 		version, err = c.codec.Redis.Get(versionKeyFunc()).Result()
 		if err != nil && err != redis.Nil {