code(pkg/references) - provide more flexible references

README.md

@@ -1095,7 +1095,7 @@ type Reference struct {
 ```
 
 - [ModelField](#model-field) - is embedded struct, you can use same fields
-- Expire[sec] - duration when reference is expired after fetching (0 means no expired)
+- Expire[sec] - duration when reference is expired after fetching. Not set => **forever cached**. Set to 0 => **every time re-fetch**. Set to n > 0 => **cached for n second** 
 
 For [Fitter](#how-to-use-fitter)
 ```go

pkg/config/config.go

@@ -24,7 +24,7 @@ type RefMap map[string]*Reference
 type Reference struct {
 	*ModelField
 
-	Expire uint32 `yaml:"expire" json:"expire"`
+	Expire *uint32 `yaml:"expire" json:"expire"`
 }
 
 type Limits struct {

pkg/references/references.go

@@ -36,13 +36,18 @@ func getValueFromFetcher(fetcher refFetcher, name string, cfg *config.ModelField
 	return res
 }
 
-func getExpireTime(expire uint32) *time.Time {
-	if expire > 0 {
-		expireTime := time.Now().Add(time.Nanosecond * time.Duration(expire))
+func getExpireTime(expire *uint32) *time.Time {
+	if expire == nil {
+		return nil
+	}
+
+	if *expire > 0 {
+		expireTime := time.Now().Add(time.Nanosecond * time.Duration(*expire))
 		return &expireTime
 	}
 
-	return nil
+	zero := time.Time{}
+	return &zero
 }
 
 func Get(name string) builder.Jsonable {