diff --git a/app/config/config.go b/app/config/config.go
index b92dfbc..2ffbe11 100644
--- a/app/config/config.go
+++ b/app/config/config.go
@@ -13,6 +13,7 @@ var (
 	APP_PORT       = ""
 	APP_HOST       = ""
 	APP_HOST_FULL  = ""
+	APP_URL        = ""
 	SENTRY_DNS     = ""
 	DB_DRIVE       = "mysql"
 	DB_ADDR        = "%s:%s@tcp(%s:%s)/%s?charset=utf8&parseTime=True&loc=Local"
@@ -53,6 +54,8 @@ func Load(fileEnv string) error {
 
 	APP_HOST_FULL = fmt.Sprintf("%s:%s", APP_HOST, APP_PORT)
 
+	APP_URL = fmt.Sprintf("http://%s", APP_HOST_FULL)
+
 	value, exists = os.LookupEnv("SENTRY_DNS")
 	if value == "" || !exists {
 		return errors.New("not found variable APP_PORT in .env file or variable empty")
diff --git a/app/controllers/auth/sign_up.go b/app/controllers/auth/sign_up.go
index e21794e..3de36a0 100644
--- a/app/controllers/auth/sign_up.go
+++ b/app/controllers/auth/sign_up.go
@@ -78,7 +78,7 @@ func SignUp(c *gin.Context) {
 	}
 
 	go func() {
-		link := fmt.Sprintf("http://%s%s%s", config.APP_HOST_FULL, "/auth/email/verify/", credential.Token)
+		link := fmt.Sprintf("%s%s%s", config.APP_URL, "/auth/email/verify/", credential.Token)
 
 		emailSignUpbody = strings.ReplaceAll(emailSignUpbody, "{{LINK}}", link)
 
diff --git a/app/entities/user.go b/app/entities/user.go
index df94875..a2f01ef 100644
--- a/app/entities/user.go
+++ b/app/entities/user.go
@@ -4,17 +4,19 @@ import (
 	"gotaskapp/app/security"
 	"strings"
 	"time"
+
+	"gopkg.in/guregu/null.v4/zero"
 )
 
 type User struct {
-	ID        uint64    `json:"id,omitempty"`
-	Avatar    string    `json:"avatar,omitempty"`
-	Firstname string    `json:"firstname,omitempty"`
-	Lastname  string    `json:"lastname,omitempty"`
-	Email     string    `json:"email,omitempty"`
-	Password  string    `json:"-"`
-	Verified  string    `json:"verified"`
-	CreateAt  time.Time `json:"-"`
+	ID        uint64      `json:"id,omitempty"`
+	Avatar    zero.String `json:"avatar,omitempty"`
+	Firstname string      `json:"firstname,omitempty"`
+	Lastname  string      `json:"lastname,omitempty"`
+	Email     string      `json:"email,omitempty"`
+	Password  string      `json:"-"`
+	Verified  string      `json:"verified"`
+	CreateAt  time.Time   `json:"-"`
 }
 
 // Convert password to hash
diff --git a/go.mod b/go.mod
index f2d2542..4ed0c5a 100644
--- a/go.mod
+++ b/go.mod
@@ -32,5 +32,6 @@ require (
 	golang.org/x/sys v0.0.0-20220818161305-2296e01440c6 // indirect
 	golang.org/x/text v0.3.7 // indirect
 	google.golang.org/protobuf v1.28.1 // indirect
+	gopkg.in/guregu/null.v4 v4.0.0 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 )
diff --git a/go.sum b/go.sum
index 4c8079b..4151ff6 100644
--- a/go.sum
+++ b/go.sum
@@ -114,6 +114,8 @@ gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
 gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
+gopkg.in/guregu/null.v4 v4.0.0 h1:1Wm3S1WEA2I26Kq+6vcW+w0gcDo44YKYD7YIEJNHDjg=
+gopkg.in/guregu/null.v4 v4.0.0/go.mod h1:YoQhUrADuG3i9WqesrCmpNRwm1ypAgSHYqoOcTu/JrI=
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=