Fix sending notifications to users if the user object didn't have an email

pkg/notifications/mail.go

@@ -32,9 +32,7 @@ type Mail struct {
 
 // NewMail creates a new mail object with a default greeting
 func NewMail() *Mail {
-	return &Mail{
+	return &Mail{}
-		greeting: "Hi,",
-	}
 }
 
 // From sets the from name and email address

pkg/notifications/notification.go

@@ -32,7 +32,7 @@ type Notification interface {
 // Notifiable is an entity which can be notified. Usually a user.
 type Notifiable interface {
 	// Should return the email address this notifiable has.
-	RouteForMail() string
+	RouteForMail() (string, error)
 	// Should return the id of the notifiable entity
 	RouteForDB() int64
 }
@@ -73,7 +73,11 @@ func notifyMail(notifiable Notifiable, notification Notification) error {
 		return nil
 	}
 
-	mail.To(notifiable.RouteForMail())
+	to, err := notifiable.RouteForMail()
+	if err != nil {
+		return err
+	}
+	mail.To(to)
 
 	return SendMail(mail)
 }

pkg/user/user.go

@@ -17,6 +17,7 @@
 package user
 
 import (
+	"code.vikunja.io/api/pkg/db"
 	"errors"
 	"fmt"
 	"reflect"
@@ -75,8 +76,19 @@ type User struct {
 }
 
 // RouteForMail routes all notifications for a user to its email address
-func (u *User) RouteForMail() string {
+func (u *User) RouteForMail() (string, error) {
-	return u.Email
+
+	if u.Email == "" {
+		s := db.NewSession()
+		defer s.Close()
+		user, err := getUser(s, &User{ID: u.ID}, true)
+		if err != nil {
+			return "", err
+		}
+		return user.Email, nil
+	}
+
+	return u.Email, nil
 }
 
 // RouteForDB routes all notifications for a user to their id