diff -r 6eede6088d41 -r 3f30adba1c63 src/main/kotlin/de/uapcore/lightpit/entities/User.kt
--- a/src/main/kotlin/de/uapcore/lightpit/entities/User.kt	Sun Dec 20 11:06:25 2020 +0100
+++ b/src/main/kotlin/de/uapcore/lightpit/entities/User.kt	Mon Dec 21 18:29:34 2020 +0100
@@ -25,16 +25,17 @@
 
 package de.uapcore.lightpit.entities
 
-data class User(val id: Int) {
-    var username = ""
-    var mail = ""
-    var givenname = ""
-    var lastname = ""
+data class User(override val id: Int) : Entity {
+    var username: String = ""
+    var mail: String? = null
+    var givenname: String? = null
+    var lastname: String? = null
 
-    val shortDisplayname: String get() {
-        val str = "$givenname $lastname"
-        return if (str.isBlank()) username else str.trim()
-    }
+    val shortDisplayname: String
+        get() {
+            val str = "${givenname ?: ""} ${lastname ?: ""}"
+            return if (str.isBlank()) username else str.trim()
+        }
 
-    val displayname: String get() = if (mail.isBlank()) shortDisplayname else "$shortDisplayname <$mail>"
+    val displayname: String get() = if (mail.isNullOrBlank()) shortDisplayname else "$shortDisplayname <$mail>"
 }
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