Do not require ComboBoxes to be valid if they are not required

Elwig/Helpers/AppDbContext.cs

@@ -13,7 +13,8 @@ namespace Elwig.Helpers {
         public DbSet<AT_Gem> Gemeinden { get; set; }
         public DbSet<AT_Kg> Katastralgemeinden { get; set; }
         public DbSet<AT_Ort> Orte { get; set; }
-        public DbSet<AT_PlzDest> Postleitzahlen { get; set; }
+        public DbSet<AT_Plz> Postleitzahlen { get; set; }
+        public DbSet<AT_PlzDest> PlzDestinations { get; set; }
         public DbSet<PostalDest> PostalDestinations { get; set; }
         public DbSet<Branch> Branches { get; set; }
         public DbSet<WbKg> WbKgs { get; set; }

Elwig/Windows/AdministrationWindow.cs

@@ -1,15 +1,13 @@
 using Elwig.Helpers;
-using Elwig.Models;
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Controls;
 
 namespace Elwig.Windows {
     public abstract class AdministrationWindow : ContextWindow {
+
         protected Control[] ExemptInputs { private get; set; }
         protected Control[] RequiredInputs { private get; set; }
         private TextBox[] TextBoxInputs;
@@ -66,14 +64,10 @@ namespace Elwig.Windows {
                 if (input is TextBox tb && tb.Text.Length == 0) {
                     Utils.SetInputInvalid(input);
                     Valid[input] = false;
-                } else if (input is ComboBox cb && cb.SelectedItem == null) {
+                } else if (input is ComboBox cb && cb.SelectedItem == null && cb.ItemsSource != null) {
                     Utils.SetInputInvalid(input);
                 }
             }
-            foreach (var cb in ComboBoxInputs) {
-                if (cb.ItemsSource != null && cb.SelectedItem == null)
-                    Utils.SetInputInvalid(cb);
-            }
         }
 
         protected void LockInputs() {
@@ -155,8 +149,7 @@ namespace Elwig.Windows {
 
         protected void UpdatePlz(TextBox plzInput, ComboBox ortInput) {
             if (plzInput.Text.Length == 4) {
-                int plz = int.Parse(plzInput.Text);
-                ortInput.ItemsSource = Context.Postleitzahlen.Where(p => p.Plz == plz).ToHashSet();
+                ortInput.ItemsSource = Context.Postleitzahlen.Find(int.Parse(plzInput.Text))?.Orte.ToList();
             } else {
                 ortInput.ItemsSource = null;
             }

Elwig/Windows/ContextWindow.cs

@@ -1,14 +1,10 @@
 using Elwig.Helpers;
-using System;
-using System.Collections.Generic;
 using System.ComponentModel;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 using System.Windows;
 
 namespace Elwig.Windows {
     public abstract class ContextWindow : Window {
+
         protected readonly AppDbContext Context;
 
         public ContextWindow() : base() {

Elwig/Windows/MemberAdminWindow.xaml.cs

@@ -1,7 +1,6 @@
 using Microsoft.EntityFrameworkCore;
 using System;
 using System.Collections.Generic;
-using System.ComponentModel;
 using System.Linq;
 using System.Windows;
 using System.Windows.Controls;
@@ -29,7 +28,7 @@ namespace Elwig.Windows {
             };
             RequiredInputs = new Control[] {
                 MgNrInput, GivenNameInput, FamilyNameInput,
-                AddressInput, PlzInput,
+                AddressInput, PlzInput, OrtInput, BillingOrtInput,
                 BusinessSharesInput, BranchInput, DefaultKgInput
             };
         }