给变量添加Mqtt服务器的功能

ViewModels/Dialogs/MqttSelectionDialogViewModel.cs

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+using System.Collections.ObjectModel;
+using CommunityToolkit.Mvvm.ComponentModel;
+using PMSWPF.Models;
+using PMSWPF.Data.Repositories;
+using System.Threading.Tasks;
+
+namespace PMSWPF.ViewModels.Dialogs;
+
+public partial class MqttSelectionDialogViewModel : ObservableObject
+{
+    private readonly MqttRepository _mqttRepository;
+
+    [ObservableProperty]
+    private ObservableCollection<Mqtt> mqtts;
+
+    [ObservableProperty]
+    private Mqtt? selectedMqtt;
+
+    public MqttSelectionDialogViewModel()
+    {
+        _mqttRepository = new MqttRepository();
+        LoadMqtts();
+    }
+
+    private async void LoadMqtts()
+    {
+        try
+        {
+            var allMqtts = await _mqttRepository.GetAll();
+            Mqtts = new ObservableCollection<Mqtt>(allMqtts);
+        }
+        catch (Exception ex)
+        {
+            // 这里需要一个日志记录器，但由于ViewModel中没有直接注入ILogger，
+            // 暂时使用Console.WriteLine或NotificationHelper
+            // 更好的做法是注入ILogger或使用静态日志类
+            Console.WriteLine($"加载MQTT服务器列表失败: {ex.Message}");
+            // 或者使用NotificationHelper.ShowMessage("加载MQTT服务器列表失败", NotificationType.Error);
+        }
+    }
+}