如何从视图和MVVM light

Question

我的应用程序有一些工作模式，可以从模型和用户的UI更改。 当我启动应用程序时，它显示默认模式正确（从模型更新数据）。但是当我从UI更改所选项目时，它会显示所选项目一段时间，然后取消选择它（从UI更新，然后从模型更新）。 我在两种情况下划分了更新逻辑 首先，从UI更新应调用模型更新。 第二，从模型更新UI不应调用模型更新。 我的错是什么？ 见下面的代码

查看

            <ComboBox ItemsSource="{Binding AlgorithmCollection}" 
                      SelectedItem="{Binding SelectedAlgorithm, Mode=TwoWay}"
                      Style="{StaticResource AutoOpenComboBoxStyle}" />

视图模型

        private NamedInt _selectedAlgorithm;
        private ObservableCollection<NamedInt> _algorithmCollection;
        public NamedInt SelectedAlgorithm
    {
        get { return this._selectedAlgorithm; }
        set { Set(() => SelectedAlgorithm, ref this._selectedAlgorithm, value);

            if (this._needUpdate && Core.Kernel.Instance.PluginController.ActiveConverter != null &&
                this._selectedAlgorithm != null)
            {
                Core.Kernel.Instance.PluginController.ActiveConverter.SetActiveAlgorithm(this._selectedAlgorithm.Id);
            }
        }
    }

    public ObservableCollection<NamedInt> AlgorithmCollection
    {
        get { return this._algorithmCollection; }
        set { Set(() => AlgorithmCollection, ref this._algorithmCollection, value);
        }
    }

我听模型事件更新ViewModel，当它是必须的时候。在ViewModel的构造函数中

            Messenger.Default.Register<SoftwareSettingsUpdateMessage>(this, ReceiveUpdateMessage);



        private void ReceiveUpdateMessage(SoftwareSettingsUpdateMessage action)
    {
        if (action.SettingType.HasFlag(SoftwareSettingsType.Algorithm))
        {
            RefreshAlgorithms();
        }

        this._needUpdate = true;
    }

    private void RefreshAlgorithms()
    {
        var converter = Core.Kernel.Instance.PluginController.ActiveConverter;

        var algorithms = converter?.Algorithms;
        if (algorithms != null)
        {
            AlgorithmCollection = new ObservableCollection<NamedInt>(
                algorithms.Select((x, index) => new NamedInt(x, index))
            );

            var activeId = converter.ActiveAlgorithmId;
            if (activeId >= 0 && activeId < AlgorithmCollection.Count)
            {
                this._needUpdate = false;
                SelectedAlgorithm = AlgorithmCollection[activeId];
                this._needUpdate = true;
            }
            else
            {
                SelectedAlgorithm = null;
            }
        }
        else
        {
            AlgorithmCollection = new ObservableCollection<NamedInt>();
            SelectedAlgorithm = null;
        }

        IsActive = true;
    }