当我使用实体框架更改对象时，为什么 ListView 没有更改？

Question

我有两个具有一对多关系的相关对象。更改其中一项的值时，我看到 observablecollection 中的值已更改，但 ListView 中没有任何更改。当您添加和删除对 ListView 的更改时会显示。 第一个模型：

public partial class device_categories
{
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
    public device_categories()
    {
        this.devices = new HashSet<device>();
    }

    public int device_category_id { get; set; }
    public string category_name { get; set; }
    public int device_complexity_id { get; set; }

    public virtual device_complexities device_complexities { get; set; }
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<device> devices { get; set; }
}

第二个模型：

public partial class device_complexities
{
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
    public device_complexities()
    {
        this.device_categories = new HashSet<device_categories>();
    }

    public int device_complexity_id { get; set; }
    public string device_complexity_name { get; set; }

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<device_categories> device_categories { get; set; }
}

视图模型：

class DeviceCategoriesViewModel
{
    newtechd dc = new newtechd();
    public DeviceCategoriesViewModel()
    {
        dc.device_categories.Include(com => com.device_complexities).Load();
        dc.device_complexities.Load();
        DeviceCategories = dc.device_categories.Local;
        DeviceComplexities = dc.device_complexities.Local;
    }
    // Create Collection of DeviceCategories
    private ObservableCollection<device_categories> deviceCategories;
    public ObservableCollection<device_categories> DeviceCategories
    {
        get
        {
            return deviceCategories;
        }

        set
        {
            deviceCategories = value;
        }
    }
    // Create Collection of Device Complexity (used in comboBox)
    private ObservableCollection<device_complexities> deviceComplexities;
    public ObservableCollection<device_complexities> DeviceComplexities
    {
        get
        {
            return deviceComplexities;
        }

        set
        {
            deviceComplexities = value;
        }
    }

    private device_complexities selectedDeviceComplexity;
    public device_complexities SelectedDeviceComplexity
    {
        get
        {
            return selectedDeviceComplexity;
        }

        set
        {
            selectedDeviceComplexity = value;
        }
    }

    private device_categories selectedDeviceCategory;
    public device_categories SelectedDeviceСategory
    {
        get
        {
            return selectedDeviceCategory;
        }

        set
        {
            selectedDeviceCategory = value;
        }
    }
    //Insert new Item
    public void AddDevCat(string name)
    {
        string addName = (String)name;

        device_categories add_Device_Categories = new device_categories
        {
            category_name = addName,
            device_complexity_id = selectedDeviceComplexity.device_complexity_id
        };
        dc.device_categories.Add(add_Device_Categories);
        dc.SaveChanges();
    }
    // Modify Item (I think problem somewhere here)
    public void EditDevCat(string newName, int comp_id)
    {
        string newCatName = (String)newName;
        int dev_comp_id = Convert.ToInt32(comp_id);

        device_categories dev_cat_to_edit = selectedDeviceCategory;
        device_complexities new_dev_comp = dc.device_complexities.Find(dev_comp_id);
        dev_cat_to_edit.category_name = newCatName;
        dev_cat_to_edit.device_complexities = new_dev_comp;
        dc.Entry(dev_cat_to_edit).State = EntityState.Modified;
        dc.SaveChanges();
    }
}

XAML

<ListView x:Name="deviceCategoriesLV" HorizontalAlignment="Right" MaxHeight="200" MinHeight="150"  Margin="0,15,411.6,0" Grid.Column="0" ItemsSource="{Binding DeviceCategories}" SelectedItem="{Binding SelectedDeviceСategory}" VerticalAlignment="Top" Width="372" Height="226">
        <ListBox.ContextMenu>
            <ContextMenu>
                <MenuItem Header="Удалить" x:Name="deleteDeviceCategory" Click="DeleteDeviceCategory_Click"/>
            </ContextMenu>
        </ListBox.ContextMenu>
        <ListView.ItemTemplate>
            <DataTemplate>
                <StackPanel Margin="5">
                    <TextBlock FontSize="14" Text="{Binding Path=category_name}" />
                    <TextBlock Text="{Binding Path=device_complexities.device_complexity_name}" />
                    <!--<TextBlock FontSize="18" Text="{Binding Path=Brand_name}" />-->
                </StackPanel>
            </DataTemplate>
        </ListView.ItemTemplate>
    </ListView>

点击更改按钮后，我看到 ComboBox 和 TextBox 发生了变化

Answer 1

我相信这是该线程的副本。简短的版本是您的 device_complexities 类需要实现 IPropertyChanged。

ObservableCollection and Item PropertyChanged