ObservableCollection 不更新 ListView答案

【问题标题】：ObservableCollection doesn't update ListViewObservableCollection 不更新 ListView
【发布时间】：2017-01-21 19:52:00
【问题描述】：

我的 ObservableCollection 列表没有更新视图。我使用 MVVM Light

这是我的虚拟机

public class MainViewModel : ViewModelBase{
public ObservableCollection<ProductModel> Products { get; set; }

private void GetData()
{
    //getting data here

    Products = new ObservableCollection<ProductModel>();

    foreach (var item in myData)
    {
        Products.Add(item);
    }
}}

XAML：

DataContext="{Binding Source={StaticResource Locator}, Path=Main}"><FlowDocumentReader BorderBrush = "Black" BorderThickness="2">
<FlowDocument>
    <BlockUIContainer>
        <ListView BorderThickness = "2" ItemsSource="{Binding Products}">
            <ListView.View>
                <GridView>
                    <GridViewColumn Header = "Lp." DisplayMemberBinding="{Binding Path=OrdinalNumber}" Width="100"/>
                    <GridViewColumn Header = "id" DisplayMemberBinding="{Binding Path=id}" Width="100"/>
                    <GridViewColumn Header = "Name" DisplayMemberBinding="{Binding Path=Name}" Width="100"/>
                    <GridViewColumn Header = "Quantity" DisplayMemberBinding="{Binding Path=Quantity}" Width="100"/>
                    <GridViewColumn Header = "NetPrice" DisplayMemberBinding="{Binding Path=NetPrice}" Width="100"/>
                    <GridViewColumn Header = "GrossPrice" DisplayMemberBinding="{Binding Path=GrossPrice}" Width="100"/>
                    <GridViewColumn Header = "TotalCost" DisplayMemberBinding="{Binding Path=TotalCost}" Width="100"/>
                </GridView>
            </ListView.View>
        </ListView>
    </BlockUIContainer>
</FlowDocument>

对我来说看起来不错。不知道问题出在哪里

【问题讨论】：

标签： c# wpf xaml mvvm mvvm-light

【解决方案1】：

这不是 ObservableCollection 的问题，而是设置 Products 属性。

Products = new ObservableCollection<ProductModel>();

您在 GetData 方法中设置它，但您从未通知视图有关它，因此它没有绑定到您的 ObservableCollection。您可以改为在构造函数中设置属性，或者在属性上也使用 INotifyPropertyChanged。

【讨论】：

咳咳，我现在明白了。我整天坐着做这个项目。我需要新鲜空气

【解决方案2】：

我看到您已经从 ViewModelBase 继承，因此您不需要这样做：

public event PropertyChangedEventHandler PropertyChanged;

    // This method is called by the Set accessor of each property.
    // The CallerMemberName attribute that is applied to the optional propertyName
    // parameter causes the property name of the caller to be substituted as an argument.
    private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

相反，您可以这样做：

public class MainViewModel : ViewModelBase{
public ObservableCollection<ProductModel> Products { get; set; }

private void GetData()
{
    //getting data here

    Products = new ObservableCollection<ProductModel>();

    foreach (var item in myData)
    {
        Products.Add(item);
    }
    RaisePropertyChanged(nameof(Products)); // you are missing this
}}

【讨论】：