Question

我有一个列表视图，该列表为我提供了参加活动的所有人员的列表。在组合框中选择了该事件，并且listview应该从数据库的List <>中吸引参与者。我想每次选择更改时都执行此操作。我必须警告你，我对此很陌生。但是我已经从互联网上尝试了很多示例和代码，但是它们只是行不通..我使用以下代码：

C＃

    private void cbEvenement_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        // this is he eventID extracted from the list by using the Selected index
        evid = _evenementen[cbEvenement.SelectedIndex].EvenementID;
        //I give the EventID to the Method in my database connector 
        //to get the right participants from the right event.
        aanmeldingen = Connect.EvenementAanmeldingen(evid);

        // getting everything ready for the listview, i have a constructor class
        foreach (var aanmelding in aanmeldingen)
        {
            aanmeldingclass.Add(new AanmeldingEvenement()
            {
                Voornaam = aanmelding.voornaam,
                Achternaam = aanmelding.achternaam
            });


        }
        // setting the itemsource
        LVAanmeldingen.ItemsSource = aanmeldingclass;
        // saw this on the internet. But it is not working?
        CollectionViewSource.GetDefaultView(aanmeldingclass).Refresh();

    }

Xaml

                <ListView x:Name="LVAanmeldingen" HorizontalAlignment="Left" Height="458" Margin="3,67,0,0" VerticalAlignment="Top" Width="268" ItemsSource="{Binding AanmeldingCollection}">
                    <ListView.View>
                        <GridView>
                            <GridViewColumn Header="Voornaam" Width="auto" DisplayMemberBinding="{Binding Voornaam}" ></GridViewColumn>
                            <GridViewColumn Header="Achternaam" Width="auto" DisplayMemberBinding="{Binding Achternaam}" ></GridViewColumn>
                        </GridView>
                    </ListView.View>
                </ListView>

班级

       class AanmeldingEvenement
       {
         public string Voornaam { get; set; }
         public string Achternaam { get; set; }
       }

在互联网上找到：

    private ObservableCollection<AanmeldingEvenement> Aanmeldingcollection;

    public ObservableCollection<AanmeldingEvenement> AanmeldingCollection
    {
        get
        {
            if (Aanmeldingcollection == null)
            {
                Aanmeldingcollection = new ObservableCollection<AanmeldingEvenement>();
            }
            return Aanmeldingcollection;
        }
        set
        {
            Aanmeldingcollection = value;
        }
    }

我真的被困在这里，我想要的只是Listview，向我展示参与者并找到与数据库中的事件相关的合适参与者

Answer 1

据我所知，您正在像使用WinfForms一样进行编码。对于WPF，我强烈建议您使用MVVM模式和DataBinding。否则，您会丢失太多东西，无法使WPF值得。

这是我的答案（请问是否需要）：

我建立了两个班来管理事件和人民。我决定将People注册到其他Events，但这可能是相反的，也可能是其他解决方案：

public class People
{
     public string firstName { get; set; }
     public string lastName { get; set; }

     public List<Event> registeredEvents { get; set; }

     public People()
     {
         registeredEvents = new List<Event>();
     }
}

public class Event
{
     public string name { get; set; }
     public string anyInfo { get; set; }
}

然后我有一个EventManager，它将收集信息并执行逻辑。当然，您必须根据数据库和程序的其他部分对其进行修改：

public class EventManager : INotifyPropertyChanged
{
    public List<Event> events { get; set; }
    public List<People> peoples { get; set; }

    //this is the current event that correspond to the selected event in your combobox
    private Event _currentEvent;
    public Event currentEvent
    {
        get
        {
            return _currentEvent;
        }
        set
        {
            if (_currentEvent != value)
            {
                _currentEvent = value;
                //when you change the selected event, you have to update the list of participants
                OnPropertyChanged("participants");
            }
        }
    }

    public List<People> participants
    {
        get
        {
            //Here is the code to retrieve the people that registered to the selected event
            return peoples.Where(p => p.registeredEvents.Contains(currentEvent)).ToList<People>();
        }
    }

    public EventManager()
    {
        events = new List<Event>();
        peoples = new List<People>();
    }

    //The following lines are specific to WPF and DataBinding
    public event PropertyChangedEventHandler PropertyChanged;

    protected void OnPropertyChanged(string name)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(name));
        }
    }
}

Here you can find more information about Databinding

然后是XAML。它仅依赖于DataContext：

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition />
        <ColumnDefinition />
    </Grid.ColumnDefinitions>
    <ComboBox ItemsSource="{Binding events}" SelectedItem="{Binding currentEvent}">
        <ComboBox.ItemTemplate>
            <DataTemplate>
                <TextBlock Text="{Binding name}"/>
            </DataTemplate>
        </ComboBox.ItemTemplate>
    </ComboBox>
    <ListView Grid.Column="1" ItemsSource="{Binding participants}">
        <ListView.View>
            <GridView>
                <GridViewColumn Header="First Name" DisplayMemberBinding="{Binding firstName}"/>
                <GridViewColumn Header="Last Name" DisplayMemberBinding="{Binding lastName}"/>
            </GridView>
        </ListView.View>
    </ListView>
</Grid>

最后，这是我添加Data的代码。当然，您的角色应该有所不同。重要的是Datacontext和我真的不在乎ComboBox或ListView的事实。

public MainWindow()
{
    InitializeComponent();
    EventManager eventManager = new EventManager();

    Event wedding = new Event() { name = "Wedding" };
    Event meeting = new Event() { name = "Meeting with LunaStar" };
    Event skiSession = new Event() { name = "Skiing in Oklahoma" };

    People bob = new People() { firstName = "Bob", lastName = "Raz." };
    People irina = new People() { firstName = "Irina", lastName = "Politov." };
    People kumamoto = new People() { firstName = "Kumamoto", lastName = "San" };

    bob.registeredEvents.Add(wedding);
    bob.registeredEvents.Add(meeting);
    bob.registeredEvents.Add(skiSession);

    irina.registeredEvents.Add(wedding);
    irina.registeredEvents.Add(meeting);

    kumamoto.registeredEvents.Add(meeting);
    kumamoto.registeredEvents.Add(skiSession);

    eventManager.peoples = new List<People>() { bob, irina, kumamoto };
    eventManager.events = new List<Event>() { wedding, meeting, skiSession };

    DataContext = eventManager;
}

如何刷新Listview Itemsource？ WPF Xaml

1 个答案: