Question

我有一个文本框，我希望绑定到组合框selecteItem的默认值，同时我希望我的文本框绑定到Mvvm对象属性？我在这里查了一下，但多重绑定让我很困惑。我更愿意为此问题提供xaml解决方案。

增加：

在组合框中我将选择一个帐户，该帐户包含一些值（金额），我想显示金额，但需要我的文本框被绑定到mvvm模型对象元素stAmount。因此，用户可以更改由combobbox选择的数量，然后可以将此修改或未更改的金额值存储到文本框绑定的模型 - 对象元素（stAmount）

Answer 1

在我看来，您希望将文本框绑定到viewmodel中的选定值属性而不是组合框。

using System.Collections.ObjectModel;
using System.Windows;

namespace WpfApplication1
{
    public partial class MainWindow : Window
    {
        public ObservableCollection<string> Items
        {
            get { return (ObservableCollection<string>)GetValue(ItemsProperty); }
            set { SetValue(ItemsProperty, value); }
        }

        public static readonly DependencyProperty ItemsProperty =
            DependencyProperty.Register("Items", typeof(ObservableCollection<string>), typeof(MainWindow), new PropertyMetadata(null));


        public string SelectedValue
        {
            get { return (string)GetValue(SelectedValueProperty); }
            set { SetValue(SelectedValueProperty, value); }
        }

        public static readonly DependencyProperty SelectedValueProperty =
            DependencyProperty.Register("SelectedValue", typeof(string), typeof(MainWindow), new PropertyMetadata(null));


        public MainWindow()
        {
            InitializeComponent();
            Items = new ObservableCollection<string>();
            Items.Add("Value 1");
            Items.Add("Value 2");
            Items.Add("Value 3");
            Items.Add("Value 4");
            Items.Add("Value 5");
            Items.Add("Value 6");
        }
    }
}

和xaml

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        DataContext="{Binding RelativeSource={RelativeSource Self}}"
        Title="MainWindow" Height="350" Width="525">
    <Grid >
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition/>
        </Grid.RowDefinitions>

        <ComboBox Grid.Row="0" ItemsSource="{Binding Items}" SelectedItem="{Binding SelectedValue}"/>
        <TextBox Grid.Row="1" Text="{Binding SelectedValue}"/>
    </Grid>
</Window>

Answer 2

利用INotifyPropertyChanged：

XAML

<Window x:Class="INotifyPropertyChangedExample.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        DataContext="{Binding RelativeSource={RelativeSource Self}}"
        Title="INotifyPropertyChanged Example" Width="380" Height="100">
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="150" />
            <ColumnDefinition />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>
        <Label Content="Account Name:" />
        <Label Grid.Row="1" Grid.Column="0" Content="Account Balance:" />
        <ComboBox Grid.Row="0" Grid.Column="1" Width="200" Height="25" ItemsSource="{Binding AccountsCollection}" SelectedItem="{Binding SelectedAccount}" DisplayMemberPath="Name" />
        <TextBox Grid.Column="1" Grid.Row="1" Width="200" Height="25" Text="{Binding SelectedAccount.Balance}" />
    </Grid>
</Window>

C＃

namespace INotifyPropertyChangedExample
{
    using System.Collections.ObjectModel;
    using System.ComponentModel;
    using System.Windows;

    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        private ObservableCollection<Account> acctountsCollection;
        public ObservableCollection<Account> AccountsCollection
        {
            get
            {
                return this.acctountsCollection;
            }
            set
            {
                this.acctountsCollection = value;
                OnPropertyChanged();
            }
        }

        private Account selectedAccount;
        public Account SelectedAccount
        {
            get
            {
                return this.selectedAccount;
            }
            set
            {
                this.selectedAccount = value;
                OnPropertyChanged();
            }
        }

        public MainWindow()
        {
            InitializeComponent();
            this.AccountsCollection = new ObservableCollection<Account>()
            {
                new Account { Id = 1, Name = "My super account", Balance = 123.45 },
                new Account { Id = 2, Name = "My super account 2", Balance = 543.21 },
            };
        }

        public event PropertyChangedEventHandler PropertyChanged;
        protected virtual void OnPropertyChanged(string propertyName = null)
        {
            var handler = PropertyChanged;
            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }

    public class Account
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public double Balance { get; set; }
    }
}

在此示例中，我们将ObservableCollection个Account个对象绑定到您的ComboBox，并跟踪通过Account属性选择的SelectedItem。我们将TextBox text属性绑定到所选Balance对象的Account属性。因此，当选定的Account对象更改后，TextBox中显示的值会发生变化，以反映Balance的{{1}}。

此外，如果您更改Account中的值，则TextBox对象的Balance值会更新。

将文本框绑定到两个源WPF

2 个答案: