c# - 无法以编程方式设置 WPF 的 ComboBox 项文本

Question

我已经阅读了很多关于这个主题的资料，但我越来越感到沮丧和困惑，因为在没有 MVVM 的情况下，像这样简单的事情很难做到。

我将列表设置为:

cboLender.ItemsSource = lenders;

源列表是包含 Lender 对象的自定义类型列表。其属性如下:ID 和 CompanyName。

然后以编程方式将其设置为:

        var selectedLender = lenders.SingleOrDefault(x => x.ID == _someId);
        cboLender.SelectedItem = selectedLender;
        cboLender.SelectedValuePath = "CompanyName";
        cboLender.SelectedValue = selectedLender.CompanyName;
        //cboLender.DisplayMemberPath = "CompanyName";

在代码中，项目被正确设置成为SelectedItem，但在用户界面上，组合框是空的。所以它看起来像没有被选中。我也尝试了显示成员路径属性，但这也不起作用。

这是一个如此简单的问题，但我现在一直在尝试和研究我们的问题，现在我需要帮助。

Answer 1

试试这段代码

 LenderList = new ObservableCollection<Lender>();
            Lender l = new Lender();
            l.CompanyName = "11212dffdd";
            l.ID = "1";
            LenderList.Add(l);
            cboLender.ItemsSource = LenderList;
            cboLender.DisplayMemberPath = "CompanyName";


            var selectedLender = LenderList.SingleOrDefault(x => x.ID == "1");
            cboLender.SelectedItem = selectedLender;
            cboLender.SelectedValuePath = "CompanyName";
            cboLender.SelectedValue = selectedLender.CompanyName;

代码隐藏

namespace WpfApplication1
{

    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        #region Inotify
        /// <summary>
        /// Property Change Event
        /// </summary>
        public event PropertyChangedEventHandler PropertyChanged;

        /// <summary>
        /// Property Change Method
        /// </summary>
        /// <param name="prop">Property Name</param>
        internal void RaisePropertyChanged(string prop)
        {
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged(this, new PropertyChangedEventArgs(prop));
            }
        }

        #endregion

        #region Constructor

        public MainWindow()
        {
            this.DataContext = this;
            InitializeComponent();
        }
        #endregion

        #region Properties

        private ObservableCollection<Lender> lenderList;

        public ObservableCollection<Lender> LenderList
        {
            get { return lenderList; }
            set
            {
                lenderList = value;
                RaisePropertyChanged("LenderList");
            }
        }
        #endregion

        #region Events


        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            LenderList = new ObservableCollection<Lender>();
            Lender l = new Lender();
            l.CompanyName = "11212dffdd";
            l.ID = "1";
            LenderList.Add(l);
            cboLender.ItemsSource = LenderList;
            cboLender.DisplayMemberPath = "CompanyName";


            var selectedLender = LenderList.SingleOrDefault(x => x.ID == "1");
            cboLender.SelectedItem = selectedLender;
            cboLender.SelectedValuePath = "CompanyName";
            cboLender.SelectedValue = selectedLender.CompanyName;

        }
        #endregion
    }

    public class Lender : INotifyPropertyChanged
    {
        #region Inotify
        /// <summary>
        /// Property Change Event
        /// </summary>
        public event PropertyChangedEventHandler PropertyChanged;

        /// <summary>
        /// Property Change Method
        /// </summary>
        /// <param name="prop">Property Name</param>
        internal void RaisePropertyChanged(string prop)
        {
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged(this, new PropertyChangedEventArgs(prop));
            }
        }

        #endregion

        private string companyName;

        public string CompanyName
        {
            get { return companyName; }
            set
            {
                companyName = value;
                RaisePropertyChanged("CompanyName");
            }
        }

        private string id;

        public string ID
        {
            get { return id; }
            set
            {
                id = value;
                this.RaisePropertyChanged("ID");
            }
        }
    }
}

在 xaml 中

<Window x:Class="WpfApplication1.MainWindow"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:cef="clr-namespace:WpfApplication1"
        xmlns:sys="clr-namespace:System;assembly=mscorlib"
    Title="Window1" x:Name="testWindow" Height="500" Loaded="Window_Loaded" Width="300" >
    <Grid >
        <StackPanel x:Name="stk">
            <ComboBox x:Name="cboLender" Width="100"/>
        </StackPanel>
    </Grid>
</Window>