那些遇到过的问题

WPF MVVM 如何使用 ShowDialog() 上的绑定预填充文本框？

Pho*_*que 1 c# wpf dialog mvvm

我有一个用 a 显示的表单窗口ShowDialog()，文本框绑定到视图模型中的属性。我像这样打开我的对话框（简化版）：

FilterWindowView wnd = new FilterWindowView();
FilterWindowViewModel fvm = new FilterWindowViewModel(licenseRecords) { wnd = wnd };
wnd.DataContext = fvm;
fvm.RestoreCurrentFilters();
if (wnd.ShowDialog() ?? false)
{
    //...
}
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我在表单中设置的属性用作过滤器参数，我将其存储在静态类中以检索以备后用。

我想要做的是让文本框自动填充存储在这个静态类中的当前值。

我的文本框绑定属性如下所示：

    private string _product;
    public string product
    {
        get { return _product; }
        set
        {
            if (_product == value)
                return;
            _product = value;
            Helper.product = value;
            if (value != "")
                chkProduct = true;
            OnPropertyChanged();
        }
    }
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（我认为在验证时重新分配可能会更好的性能，但这是另一个问题......）我的问题是，如果我设置一个值（即在构造函数中），该值会被设置，但是在调用时ShowDialog()，该值是重置为“”。

还尝试在实例化 VM 后调用方法，但如上所述，显示窗口时（调用时ShowDialog()）会发生此重置...

此表单生成一个我在 VM 中恢复的自定义对象，dialogResult因此wnd.Show()我无法选择然后设置为存储值（我猜？）。

谢谢你的帮助。

EDIT View 非常简单，只有几个标签和文本框以两种方式绑定到 VM。

<Window x:Class="LicenseManager.View.FilterWindowView"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:LicenseManager.View"
    mc:Ignorable="d"
    Title="FilterWindowView" Height="306.412" Width="284.216">
<Grid>
    <CheckBox Content="Product" HorizontalAlignment="Left" Margin="10,10,0,0" VerticalAlignment="Top" IsChecked="{Binding chkProduct}"/>
    <TextBox HorizontalAlignment="Left" Height="23" Margin="137,8,0,0" TextWrapping="Wrap" Text="{Binding product, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Top" Width="120"/>
    <CheckBox Content="Client" HorizontalAlignment="Left" Margin="10,38,0,0" VerticalAlignment="Top" IsChecked="{Binding chkClient}"/>
    <TextBox HorizontalAlignment="Left" Height="23" Margin="137,36,0,0" TextWrapping="Wrap" Text="{Binding client, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Top" Width="120"/>
    <CheckBox Content="Date After" HorizontalAlignment="Left" Margin="10,66,0,0" VerticalAlignment="Top" IsChecked="{Binding chkDateAfter}"/>
    <TextBox HorizontalAlignment="Left" Height="23" Margin="137,64,0,0" TextWrapping="Wrap" Text="{Binding dateAfter, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Top" Width="120"/>
    <CheckBox Content="Date Before" HorizontalAlignment="Left" Margin="10,94,0,0" VerticalAlignment="Top" IsChecked="{Binding chkDateBefore}"/>
    <TextBox HorizontalAlignment="Left" Height="23" Margin="137,92,0,0" TextWrapping="Wrap" Text="{Binding dateBefore, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Top" Width="120"/>
    <CheckBox Content="Sbs__no" HorizontalAlignment="Left" Margin="10,122,0,0" VerticalAlignment="Top" IsChecked="{Binding chkSbsNo}"/>
    <TextBox HorizontalAlignment="Left" Height="23" Margin="137,120,0,0" TextWrapping="Wrap" Text="{Binding sbsNo, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Top" Width="120"/>
    <CheckBox Content="Store__no" HorizontalAlignment="Left" Margin="10,150,0,0" VerticalAlignment="Top" IsChecked="{Binding chkStoreNo}"/>
    <TextBox HorizontalAlignment="Left" Height="23" Margin="137,148,0,0" TextWrapping="Wrap" Text="{Binding storeNo, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Top" Width="120"/>
    <CheckBox Content="Workstation__no" HorizontalAlignment="Left" Margin="10,178,0,0" VerticalAlignment="Top" IsChecked="{Binding chkWorkstationNo}"/>
    <TextBox HorizontalAlignment="Left" Height="23" Margin="137,176,0,0" TextWrapping="Wrap" Text="{Binding workstationNo, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Top" Width="120"/>
    <CheckBox Content="Comment" HorizontalAlignment="Left" Margin="10,206,0,0" VerticalAlignment="Top" IsChecked="{Binding chkWorkstationNo}"/>
    <TextBox HorizontalAlignment="Left" Height="23" Margin="137,204,0,0" TextWrapping="Wrap" Text="{Binding comment, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Top" Width="120"/>
    <Button Content="Apply" Command="{Binding apply}" HorizontalAlignment="Left" Margin="10,236,0,0" VerticalAlignment="Top" Width="75"/>
</Grid>
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编辑视图模型类助手是我的静态类

    class FilterWindowViewModel : INotifyPropertyChanged
        {
            #region Attributes
            public Window wnd; // For dialog closer
            public List<LicenseRecordModel> list;
            public List<LicenseRecordModel> dialogResult;
            public event PropertyChangedEventHandler PropertyChanged;

            string tmpProduct;
            string tmpClient;
            string tmpDateAfter;
            string tmpDateBefore;
            string tmpSbsNo;
            string tmpStoreNo;
            string tmpWorkstationNo;
            string tmpComment;
            #endregion

            #region Properties
            //Properties and commands
        private string _comment;
        public string comment
        {
            get { return _comment; }
            set
            {
                if (_comment == value)
                    return;
                _comment = value;
                Helper.comment = value;
                if (value != "")
                    chkComment = true;
                OnPropertyChanged();
            }
        }


//...
        private DelegateCommand _apply;
        public DelegateCommand apply
        {
            get
            {
                return _apply ?? (_apply = new DelegateCommand(o => Apply(), o => true));
            }
        }
            #endregion

            #region Init
            public FilterWindowViewModel(IEnumerable<LicenseRecordModel> source)
            {
                tmpProduct = Helper.product;
                tmpClient = Helper.client;
                tmpDateAfter = Helper.dateAfter;
                tmpDateBefore= Helper.dateBefore;
                tmpSbsNo = Helper.sbsNo;
                tmpStoreNo = Helper.storeNo;
                tmpWorkstationNo = Helper.workstationNo;
                tmpComment = Helper.comment;
                list = new List<LicenseRecordModel>(source);
            }

            public void RestoreCurrentFilters()
            {
                product = tmpProduct;
                client = tmpClient;
                dateAfter = tmpDateAfter;
                dateBefore = tmpDateBefore;
                sbsNo = tmpSbsNo;
                storeNo = tmpStoreNo;
                workstationNo = tmpWorkstationNo;
                comment = tmpComment;
            }

            protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
            {
                PropertyChangedEventHandler handler = PropertyChanged;

                if (handler != null)
                {
                    handler(this, new PropertyChangedEventArgs(propertyName));
                }
            }
            #endregion

            private bool Accept(LicenseRecordModel lic)
            {
                var tmp = list;
                tmp = list.Where(x => 
                chkProduct ? x.Product.Contains(product) : true &&
                chkClient ? x.Client.Contains(client) : true &&
                chkProduct ? x.Product.Contains(product) : true &&
                chkProduct ? x.Product.Contains(product) : true &&
                chkProduct ? x.Product.Contains(product) : true &&
                chkProduct ? x.Product.Contains(product) : true &&
                chkProduct ? x.Product.Contains(product) : true
                ).ToList();
                return false;
            }

            #region Commands
            public void Apply()
            {
                var tmp = new List<LicenseRecordModel>(list);
                dialogResult = new List<LicenseRecordModel>(list);
                string message = "";
                if (chkProduct)
                {
                    dialogResult =tmp.Where(x => x.Product.Contains(product.ToUpper())).ToList();
                    tmp = dialogResult;
                }
                if (chkClient)
                {
                    dialogResult = tmp.Where(x => x.Client.Contains(client.ToUpper())).ToList();
                    tmp = dialogResult;
                }
                if (chkDateAfter)
                {
                    DateTime after;
                    if (chkDateBefore)
                    {
                        DateTime before;
                        if (DateTime.TryParse(dateAfter, out after))
                        {
                            if (DateTime.TryParse(dateBefore, out before))
                            {
                                dialogResult = tmp.Where(x => DateTime.ParseExact(x.CreationDate, "yyyy-MM-dd", null) <= after && DateTime.ParseExact(x.CreationDate, "yyyy-MM-dd", null) >= before).ToList(); ;
                                tmp = dialogResult;
                            }
                            else message += "'Date Before' is not a valid date (yyyy-mm-dd)";
                        }
                        else message += "'Date After' is not a valid date (yyyy-mm-dd)";
                    }
                    else if (DateTime.TryParse(dateAfter, out after))
                    {
                        dialogResult = tmp.Where(x => DateTime.ParseExact(x.CreationDate, "yyyy-MM-dd", null) >= after).ToList();
                        tmp = dialogResult;
                    }
                    else message += "'Date After' is not a valid date (yyyy-mm-dd)";
                }
                if (chkDateBefore)
                {
                    DateTime before;
                    if (DateTime.TryParse(dateBefore, out before))
                    {
                        dialogResult = tmp.Where(x => DateTime.ParseExact(x.CreationDate, "yyyy-MM-dd", null) <= before).ToList();
                        tmp = dialogResult;
                    }
                    else message += "'Date After' is not a valid date (yyyy-mm-dd)";
                }
                if (chkSbsNo)
                {
                    dialogResult = tmp.Where(x => x.SbsNo.Contains(sbsNo)).ToList();
                    tmp = dialogResult;
                }
                if (chkStoreNo)
                {
                    dialogResult = tmp.Where(x => x.StoreNo.Contains(storeNo)).ToList();
                    tmp = dialogResult;
                }
                if (chkWorkstationNo)
                {
                    dialogResult = tmp.Where(x => x.WorkstationNo.Contains(workstationNo)).ToList();
                    tmp = dialogResult;
                }
                if (chkComment)
                {
                    dialogResult = tmp.Where(x => x.Comment.ToUpper().Contains(comment.ToUpper())).ToList();
                    tmp = dialogResult;
                }
                if (message != "")
                {
                    MessageBox.Show(message);
                }
                else
                {
                    DialogCloser.SetDialogResult(wnd, true);
                }
            }
            #endregion
        }
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编辑：更新了绑定设置为 TwoWay 的视图（已解决）

Bio*_*ode 5

几个问题：

1) 由于您要将Helper（视图模型默认）值发送TextBox.Text到绑定，因此必须至少为OneWay（源 --> 目标）。因为您还希望将输入数据从 发送TextBox.Text到视图模型，所以绑定变为TwoWay（源 <--> 目标）。

由于TwoWay是属性的默认值Binding.Mode，TextBox.Text您可以安全地Binding.Mode从绑定表达式中删除：

<TextBox Text="{Binding product, UpdateSourceTrigger=PropertyChanged}" />
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2）您不需要Helper该类来存储数据。只需向实例化对话框的类添加一个属性即可。
此外，您不再需要 视图模型中的RestoreCurrentFilters()方法和一堆tmp...字段。

public partial class MainWindow
{
  // Shared and reused view model instance
  private FilterWindowViewModel DialogViewModel{ get; set; }

  public MainWindow()
  { 
    this.DialogViewModel = new FilterWindowViewModel();
  }

  private void ShowDialog()
  {
    var dialog = new FilterWindowView() { DataContext = this.DialogViewModel };
    if (dialog.ShowDialog() ?? false)
    {
      //...
    }
  }
}
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FilterWindowViewModel.cs

public class FilterWindowViewModel 
{
  private string _product;
  public string Product
  {
    get => _product; 
    set
    {
      if (_product == value)
        return;

      _product = value;

      this.chkProduct = !string.IsNullOrWhiteSpace(value);
      OnPropertyChanged();
    }
  }
}
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3) 您的视图模型不应引用Window.
4) 首选数据验证。只需执行INotifyDataErrorInfo. 例子

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