c# - 你如何将 ObservableCollection 放入 Textblock

Question

我需要将 myObservableCollection<ValidationMessage>放入我的TextBlock. 这是我的代码。现在它正在显示项目和子项目，但在消息显示它的位置System.Collections.ObjectModel.ObservableCollection'1[ValidationWPF.DataSources.‌ValidationMessages]。

我认为这是因为它不能ObservableCollection放入TextBlock.

XAML：

<UserControl x:Class="ValidationWPF.ValidationUserControl"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
             xmlns:local="clr-namespace:ValidationWPF.DataSources"
             mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="300">
    <UserControl.Resources>
        <DataTemplate x:Key="Messages">
            <TextBlock Text="{Binding Message}"/>
        </DataTemplate>



    </UserControl.Resources>
    <Grid x:Name="LayoutRoot" Background="White">

        <telerik:RadTreeView x:Name="radTreeView" Margin="8">
            <telerik:RadTreeView.ItemTemplate>



                <HierarchicalDataTemplate ItemsSource="{Binding SubItems}">
                    <TextBlock Text="{Binding item}" />
                </HierarchicalDataTemplate>

            </telerik:RadTreeView.ItemTemplate>
        </telerik:RadTreeView>

    </Grid>
</UserControl>

验证消息类：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ValidationWPF.DataSources
{
    public class ValidationMessage
    {
        public ValidationMessage(string Message)
        {
            this.Message = Message;
        }

        public string Message
        {
            get;
            set;
        }

    }
}

验证项类：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections.ObjectModel;

namespace ValidationWPF.DataSources
{
   public class ValidationItem : ObservableCollection<ValidationItem>
    {
        public ValidationItem()
        {
            SubItems = new ObservableCollection<ValidationItem>();


        }


        public ObservableCollection<ValidationMessage> Message
        {
            get;
            set;
        }

        public string item
        {
            get;
            set;
        }

        public IList<ValidationItem> SubItems
        {
            get;
            set;
        }

        public static IList<ValidationItem> GetItems(string name)
        {
            var Validation = new ObservableCollection<ValidationItem>();


            var item = new ValidationItem();
            item.item = "Customer";


            var subItem = new ValidationItem();
            subItem.item = "Name";
            item.SubItems.Add(subItem);

            var Message = new ValidationItem();
            Message.item = new ObservableCollection<ValidationMessage>().ToString();
            subItem.SubItems.Add(Message);






            Validation.Add(item);

            return Validation;

        }
    }
}

谢谢您的帮助！！

score 3 · Accepted Answer

问题是的Text属性TextBlock是一个字符串，而你给它一个ObservableCollection. WPF 知道转换两者的唯一方法是调用ObservableCollection.ToString()，它返回类的完整类型名称。

解决方法是ObservableCollection通过创建一个实现System.Windows.Data.IValueConverter的类将您的转换为字符串。这使您可以控制转换。

你可以像这样实现它：

using System.Globalization;
using System.Text;
using System.Windows.Data;

namespace ValidationWPF.DataSources
{
    class CollectionConverter : IValueConverter
    {
        object Convert(object value, Type targetType,object parameter,CultureInfo culture)
        {
            ObservableCollection<ValidationMessage> messages = (ObservableCollection<ValidationMessage>)value;

            var sb = new StringBuilder();
            foreach(var msg in messages)
            {
                sb.AppendLine(msg.Message);
            }

            return sb.ToString();
        }

        object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return null;
        }
    }
}

您可以在 XAML 文件中像这样使用它：

<UserControl x:Class="ValidationWPF.ValidationUserControl"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
             xmlns:local="clr-namespace:ValidationWPF.DataSources"
             mc:Ignorable="d"
             d:DesignHeight="300" d:DesignWidth="300">
    <UserControl.Resources>
        <local:CollectionConverter x:Key="CollectionConverter" />

        <DataTemplate x:Key="Messages">
            <TextBlock Text="{Binding Message, Converter={StaticResource CollectionConverter}}"/>
        </DataTemplate>
    </UserControl.Resources>
    ...
</UserControl>

现在 WPF 将CollectionConverter.Convert()在需要填充您的TextBlock.

score 2 · Accepted Answer

我最终以一种不同且更清洁的方式进行操作。

XAML：

<UserControl x:Class="ValidationWPF.ValidationUserControl"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
             xmlns:local="clr-namespace:ValidationWPF.DataSources"
             mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="300">
    <UserControl.Resources>
        <!--<local:CollectionConverter x:Key="CollectionConverter"/>
            <DataTemplate x:Key="Messages">
            <TextBlock Text="{Binding Message}"/>
        </DataTemplate>--> 




    </UserControl.Resources>
    <Grid x:Name="LayoutRoot" Background="White">

        <telerik:RadTreeView x:Name="radTreeView" Margin="8" ItemsSource="{Binding Errors}">
            <telerik:RadTreeView.ItemTemplate>
                 <HierarchicalDataTemplate ItemsSource="{Binding SubItems}" >
                    <Grid>
                        <Grid.RowDefinitions>
                            <RowDefinition/>
                            <RowDefinition/>
                        </Grid.RowDefinitions>
                        <TextBlock Text="{Binding Description}"/>

                        <ListBox Grid.Row="1" ItemsSource="{Binding Messages}">
                            <ListBox.ItemTemplate>
                                <DataTemplate>
                                    <TextBlock Text="{Binding Message}"/>
                                </DataTemplate>
                            </ListBox.ItemTemplate>
                        </ListBox>
                    </Grid>

                </HierarchicalDataTemplate>

            </telerik:RadTreeView.ItemTemplate>
        </telerik:RadTreeView>

    </Grid>
</UserControl>

验证消息类：

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;

    namespace ValidationWPF.DataSources
    {
        public class ValidationMessage
        {
            public ValidationMessage(string name, string Message)
            {
                this.Message = Message;
                this.PropertyName = name;
            }

            public string Message
            {
                get;
                set;
            }

            public string PropertyName { get; set; }

        }
    }

VALIDATIONVIEWMODEL CLASS:

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Collections.ObjectModel;

    namespace ValidationWPF.DataSources
    {
        public class ValidationViewModel
        {
            public ValidationViewModel()
            {
                this.Errors = new ObservableCollection<ValidationItem>();

                ValidationItem item = new ValidationItem();
                item.Description = "Customer";

                ValidationMessage msg = new ValidationMessage("FirstName", "First name is required");
                item.Messages.Add(msg);


                this.Errors.Add(item);

                ValidationItem item2 = new ValidationItem();
                item2.Description = "Order";

                msg = new ValidationMessage("Quantity", "Quantity must be greater than zero");
                item2.Messages.Add(msg);


                item.SubItems.Add(item2);

            }

            public ObservableCollection<ValidationItem> Errors { get; set; }
        }
    }

验证用户控制类：

  public partial class ValidationUserControl : UserControl
    {
        public ValidationUserControl()
        {
            InitializeComponent();
            this.DataContext = new ValidationViewModel();

        }

    }

score 2 · Accepted Answer

你说的对。TextBlock 尝试将属性值视为字符串，而 ObservableCollection.ToString 将返回您所看到的内容。

您可以做的是添加一个新属性，将 ObservableCollection 的所有消息组合成一个字符串。像这样的东西：

public string MessagesCombined  
{
   get { return string.Join(Environment.NewLine, Message.Select(m => m.Message)); } 
}

这会将 ObservableCollection 中的所有消息组合成一个字符串，每个项目由换行符分隔。（您可能需要对我的代码进行一些修改，我正在编写此代码而无需访问编译器......）。

c# - 你如何将 ObservableCollection 放入 Textblock

3 回答 3

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