在WPF可以过滤不落后code一CollectionViewSource？ [英] In WPF can you filter a CollectionViewSource without code behind?

问题描述

真正的主题说明了一切。

Really the subject says it all.

<CollectionViewSource x:Key="MyData"
    Source="{Binding}" Filter="{ SomethingMagicInXaml? }" />

这不，我不能有code后面。它只是唠叨我。

It's not that I can't have code behind. It just nags at me.

推荐答案

您可以做在XAML pretty多的东西，如果你努力不够，的up~~V在它编写程序整体。

You can do pretty much anything in XAML if you "try hard enough", up to writing whole programs in it.

您将永远围绕落后code得到（当然，如果你使用的库不必编写任何但是应用仍然依赖于它当然），这里是你可以在这个特定的做一个例子案例：

You will never get around code behind (well, if you use libraries you don't have to write any but the application still relies on it of course), here's an example of what you can do in this specific case:

<CollectionViewSource x:Key="Filtered" Source="{Binding DpData}"
                      xmlns:me="clr-namespace:Test.MarkupExtensions">
    <CollectionViewSource.Filter>
        <me:Filter>
            <me:PropertyFilter PropertyName="Name" Value="Skeet" />
        </me:Filter>
    </CollectionViewSource.Filter>
</CollectionViewSource>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Markup;
using System.Windows.Data;
using System.Collections.ObjectModel;
using System.Windows;
using System.Text.RegularExpressions;

namespace Test.MarkupExtensions
{
    [ContentProperty("Filters")]
    class FilterExtension : MarkupExtension
    {
        private readonly Collection<IFilter> _filters = new Collection<IFilter>();
        public ICollection<IFilter> Filters { get { return _filters; } }

        public override object ProvideValue(IServiceProvider serviceProvider)
        {
            return new FilterEventHandler((s, e) =>
                {
                    foreach (var filter in Filters)
                    {
                        var res = filter.Filter(e.Item);
                        if (!res)
                        {
                            e.Accepted = false;
                            return;
                        }
                    }
                    e.Accepted = true;
                });
        }
    }

    public interface IFilter
    {
        bool Filter(object item);
    }

    // Sketchy Example Filter
    public class PropertyFilter : DependencyObject, IFilter
    {
        public static readonly DependencyProperty PropertyNameProperty =
            DependencyProperty.Register("PropertyName", typeof(string), typeof(PropertyFilter), new UIPropertyMetadata(null));
        public string PropertyName
        {
            get { return (string)GetValue(PropertyNameProperty); }
            set { SetValue(PropertyNameProperty, value); }
        }
        public static readonly DependencyProperty ValueProperty =
            DependencyProperty.Register("Value", typeof(object), typeof(PropertyFilter), new UIPropertyMetadata(null));
        public object Value
        {
            get { return (object)GetValue(ValueProperty); }
            set { SetValue(ValueProperty, value); }
        }
        public static readonly DependencyProperty RegexPatternProperty =
            DependencyProperty.Register("RegexPattern", typeof(string), typeof(PropertyFilter), new UIPropertyMetadata(null));
        public string RegexPattern
        {
            get { return (string)GetValue(RegexPatternProperty); }
            set { SetValue(RegexPatternProperty, value); }
        }

        public bool Filter(object item)
        {
            var type = item.GetType();
            var itemValue = type.GetProperty(PropertyName).GetValue(item, null);
            if (RegexPattern == null)
            {
                return (object.Equals(itemValue, Value));
            }
            else
            {
                if (itemValue is string == false)
                {
                    throw new Exception("Cannot match non-string with regex.");
                }
                else
                {
                    return Regex.Match((string)itemValue, RegexPattern).Success;
                }
            }
        }
    }
}

标记扩展是你的朋友，如果你想要做的事在XAML。

Markup extensions are your friend if you want to do something in XAML.

的（您可能要拼出来的延伸，即名称我：FilterExtension 作为上即时在Visual Studio检查没有可能会抱怨因此，它仍然编译，当然运行，但警告可能是烦人。

也不要指望 Col​​lectionViewSource.Filter 在智能感知展现出来，它不指望你通过设置XML的元素符号的处理程序）的

(You might want to spell out the name of the extension, i.e. me:FilterExtension as the on-the-fly checking in Visual Studio may complain without reason, it still compiles and runs of course but the warnings might be annoying.
Also do not expect the CollectionViewSource.Filter to show up in the IntelliSense, it does not expect you to set that handler via XML-element-notation)

这篇关于在WPF可以过滤不落后code一CollectionViewSource？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！