下拉式过滤器

列的下拉式过滤器允许你在运行时过滤数据。下拉式过滤器显示列的唯一值。

要过滤一列的数据，终端用户应该点击列头的过滤按钮并选择任何项目。

本节主要为大家分享自定义过滤器的示例和方法，Excel式过滤、时间下拉和常规和检查的下拉式过滤器请点击链接看官网教程。

自定义下拉式过滤器

如果你不想使用内置的下拉式过滤器，你可以自定义它或创建一个新的自定义下拉式过滤器。

这个例子显示了如何用自定义项目替换Date列的下拉过滤项目。

(全部) - 取消过滤

2008年注册 - 显示2008年注册的用户。
2009年注册用户 - 显示2009年注册的用户。

<Window x:Class="DXGrid_CustomizingFilterDropdown.Window1" 
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
        xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid"
        Title="Window1" Height="300" Width="535">
    <Grid>

        <dxg:GridControl x:Name="grid" ItemsSource="{Binding AccountList}">
            <dxg:GridControl.Columns>
                <dxg:GridColumn FieldName="UserName"/>
                <dxg:GridColumn FieldName="RegistrationDate" FilterPopupMode="List"/>
            </dxg:GridControl.Columns>
            <dxg:GridControl.View>
                <dxg:TableView AutoWidth="True" ShowFilterPopup="TableView_ShowFilterPopup" />
            </dxg:GridControl.View>
        </dxg:GridControl>
    </Grid>
</Window>

using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Documents;
using DevExpress.Data.Filtering;
using DevExpress.Xpf.Grid;

namespace DXGrid_CustomizingFilterDropdown {

    public partial class Window1 : Window {
        public Window1() {
            InitializeComponent();
            this.DataContext = new MyViewModel();

        }

        private void TableView_ShowFilterPopup(object sender, FilterPopupEventArgs e) {
            if (e.Column.FieldName != "RegistrationDate") return;
            List<object> filterItems = new List<object>();
            filterItems.Add(new CustomComboBoxItem()
            {
                DisplayValue = "(All)",
                EditValue = new CustomComboBoxItem()
            });
            filterItems.Add(new CustomComboBoxItem()
            {
                DisplayValue = "Registered in 2008",
                EditValue = CriteriaOperator.Parse(string.Format(
                "[RegistrationDate] >= #{0}# AND [RegistrationDate] < #{1}#",
                new DateTime(2008, 1, 1), new DateTime(2009, 1, 1)))
            });
            filterItems.Add(new CustomComboBoxItem()
            {
                DisplayValue = "Registered in 2009",
                EditValue = CriteriaOperator.Parse(string.Format(
                "[RegistrationDate] >= #{0}# AND [RegistrationDate] < #{1}#",
                new DateTime(2009, 1, 1), new DateTime(2010, 1, 1)))
            });
            e.ComboBoxEdit.ItemsSource = filterItems;            
        }
    }

    public class MyViewModel {
        public MyViewModel() {
            AccountList = CreateAccounts();
        }

        public List<Account> AccountList { get; set; }


        private List<Account> CreateAccounts() {
            List<Account> list = new List<Account>();
            list.Add(new Account() {
                UserName = "Nick White",
                RegistrationDate = DateTime.Today
            });
            list.Add(new Account() {
                UserName = "Jack Rodman",
                RegistrationDate = new DateTime(2009, 5, 10)
            });
            list.Add(new Account() {
                UserName = "Sandra Sherry",
                RegistrationDate = new DateTime(2008, 12, 22)
            });
            list.Add(new Account() {
                UserName = "Sabrina Vilk",
                RegistrationDate = DateTime.Today
            });
            list.Add(new Account() {
                UserName = "Mike Pearson",
                RegistrationDate = new DateTime(2008, 10, 18)
            });
            return list;
        }
    }
    public class Account {
        public string UserName { get; set; }
        public DateTime RegistrationDate { get; set; }
    }
}

如何创建一个自定义下拉式过滤器
要创建一个自定义的下拉式过滤器：

将ColumnBase.FilterPopupMode属性设置为FilterPopupMode.Custom / FilterPopupMode.ExcelSmart。
创建一个表示下拉式过滤器的模板，并将其分配给ColumnBase.CustomColumnFilterPopupTemplate属性（见示例1）。

你可以定义一个以PART_FilterElement为名的过滤器元素作为自定义数据模板（见例2）。
示例1

下面的代码示例演示了如何为Index列创建一个自定义的下拉式过滤器。

<Window x:Class="DXGrid_CustomFilterPopup.Window1" 
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid" 
    xmlns:local="clr-namespace:DXGrid_CustomFilterPopup" 
    Title="Window1" Height="300" Width="423">

    <Grid>
        <dxg:GridControl x:Name="grid">
            <dxg:GridControl.Columns>
                <dxg:GridColumn FieldName="Index" FilterPopupMode="Custom">
                    <dxg:GridColumn.CustomColumnFilterPopupTemplate>
                        <DataTemplate>
                            <StackPanel>
                            <Label Content="Minimum Index:" Margin="3" />
                            <Slider Minimum="1" Maximum="99" Width="200" Margin="3" 
                                    Value="{Binding Path=CustomColumnFilter, RelativeSource={RelativeSource TemplatedParent}, 
                                            Converter={local:IntToCriteriaOperatorConverter}}" />
                            </StackPanel>
                        </DataTemplate>
                    </dxg:GridColumn.CustomColumnFilterPopupTemplate>
                </dxg:GridColumn>
            </dxg:GridControl.Columns>
            <dxg:GridControl.View>
                <dxg:TableView AutoWidth="True" />
            </dxg:GridControl.View>
        </dxg:GridControl>
    </Grid>
</Window>

using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Markup;
using DevExpress.Data.Filtering;

namespace DXGrid_CustomFilterPopup {
    public partial class Window1 : Window {
        public Window1() {
            InitializeComponent();
            grid.ItemsSource = GridData.GetData();
        }
    }
    public class GridData {
        static public List<DataObject>  GetData() {
            List<DataObject> data = new List<DataObject>();
            for (int i = 0; i < 100; i++)
                data.Add(new DataObject() { Index = i });
            return data;
        }
    }
    public class DataObject {
        public int Index { get; set; }
    }
    public class IntToCriteriaOperatorConverter : MarkupExtension, IValueConverter {
        public override object ProvideValue(IServiceProvider serviceProvider) {
            return this;
        }
        #region IValueConverter Members
        object IValueConverter.Convert(object value, Type targetType, 
                object parameter, System.Globalization.CultureInfo culture) {
            BinaryOperator op = value as BinaryOperator;
            if (object.ReferenceEquals(op, null))
                return null;
            OperandValue operandValue = op.RightOperand as OperandValue;
            return operandValue.Value;
        }
        object IValueConverter.ConvertBack(object value, Type targetType,
                object parameter, System.Globalization.CultureInfo culture) {
            return new BinaryOperator("Index", Convert.ToInt32(value), BinaryOperatorType.Greater);
        }
        #endregion
    }
}

示例2

以下代码示例使用RangeFilterElement作为自定义数据模板。

<dxg:GridControl x:Name="grid" ItemsSource="...">
    <dxg:GridControl.Columns>
        <!-- -->
        <dxg:GridColumn FieldName="Quantity">
            <dxg:GridColumn.CustomColumnFilterPopupTemplate>
                <DataTemplate>
                    <dxfui:RangeFilterElement x:Name="PART_FilterElement"/>
                </DataTemplate>
            </dxg:GridColumn.CustomColumnFilterPopupTemplate>
        </dxg:GridColumn>
        <!-- -->
    </dxg:GridControl.Columns>
    <dxg:GridControl.View>
        <dxg:TableView ColumnFilterPopupMode="ExcelSmart" />
    </dxg:GridControl.View>
</dxg:GridControl>

下拉式过滤器

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