c# – WPF不绑定ComboBox SelectedItem
发布时间：2020-12-15 18:36:29 所属栏目：百科 来源：网络整理
导读：我已经广泛搜索,但我找不到任何解决方案. 我在我的项目中有几个ComboBox,我正在寻找一个自动完成解决方案,然后我发现了一个很好的并应用于我的项目,我将解决方案的样式也应用到我项目中的所有ComboBox. 在那之后,SelectedItem停止了工作,有人可以帮助我吗？
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我已经广泛搜索,但我找不到任何解决方案.
我在我的项目中有几个ComboBox,我正在寻找一个自动完成解决方案,然后我发现了一个很好的并应用于我的项目,我将解决方案的样式也应用到我项目中的所有ComboBox. 在那之后,SelectedItem停止了工作,有人可以帮助我吗？ 我的组合框： <ComboBox Name="CbOwnerType" Grid.Column="1" Grid.Row="2" ItemsSource="{Binding Path=OwnerTypes,Mode=OneWay}" SelectedItem="{Binding Owner.OwnerType,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" SelectedValuePath="Id" DisplayMemberPath="Name" Margin="5,10,0" />
我的风格： <Style TargetType="{x:Type ComboBox}">
<Setter Property="FocusVisualStyle" Value="{x:Null}" />
<Setter Property="Foreground" Value="Black" />
<Setter Property="FontWeight" Value="ExtraBold" />
<Setter Property="IsEditable" Value="False"/>
<Setter Property="IsSynchronizedWithCurrentItem" Value="False" />
<Setter Property="StaysOpenOnEdit" Value="True" />
<Setter Property="SnapsToDevicePixels" Value="True"/>
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.CanContentScroll" Value="true"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid>
<ToggleButton Name="ToggleButton" Template="{StaticResource ComboBoxToggleButton}" Grid.Column="2" Focusable="True" IsChecked="{Binding Path=IsDropDownOpen,RelativeSource={RelativeSource TemplatedParent}}" ClickMode="Press" BorderThickness="0" />
<ContentPresenter Name="ContentSite" IsHitTestVisible="False" Content="{TemplateBinding SelectionBoxItem}" ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}" ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}" Margin="5,20,0" VerticalAlignment="Center" HorizontalAlignment="Left" />
<TextBox x:Name="PART_EditableTextBox" Style="{x:Null}" Template="{StaticResource ComboBoxTextBox}" HorizontalAlignment="Left" VerticalAlignment="Bottom" Margin="3,3,23,3" Focusable="True" Background="Transparent" Visibility="Hidden" IsReadOnly="{TemplateBinding IsReadOnly}" />
<Popup Name="Popup" Placement="Bottom" IsOpen="{TemplateBinding IsDropDownOpen}" AllowsTransparency="True" Focusable="False" PopupAnimation="Slide">
<Themes:SystemDropShadowChrome Margin="4,6,4,6" CornerRadius="4">
<Grid Name="DropDown" SnapsToDevicePixels="True" MinWidth="{TemplateBinding ActualWidth}" MaxHeight="{TemplateBinding MaxDropDownHeight}">
<Border x:Name="DropDownBorder" Background="{StaticResource WindowBackgroundBrush}" BorderThickness="1" BorderBrush="{StaticResource SolidBorderBrush}" />
<ScrollViewer Margin="4,6" SnapsToDevicePixels="True">
<ItemsPresenter />
</ScrollViewer>
</Grid>
</Themes:SystemDropShadowChrome>
</Popup>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="HasItems" Value="false">
<Setter TargetName="DropDownBorder" Property="MinHeight" Value="95"/>
</Trigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}"/>
</Trigger>
<Trigger Property="IsGrouping" Value="true">
<Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
</Trigger>
<Trigger SourceName="Popup" Property="Popup.AllowsTransparency" Value="true">
<Setter TargetName="DropDownBorder" Property="CornerRadius" Value="4"/>
<Setter TargetName="DropDownBorder" Property="Margin" Value="0,2,0"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
UPDATE 我的ToggleButton <ControlTemplate x:Key="ComboBoxToggleButton" TargetType="{x:Type ToggleButton}" >
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition Width="20" />
</Grid.ColumnDefinitions>
<Border x:Name="Border" Grid.ColumnSpan="2" BorderBrush="{StaticResource LabPetsStandardColor}" BorderThickness="1" CornerRadius="5" />
<Border Grid.Column="0" Margin="1" Background="Transparent" BorderBrush="{StaticResource NormalBorderBrush}" BorderThickness="0" CornerRadius="5,5" />
<Path x:Name="Arrow" Grid.Column="1" HorizontalAlignment="Center" VerticalAlignment="Center" Data="M 0 0 L 4 4 L 8 0 Z">
<Path.Fill>
<SolidColorBrush Color="Black" />
</Path.Fill>
</Path>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="ToggleButton.IsMouSEOver" Value="true">
<Setter TargetName="Border" Property="Background" Value="{StaticResource LabPetsStandardColor}" />
</Trigger>
<Trigger Property="ToggleButton.IsChecked" Value="true">
<Setter TargetName="Border" Property="Background" Value="{StaticResource LabPetsPressedStandardColor}" />
</Trigger>
<Trigger Property="IsEnabled" Value="False">
<Setter TargetName="Border" Property="Background" Value="{StaticResource DisabledBackgroundBrush}" />
<Setter TargetName="Border" Property="BorderBrush" Value="{StaticResource DisabledBorderBrush}" />
<Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}"/>
<Setter TargetName="Arrow" Property="Fill" Value="{StaticResource DisabledForegroundBrush}" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
我的TextBox <Style x:Key="ComboBoxTextBox" TargetType="{x:Type TextBox}">
<Setter Property="OverridesDefaultStyle" Value="True" />
<Setter Property="AllowDrop" Value="True" />
<Setter Property="MinWidth" Value="0" />
<Setter Property="MinHeight" Value="0" />
<Setter Property="FocusVisualStyle" Value="{x:Null}" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TextBox}">
<ScrollViewer HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Hidden" Background="#00FFFFFF" Name="PART_ContentHost" Focusable="False" VerticalAlignment="Center" VerticalContentAlignment="Center" Margin="0">
<ScrollViewer.Style>
<Style TargetType="ScrollViewer">
<Setter Property="OverridesDefaultStyle" Value="True" />
</Style>
</ScrollViewer.Style>
</ScrollViewer>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
请帮助我一些？ 更新2 找到了一个黑客,不是完美的解决方案,而是一种有效的工作…… 如果我插入属性SelectedValue和值Owner.OwnerTypeId,它就像一个魅力…但是,这是正确的吗？ 我的Combobox现在： <ComboBox Name="CbOwnerType" Grid.Column="1" Grid.Row="2" ItemsSource="{Binding Path=OwnerTypes,Mode=OneWay}" SelectedItem="{Binding Owner.OwnerType}" SelectedValue="{Binding Owner.OwnerTypeId}" SelectedValuePath="Id" DisplayMemberPath="Name" Margin="5,0" />
这是一个解决方案,不是我喜欢它,但它是一个解决方案…… Obs.：当我更改选择时,SelectedItem工作,只是在我加载视图时不起作用. 更新3 好吧,它像我说的那样工作,但问题是WPF在我的ViewModel上打了4次,所以我改变了我的ComboBox： <ComboBox Name="CbOwnerType" Grid.Column="1" Grid.Row="2" ItemsSource="{Binding Path=OwnerTypes,Mode=OneWay}" SelectedItem="{Binding Owner.OwnerType}" SelectedValue="{Binding Owner.OwnerTypeId,Mode=OneTime}" SelectedValuePath="Id" DisplayMemberPath="Name" Margin="5,0" />
所以,现在,WPF只搜索OwnerTypeId,当我更改项目时,WPF只会命中2次. 更新4 好的,另一个奇怪的发现…… 更新5 对不起,我忘记发布我的模特了. 型号所有者： public class Owner
{
public int Id { get; set; }
public int OwnerTypeId { get; set; }
public string Name { get; set; }
public string Address { get; set; }
public string FormatedPhone
{
get
{
if (this.Phone == null)
return string.Empty;
switch (this.Phone.Length)
{
case 11:
return Regex.Replace(this.Phone,@"(d{2})(d{4})(d{4})","($1) $2-$3");
case 12:
return Regex.Replace(this.Phone,@"(d{2})(d{5})(d{4})","($1) $2-$3");
default:
return this.Phone;
}
}
}
public string Phone { get; set; }
public string CellPhone { get; set; }
public string FormatedCellPhone
{
get
{
if (this.CellPhone == null)
return string.Empty;
switch (this.CellPhone.Length)
{
case 11:
return Regex.Replace(this.Phone,"($1) $2-$3");
default:
return this.CellPhone;
}
}
}
public string Email { get; set; }
public virtual OwnerType OwnerType { get; set; }
public virtual ICollection<Animal> Animals { get; set; }
public Owner()
{
this.OwnerType = new OwnerType();
this.Animals = new List<Animal>();
this.ErrorList = new StringBuilder();
}
型号所有者类型： public class OwnerType
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<Owner> Owners { get; set; }
public OwnerType()
{
this.Owners = new List<Owner>();
}
}
解决方法
您的SelectedItem绑定不起作用,因为WPF通过.Equals()方法将SelectedItem与ItemsSource中的项进行比较,默认情况下,通过引用进行比较.包含SelectedItem的内存中的实例与ItemsSource中的项目之一在内存中不是同一个实例
有3种方法可以解决这个问题. >首先,您已经发现可以将SelectedValue绑定到项目的值类型属性,并设置SelectedValuePath. <ComboBox ItemsSource="{Binding Path=OwnerTypes}"
SelectedValue="{Binding Owner.OwnerTypeId}"
SelectedValuePath="Id" DisplayMemberPath="Name"
/>
这通常是我使用的解决方案,因为它通常是最简单的 public class Owner()
{
public int OwnerTypeId { get; set; }
public OwnerType OwnerType
{
get
{
return StaticClass.OwnerTypes
.FirstOrDefault(p => p.Id == this.OwnerTypeId);
}
set
{
if (value != null)
OwnerTypeId = value.Id;
}
}
}
>最后,您可以覆盖OwnerType对象上的.Equals()方法,以便在Id属性相同时将两个值视为相等. public override bool Equals(object obj)
{
if (obj == null || !(obj is OwnerType))
return false;
return ((OwnerType)obj).Id == this.Id);
}
我通常会尝试避免使用此方法,除非我知道我总是希望仅通过Id属性来比较此对象的相等性,但有时这是最好的方法. 此外,每当你覆盖.Equals()时,它的优良做法是覆盖.GetHashCode(). 作为旁注,您通常不希望绑定SelectedItem和SelectedValue.它们是设置相同内容的两种不同方式,您可以通过绑定它们来获得意外结果. （编辑：李大同） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |