Can I do Text search with multibinding

问题:

I have below combo box in mvvm-wpf application. I need to implement "Text search" in this..(along with multibinding). Can anybody help me please.

<StackPanel Orientation="Horizontal">
    <TextBlock Text="Bid Service Cat ID"
                Margin="2"></TextBlock>
    <ComboBox Width="200"
                Height="20"
                SelectedValuePath="BidServiceCategoryId"
                SelectedValue="{Binding RelativeSource={RelativeSource AncestorType={x:Type UserControl}},
                    Path=DataContext.SelectedBidServiceCategoryId.Value}"
                ItemsSource="{Binding RelativeSource={RelativeSource AncestorType={x:Type UserControl}},
                    Path=DataContext.BenefitCategoryList}"
                Margin="12,0">
        <ComboBox.ItemTemplate>
            <DataTemplate>
                <TextBlock DataContext="{Binding}">
                            <TextBlock.Text>
                                <MultiBinding StringFormat="{}{0}: {1}">
                                <Binding Path="BidServiceCategoryId" />
                                <Binding Path="BidServiceCategoryName" />
                            </MultiBinding>
                            </TextBlock.Text></TextBlock>
            </DataTemplate>
        </ComboBox.ItemTemplate>
    </ComboBox>
</StackPanel>

回答1:

Unfortunately, TextSearch.Text doesn't work in a DataTemplate. Otherwise you could have done something like this

<ComboBox ...>
    <ComboBox.ItemContainerStyle>
        <Style TargetType="{x:Type ComboBoxItem}">
            <Setter Property="TextSearch.Text">
                <Setter.Value>
                    <MultiBinding StringFormat="{}{0}: {1}">
                        <Binding Path="BidServiceCategoryId"/>
                        <Binding Path="BidServiceCategoryName"/>
                    </MultiBinding>
                </Setter.Value>
            </Setter>
        </Style>
    </ComboBox.ItemContainerStyle>
</ComboBox>

However this won't work, so I see two solutions to your problem.

First way
You set IsTextSearchEnabled to True for the ComboBox, override ToString in your source class and change the MultiBinding in the TextBlock to a Binding

Xaml

<ComboBox ...
          IsTextSearchEnabled="True">
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding}"/>
        </DataTemplate>
    </ComboBox.ItemTemplate>

Source class

public class TheNameOfYourSourceClass
{
    public override string ToString()
    {
        return String.Format("{0}: {1}", BidServiceCategoryId, BidServiceCategoryName);
    }
    //...
}

---

Second Way
If you don't want to override ToString I think you'll have to introduce a new Property in your source class where you combine BidServiceCategoryId and BidServiceCategoryName for the TextSearch.TextPath. In this example I call it BidServiceCategory. For this to work, you'll have to call OnPropertyChanged("BidServiceCategory"); when BidServiceCategoryId or BidServiceCategoryName changes as well. If they are normal CLR properties, you can do this in set, and if they are dependency properties you'll have to use the property changed callback

Xaml

<ComboBox ...
          TextSearch.TextPath="BidServiceCategory"
          IsTextSearchEnabled="True">
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <TextBlock DataContext="{Binding}">
                <TextBlock.Text>
                    <MultiBinding StringFormat="{}{0}: {1}">
                        <Binding Path="BidServiceCategoryId" />
                        <Binding Path="BidServiceCategoryName" />
                    </MultiBinding>
                </TextBlock.Text>
            </TextBlock>
        </DataTemplate>
    </ComboBox.ItemTemplate>

Source class

public class TheNameOfYourSourceClass
{
    public string BidServiceCategory
    {
        get
        {
            return String.Format("{0}: {1}", BidServiceCategoryId, BidServiceCategoryName);
        }
    }

    private string m_bidServiceCategoryId;
    public string BidServiceCategoryId
    {
        get
        {
            return m_bidServiceCategoryId;
        }
        set
        {
            m_bidServiceCategoryId = value;
            OnPropertyChanged("BidServiceCategoryId");
            OnPropertyChanged("BidServiceCategory");
        }
    }

    private string m_bidServiceCategoryName;
    public string BidServiceCategoryName
    {
        get
        {
            return m_bidServiceCategoryName;
        }
        set
        {
            m_bidServiceCategoryName = value;
            OnPropertyChanged("BidServiceCategoryName");
            OnPropertyChanged("BidServiceCategory");
        }
    }
}

回答2:

I don't know if your text search has to search ALL the text, but if you want to search from the category ID, you can just set the TextSearch.TextPath property to BidServiceCategoryId. That should also be helpful for anyone who wants to use multibinding and finds that the text search no longer works... It does work if you explicitly set the TextPath property.