DataGridTextColum绑定StringFormat [英] DataGridTextColum binding StringFormat

问题描述

我试图将视图模型中的字符串绑定到DataGridTextColumn的StringFormat属性.但是，我下面的内容不起作用.有没有办法在不使用转换器或资源的情况下做到这一点?如果没有，最简单的方法是什么?

I am trying to bind a string in my view model to the StringFormat property of the DataGridTextColumn. But, what I have below is not working. Is there a way to do this without using converters or resources? If not, what's the easiest way to do it?

<DataGridTextColumn Binding="{Binding Date, StringFormat={Binding DateFormat}}" />

推荐答案

您不能将任何内容绑定到 Binding 的属性，因为 Binding 类不继承自 DependencyObject .

You can't bind anything to properties of Binding because the Binding class doesn't inherit from DependencyObject.

控件具有您可以绑定的 ContentStringFormat 属性.如果 DataGridTextColumn 是从 ContentControl 派生的，那将解决您的问题，但事实并非如此.

Controls derived from ContentControl (e.g. Label) have a ContentStringFormat property that you can bind. That would solve your problem in this case if DataGridTextColumn were derived from ContentControl but it isn't.

您可以将其设置为带有包含 Label 的 DataTemplate 的 DataGridTemplateColumn ，然后将 Label.ContentStringFormat 绑定到您的 DateFormat 属性:

You could make it a DataGridTemplateColumn with a DataTemplate containing a Label, and bind Label.ContentStringFormat to your DateFormat property:

<DataGridTemplateColumn Header="Date Template">
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <Label
                Content="{Binding Date}"
                ContentStringFormat="{Binding DataContext.DateFormat, 
                    RelativeSource={RelativeSource AncestorType=DataGrid}}"
                />
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>

但是当我更改viewmodel的 DateFormat 属性时，这不会更新.我不知道为什么不这样做，可能是我做错了.

But that doesn't update when I change the viewmodel's DateFormat property. I don't know why not, possibly I did something wrong.

这给我们留下了一个多值转换器.当我更改viewmodel的 DateFormat 属性(两个相邻的列，一个更新而另一列没有更新)时，该更新确实会更新-所以没有人告诉我我没有提出 PropertyChanged ).

That leaves us with a multi-value converter. That does update when I change the viewmodel's DateFormat property (two adjacent columns, one updates and the other doesn't -- so don't anybody tell me I didn't raise PropertyChanged).

<Window.Resources>
    <local:StringFormatConverter x:Key="StringFormatConverter" />
</Window.Resources>

...等等等等...

...blah blah blah...

<DataGridTextColumn
    Header="Date Text" 
    >
    <DataGridTextColumn.Binding>
        <MultiBinding Converter="{StaticResource StringFormatConverter}">
            <Binding Path="Date" />
            <Binding 
                Path="DataContext.DateFormat" 
                RelativeSource="{RelativeSource AncestorType=DataGrid}" />
        </MultiBinding>
    </DataGridTextColumn.Binding>
</DataGridTextColumn>

C#:

这会将任何字符串格式应用于任何值，而不仅仅是 DateTime .我的 DateFormat 属性返回的是"{0:yyyy-MM-dd}" .

This will apply any string format to any value, not just a DateTime. My DateFormat property is returning "{0:yyyy-MM-dd}".

此转换器上的第一个绑定是您要格式化的值.

The first binding on this converter is the value you want to format.

第二个绑定是 {0} -并且，如果该值为 DateTime ，则将其格式化为四个位数年份，破折号，两位数的月份，破折号和两位数的日期. DateTime 格式字符串本身是一个主题；这是该主题上的MSDN页面.

The second binding is a format string parameter for String.Format(). The above format string takes the "zeroth" parameter after the format string -- that's {0} -- and, if that value is a DateTime, formats it with a four digit year, a dash, a two digit month, a dash, and a two digit day. DateTime format strings are a subject unto themselves; here's the MSDN page on the subject.

我给你的东西是最简单的写方法，而最强大的就是它.您可以传入一个双精度型，并给它一个格式字符串，例如我的演员表有{0:c}脚趾" ，如果双精度型是 3.00999 ，它会告诉您它的猫的脚趾 $ 3.01 .

What I've given you is the simplest way to write this, and by a vast margin the most powerful. You can pass in a double and give it a format string like "My cast has {0:c} toes" and if the double is 3.00999, it'll tell you its cat has $3.01 toes.

但是，在为您提供 String.Format()的全部功能时，我使编写格式字符串的业务变得有些复杂.这是一个权衡.

However, in giving you all the power of String.Format(), I've somewhat complicated the business of writing your format strings. It's a tradeoff.

public class StringFormatConverter : IMultiValueConverter
{
    public object Convert(object[] values, 
        Type targetType, object parameter, CultureInfo culture)
    {
        return String.Format((String)values[1], values[0]);
    }

    public object[] ConvertBack(object value, 
        Type[] targetTypes, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

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