Question

假设我有一个绑定到DateTime的TextBlock，有没有办法用空字符串替换值0001-01-01 00:00:00？

Answer 1

您有几个选择：

绑定到DateTime?（即Nullable<DateTime>）而不是DateTime。如果您不想显示任何内容，请将值设置为null。
绑定到您的视图模型上的单独属性，该属性负责将DateTime.MinValue转换为空string。
直接绑定到DateTime属性并使用转换器将DateTime.MinValue转换为空string。

＃1的示例

<TextBlock Text="{Binding SomeDateTime}"/>

public class YourViewModel : ViewModel
{
    private DateTime? _someDateTime;

    public DateTime? SomeDateTime
    {
        get { return _someDateTime; }
        set
        {
            if (_someDateTime != value)
            {
                _someDateTime = value;
                OnPropertyChanged("SomeDateTime");
            }
        }
    }
}

＃2的例子

<TextBlock Text="{Binding SomeDateTimeString}"/>

public class YourViewModel : ViewModel
{
    private DateTime _someDateTime;

    public DateTime SomeDateTime
    {
        get { return _someDateTime; }
        set
        {
            if (_someDateTime != value)
            {
                _someDateTime = value;
                OnPropertyChanged("SomeDateTime");
                OnPropertyChanged("SomeDateTimeString");
            }
        }
    }

    public string SomeDateTimeString
    {
        get { return SomeDateTime == DateTime.MinValue ? "" : SomeDateTime; }
    }
}

＃3的例子

<!-- in resources -->
<local:DateTimeConverter x:Key="YourConverter"/>

<TextBlock Text="{Binding SomeDateTime, Converter={StaticResource YourConverter}}"/>

public class YourClass
{
    private DateTime _someDateTime;

    public DateTime SomeDateTime
    {
        get { return _someDateTime; }
        set
        {
            if (_someDateTime != value)
            {
                _someDateTime = value;
                OnPropertyChanged("SomeDateTime");
            }
        }
    }
}

public class DateTimeConverter : IValueConverter
{
    public object Convert(object value ...)
    {
        return value == DateTime.MinValue ? "" : value;
    }

    ...
}

Answer 2

使用转换器格式化日期

转换代码：

public class MyDateConverter : IValueConverter
{

    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {    
        DateTime dt = (DateTime)value;
        if (dt == dt.MinValue)
            return "";
        else
            return dt.ToString();
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {    
        string s = (string)value;
        if (string.IsNullOrEmpty(s))
            return DateTime.MinValue;
        else
            return DateTime.Parse(s);
    }
}

XAML：

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

...

<TextBlock Text="{Binding TheDate, Converter={StaticResource dateConverter}}"/>

WPF替换TextBlock中的值

2 个答案: