WPF 数据触发器和更改控件的样式

发布于 2024-08-19 14:29:29 字数 1622 浏览 2 评论 0原文

我正在使用自定义验证引擎来验证我的 ViewModel 属性。我被困在最后一步了。我想在验证失败时更改 TextBox 的背景颜色。因此，我实现了 DataTrigger 并将其绑定到 HasError 属性。 HasError 是一个普通的 CLR 属性。

  public bool HasError
        {
            get
            {
                var hasError = Errors.Count() > 0;
                return hasError;
            }
        }

代码如下：

 <Style x:Key="textBoxStyle" TargetType="{x:Type TextBox}">                   

            <Style.Triggers>

                <DataTrigger Binding="{Binding Path=HasError}" Value="True">

                    <Setter Property="Background" Value="Red" />
                </DataTrigger>          


            </Style.Triggers>

        </Style>

问题是，当将 this.DataContext 分配给视图模型时，它只会被触发一次。所以，我想也许我可以使用依赖属性而不是普通属性，但这也没有成功。

有什么想法吗？

更新：

似乎 DataTrigger 仅在挂钩到 CLR 属性而不是依赖项属性时才会触发。

更新2：

如果只有以下代码有效：

 ****<Trigger Property="{Binding Path=HasError}" Value="True">
                    <Setter Property="Background" Value="Red" />
                </Trigger>****

更新3有效：

正如答案提到的，我必须触发INotifyPropertyChanged事件。

公开可观察集合错误 { 获取 { 返回 (ObservableCollection)GetValue(ErrorsProperty); } 放 { SetValue(ErrorsProperty, 值);
 OnPropertyChanged("HasError");

        }
    }

原文

I am using my custom validation engine to validate my ViewModel properties. I am stuck at the last step. I want to change the background color of the TextBox when the validation fails. So, I implemented DataTriggers and binded it to the HasError property. HasError is a normal CLR property.

  public bool HasError
        {
            get
            {
                var hasError = Errors.Count() > 0;
                return hasError;
            }
        }

And here is the code:

 <Style x:Key="textBoxStyle" TargetType="{x:Type TextBox}">                   

            <Style.Triggers>

                <DataTrigger Binding="{Binding Path=HasError}" Value="True">

                    <Setter Property="Background" Value="Red" />
                </DataTrigger>          


            </Style.Triggers>

        </Style>

The problem is that it will be fired only once when the this.DataContext is assigned to a view model. So, I thought maybe I can use Dependency Property instead of the normal property but that did not worked out either.

Any ideas?

UPDATE:

It seems like the DataTriggers are only fired when hooked to the CLR properties and not the dependency properties.

UPDATE 2:

If only the following code worked:

 ****<Trigger Property="{Binding Path=HasError}" Value="True">
                    <Setter Property="Background" Value="Red" />
                </Trigger>****

UPDATE 3 WORKING:

As the answer mentioned I had to fire the INotifyPropertyChanged event.

public
ObservableCollection
Errors
{
get { return (ObservableCollection)GetValue(ErrorsProperty);
}
set
{
SetValue(ErrorsProperty, value);
            OnPropertyChanged("HasError");

        }
    }