Question

我对ComboBox上的绑定有问题，我不明白为什么它不起作用：

以下代码绑定对象上的项目，它完美地运行：

<ComboBox Grid.Row="4" Grid.Column="2" Name="comboBoxDefinedBy" Style="{StaticResource ComboBoxStandard}" Margin="0,0,5,0" ItemTemplate="{StaticResource DealerTemplateComboBox}"  SelectedValue="{Binding DefinedBy_Id, Mode=TwoWay}" SelectedValuePath="Id">                
</ComboBox>

以下不起作用，验证规则完美运行：

<ComboBox Grid.Row="4" Grid.Column="2" Name="comboBoxDefinedBy" Style="{StaticResource ComboBoxStandard}" Margin="0,0,5,0" ItemTemplate="{StaticResource DealerTemplateComboBox}"  SelectedValuePath ="DefinedBy_Id">
    <ComboBox.SelectedItem>
        <Binding Path="Id" UpdateSourceTrigger="PropertyChanged" Mode="TwoWay">
            <Binding.ValidationRules>
                <customValidationRules:ComboBoxIsNotEmptyValidationRule></customValidationRules:ComboBoxIsNotEmptyValidationRule>
            </Binding.ValidationRules>
        </Binding>
    </ComboBox.SelectedItem>
</ComboBox>

Answer 1

正如article所说，你有几个选择。

您可以将SelectedItem绑定到某个媒体资源，然后对此进行验证

private MyDataObject _someData;
public MyDataObject SomeData
{
    get
    {
        return _ someData;
    }
    set
    {
        _ someData = value;
        if (value == null || string.IsNullOrEmpty(value.MyProperty))
            throw new ApplicationException("SomeData is required");
    }
}

<ComboBox.SelectedItem>
    <Binding Path="SomeData" ElementName="Window">
        <Binding.ValidationRules>
            <ExceptionValidationRule />
        </Binding.ValidationRules>
    </Binding>
</ComboBox.SelectedItem>

或者，您可以创建自己的验证规则，然后像这样执行

public class MyCustomValidationRule : ValidationRule
{
    public override ValidationResult Validate(object value, CultureInfo cultureInfo)
    {
        if (value is MyDataObject)
        {
            var myDataObj = (MyDataObject)value;
            if (myDataObj.CheckCustomBusinessRules())
                return new ValidationResult(true, null);
        }

        return new ValidationResult(false, "Invalid selection!");
    }
}

<ComboBox.SelectedItem>
    <Binding Path="SomeData" ElementName="Window">
        <Binding.ValidationRules>
            <local:PersonValidation />
        </Binding.ValidationRules>
    </Binding>
</ComboBox.SelectedItem>

进一步采取这一步骤，正如question建议的那样，将ValidationRules替换为IDataErrorInfo之类的内容。这个article很好地概述了验证的不同方法。

Combobox绑定验证规则

1 个答案: