用于唯一字段的WPF DataGrid验证规则 [英] Wpf datagrid validationrule for unique field

问题描述

我有一个名为UniqueNameSolidWoodRule的经过分类的ValidationRule，用于验证数据网格中的重复条目。

I've got a suclassed ValidationRule named UniqueNameSolidWoodRule to validate for duplicate entries in a datagrid.

这里是代码：

public class UniqueNameSolidWoodRule : ValidationRule
{
    public CollectionViewSource CurrentCollection { get; set; }

    public override ValidationResult Validate(object value, CultureInfo cultureInfo)
    {
        if (value != null)
        {
            ObservableCollection<SolidWood_VM> castedCollection = (ObservableCollection<SolidWood_VM>)CurrentCollection.Source;

            foreach (SolidWood_VM swVM in castedCollection)
            {
                if (swVM.Designation == value.ToString())
                {
                    return new ValidationResult(false, ResourcesManager.Instance.GetString("DuplicatedRecord"));
                }
            }
        }

        return new ValidationResult(true, null);
    }
}

这是XAML代码段：

<DataGrid.Resources>
        <CollectionViewSource x:Key="CurrentSolidWoodCollection" Source="{Binding Path=SolidWoods}" />
</DataGrid.Resources>

 <DataGridTextColumn x:Name="Column2" Header="{x:Static p:Resources.Designation}" Width="auto">
        <DataGridTextColumn.Binding>
            <Binding Path="Designation" ValidatesOnDataErrors="True" UpdateSourceTrigger="LostFocus">
                 <Binding.ValidationRules>
                        <my:UniqueNameSolidWoodRule  CurrentCollection="{StaticResource CurrentSolidWoodCollection}"/>
                  </Binding.ValidationRules>
             </Binding>
         </DataGridTextColumn.Binding>
  </DataGridTextColumn>

我的问题是有时该规则会将值与自己的行进行比较。我该如何预防？在我看来，我需要与该值关联的row.index属性进行比较，但不幸的是，我无法找到一种方法来实现此目的。

My problem is that sometimes this rule compares the value with its own row. How could I prevent this? It seems to me that I need a row.index property associated with the value to compare, but unfortunnally I can't figure a way out to achieve this.

推荐答案

我终于可以正常工作了！

I finally got things working!

这是解决方案：

在XAML中，我添加了以下ValidationStep：

In the XAML I added the following ValidationStep:

<my:UniqueNameSolidWoodRule CurrentCollection="{StaticResource CurrentSolidWoodCollection}" ValidationStep="CommittedValue"/>

这样，我得到了BindingExpression对象而不是字符串，作为覆盖的Validate的第一个参数方法，该方法为我提供了有关验证记录的更多信息，例如 HashCode ，我可以用来检查是否在比较同一对象。

This way I'm getting a BindingExpression object instead of a string as the first parameter of the overridden Validate method, which gives me much more information about the record to validate like the HashCode I can use to check if I'm comparing the same object.

这是更新的Validate方法：

Here's the updated Validate method:

public class UniqueNameSolidWoodRule : ValidationRule
{
    public CollectionViewSource CurrentCollection { get; set; }

    public override ValidationResult Validate(object value, CultureInfo cultureInfo)
    {
        if (value != null)
        {
            ObservableCollection<SolidWood_VM> castedCollection = (ObservableCollection<SolidWood_VM>)CurrentCollection.Source;

            SolidWood_VM curValue = (SolidWood_VM)((BindingExpression)value).DataItem;

            foreach (SolidWood_VM swVM in castedCollection)
            {
                if (curValue.GetHashCode() != swVM.GetHashCode() && swVM.Designation == curValue.Designation.ToString())
                {
                    return new ValidationResult(false, ResourcesManager.Instance.GetString("DuplicatedRecord"));
                }
            }
        }

        return new ValidationResult(true, null);
    }
}

这篇关于用于唯一字段的WPF DataGrid验证规则的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！