无绑定的ComboBox验证 [英] ComboBox Validation without Binding

问题描述

此问题基于此解决方案，但我无法使用ComboBox工作。我想验证点击提交按钮时，组合框有一个选定的项，并且不为null。请注意，我不是有意义的任何东西，而不是因为我不知道如何。但是如果答案是没有办法我可以使用验证规则没有绑定（特别是对ComboBoxes，我已经通过链接解决方案到文本框），请让我知道。

This question is based on this solution, but I somehow cannot get this to work using a ComboBox. I would like to validate that upon clicking a submit button, the combobox has a selected item and is not null. Please note that I am not binding to anything on purpose, and not because I don't know how to. But if the answer is that there is no way I can use the validation rules without binding (to ComboBoxes specifically, I've done it to textboxes via the linked solution), please let me know.

这里是我到目前为止：

XAML：

<ComboBox DataContext="{StaticResource ChargeAssigneeViewSource}" Name="ChargeAssigneeBox" ItemsSource="{Binding}" Width="85">
    <ComboBox.SelectedItem>
        <Binding RelativeSource="{RelativeSource Self}" Path="GetType" Mode="TwoWay">
            <Binding.ValidationRules>
                <my:ComboBoxValidationRule ErrorMessage="Please select an Assignee" />
            </Binding.ValidationRules>
        </Binding>
    </ComboBox.SelectedItem>
</ComboBox>

验证规则：

class ComboBoxValidationRule : ValidationRule
{
    private string errorMessage;

    public string ErrorMessage
    {
        get { return errorMessage; }
        set { errorMessage = value; }
    }
    public override ValidationResult Validate(object value, CultureInfo cultureInfo)
    {
        if (value == null)

            return new ValidationResult(false, ErrorMessage);

        return new ValidationResult(true, null);

    }
}

按钮点击：

private void AddAnHours()
    {
        Employee currEmployee;

        if (!ValidateElement.HasError(ChargeAssigneeBox))
        {
            if (!ValidateElement.HasError(analystTimeTxtBox))
            {
                currEmployee = ChargeAssigneeBox.SelectedItem as Employee;
                item.AddTime(currEmployee, DateTime.Now, double.Parse(analystTimeTxtBox.Text));
                analystTimeTxtBox.Clear();
                ChargeAssigneeBox.SelectedItem = null;
            }
        }

        UpdateTotals();

    }

我得到的错误在这行： p>

The error that I get is in this line:

currEmployee = ChargeAssigneeBox.SelectedItem as Employee;

但我的ItemsSource正在绑定，所以即使我选择了一个项目，selecteditem不转换到员工对象。我怀疑它与我绑定到它有什么关系：

but my ItemsSource is binding properly so even though I have selected an item, the selecteditem is not converting it to an employee object. I suspect it has something to do with what I am binding it to:

<Binding RelativeSoruce="{RelativeSource Self}" Path="GetType"....>

非常感谢您的帮助。

推荐答案

您不能将属性绑定到组合框上的selectedItem，然后检查该属性是否为null？

You can't bind a property to the selectedItem on the combobox and then check if thats property is null?

   Public string SelectedComboboxItem { get; set; }


     <ComboBox DataContext="{StaticResource ChargeAssigneeViewSource}"  SelectedItem="{Binding SelectedComboboxItem}" Name="ChargeAssigneeBox" ItemsSource="{Binding}" Width="85">

这篇关于无绑定的ComboBox验证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！