ASP.NET中如何将单选按钮值传入数据注解参数实现字段验证

我有一组单选按钮和一个文本字段，希望选中特定的单选按钮选项（比如"Single Pdfs"）时，文本字段变为必填项。我尝试用数据注解写了自定义验证类，但没法把单选按钮的当前值传给注解参数——直接用radioButton字段会因为非静态报错，又不能把它改成静态，怕破坏其他不能修改的代码。下面是我的Model和自定义验证类代码，想问问能不能在验证类里直接获取单选按钮的字段值？

原Model代码 #

public string radioButton
{
    get => This.ArchiveFileOptions;
    set => SetProperty(This.ArchiveFileOptions, value, () =>
    {
        This.ArchiveFileOptions = value;
        ObjectState = ObjectState != ObjectStateEnum.Added ? ObjectStateEnum.Modified : ObjectStateEnum.Added;
    });
}

[IfRadioSelectedTextRequired(text: "Single Pdfs", radioValue: {{RADIO BUTTON VALUE HERE}})]
public string textField
{
    get => This.PdfIndexingRequirements;
    set => SetProperty(This.PdfIndexingRequirements, value, () => { This.PdfIndexingRequirements = value; ObjectState = ObjectState != ObjectStateEnum.Added ? ObjectStateEnum.Modified : ObjectStateEnum.Added; });
}

原自定义验证类代码 #

public class IfRadioSelectedTextRequired : ValidationAttribute
{
    private readonly string _text;
    private readonly string _radioValue;
    public IfRadioSelectedTextRequired(string text, string radioValue)
    {
        _text = text;
        _radioValue = radioValue;
    }
    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        var fieldValue = value as string;

        if (_radioValue != null)
        {
            if (_radioValue == _text)
            {
                if (fieldValue == null)
                {
                    //error
                    return new ValidationResult($"This field is required");
                }
                if (fieldValue == "")
                {
                    //error
                    return new ValidationResult($"This field is required");
                }
                if (fieldValue != null)
                {
                    //success
                    return ValidationResult.Success;
                }
            }
            if (_radioValue != _text)
            {
                //success
                return ValidationResult.Success;
            }
        }

        //success
        return ValidationResult.Success;
    }
}

数据注解的构造参数必须是编译时常量，没法直接传入实例字段的动态值，所以要修改验证逻辑，在验证时从Model实例中动态获取单选按钮的当前值：

修改后的自定义验证类 #

public class IfRadioSelectedTextRequired : ValidationAttribute
{
    // 需要触发必填的单选按钮目标值
    private readonly string _targetRadioValue;
    // Model中单选按钮字段的名称
    private readonly string _radioFieldName;

    public IfRadioSelectedTextRequired(string targetRadioValue, string radioFieldName)
    {
        _targetRadioValue = targetRadioValue;
        _radioFieldName = radioFieldName;
    }

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        // 获取当前验证的Model实例
        var model = validationContext.ObjectInstance;
        // 通过反射获取单选按钮字段的属性信息
        var radioProperty = model.GetType().GetProperty(_radioFieldName);
        
        if (radioProperty == null)
        {
            return new ValidationResult($"找不到指定的单选按钮字段：{_radioFieldName}");
        }

        // 获取单选按钮的当前值
        var radioValue = radioProperty.GetValue(model) as string;

        // 如果单选按钮选中了目标值，检查文本字段是否为空
        if (radioValue == _targetRadioValue)
        {
            var textFieldValue = value as string;
            if (string.IsNullOrWhiteSpace(textFieldValue))
            {
                return new ValidationResult("此字段为必填项");
            }
        }

        // 验证通过
        return ValidationResult.Success;
    }
}

修改后的Model用法 #

public string radioButton
{
    get => This.ArchiveFileOptions;
    set => SetProperty(This.ArchiveFileOptions, value, () =>
    {
        This.ArchiveFileOptions = value;
        ObjectState = ObjectState != ObjectStateEnum.Added ? ObjectStateEnum.Modified : ObjectStateEnum.Added;
    });
}

// 使用nameof避免硬编码字段名，更易维护
[IfRadioSelectedTextRequired(targetRadioValue: "Single Pdfs", radioFieldName: nameof(radioButton))]
public string textField
{
    get => This.PdfIndexingRequirements;
    set => SetProperty(This.PdfIndexingRequirements, value, () => 
    { 
        This.PdfIndexingRequirements = value; 
        ObjectState = ObjectState != ObjectStateEnum.Added ? ObjectStateEnum.Modified : ObjectStateEnum.Added; 
    });
}

说明 #

1. 不再通过注解参数传递单选按钮的动态值，而是传入字段名称，在验证时通过反射从Model实例中获取当前值，完美避开静态字段的限制。
2. 使用nameof(radioButton)替代硬编码字段名，后续字段名修改时编译器会自动提示，避免出错。
3. 用string.IsNullOrWhiteSpace统一判断空值和空字符串，简化逻辑。

内容的提问来源于stack exchange，提问作者tyson