c# - MVC.NET Core 中的条件验证 (RequiredIf)

Question

我正在尝试有条件地验证 MVC.NET Core 中的字段。我有两个单选按钮。如果我选择是(对于所有权)，我想在下方创建一个必填字段(事件下拉列表)

但是，无论我多么努力，要验证的值始终来自 Activity 字段，而不是 Ownership 字段(“N\A”而不是“Yes”)

谁能告诉我我做错了什么

View (chtml)

<div class=" form-group">
    <div class="bisformdynamiclabel"></div>
    <br />
    @Html.RadioButtonFor(model => model.BIS232Request.JSONData.OwnershipActivity.Ownership, "Yes", new { id = "OwnershipAnswer_true", onclick = "displayOwnershipFieldsRow(true)" })
    <label for="OwnershipAnswer_true">Yes</label>
    @Html.RadioButtonFor(model => model.BIS232Request.JSONData.OwnershipActivity.Ownership, "No", new { id = "OwnershipAnswer_false", onclick = "displayOwnershipFieldsRow(false)" })
    <label for="OwnershipAnswer_false">No</label>
    <span class="alert-danger">
        @Html.ValidationMessage("OwnershipAnswer")
    </span>
</div>
<div class="row ownershipfieldsrow">
    <div class="col-xs-12 col-md-12">
        <div class=" form-group">
            <div class="bisformdynamiclabel"></div>
            <br />
            <input style="display:none" class="form-control" type="text" asp-for="BIS232Request.JSONData.OwnershipActivity.Activity" />
            <select class="form-control ownershipactivityselect" onchange="$('#BIS232Request_JSONData_OwnershipActivity_Activity').val($(this).val());  ">
                <option value="N/A">Please Select</option>
                <option value="Manufacturer">Manufacturer</option>
                <option value="Distributor">Distributor</option>
                <option value="Exporter">Exporter</option>
                <option value="Importer">Importer</option>
                <option value="Other">Other</option>
            </select>
            <span asp-validation-for="BIS232Request.JSONData.OwnershipActivity.Activity" class="alert-danger"></span>
            <span class="alert-danger">
                @Html.ValidationMessage("OwnershipAnswerActivity")
            </span>
        </div>
    </div>

模型

[Required]
public string Ownership { get; set; }
[RequiredIf("Ownership", "OwnershipAnswer_true", "Activity is required if Ownership is selected")]
public string Activity { get; set; }        
public class RequiredIfAttribute : ValidationAttribute
{
    private String PropertyName { get; set; }
    private String ErrorMessage { get; set; }
    private Object DesiredValue { get; set; }

    public RequiredIfAttribute(String propertyName, Object desiredvalue, String errormessage)
    {
        this.PropertyName = propertyName;
        this.DesiredValue = desiredvalue;
        this.ErrorMessage = errormessage;
    }

    protected override ValidationResult IsValid(object value, ValidationContext context)
    {
        Object instance = context.ObjectInstance;
        Type type = instance.GetType();
        Object proprtyvalue = type.GetProperty(PropertyName).GetValue(instance, null);
        if (proprtyvalue.ToString() == DesiredValue.ToString() && value == null)
        {
            return new ValidationResult(ErrorMessage);
        }
        return ValidationResult.Success;
    }
}

Answer 1

基于最初的实现，我建议扩展 RequiredAttribute 而不是 ValidationAttribute - 然后您的默认 ErrorMessage 和其他默认设置按照 [Required] 设置。无论哪种方式，“errormessage”属性都是多余的，因为您已经将其作为 ValidationAttribute 的属性，并且原始代码会为 ErrorMessage 属性生成警告 - 您也可以使用 nameof 用于属性装饰以及使代码中的内容更紧凑:

我的实现稍微更具体一些，因此如果属性是 bool，我可以指示属性是必需的(如果选中复选框):

[AttributeUsage(AttributeTargets.Property)]
public class RequiredIfTrueAttribute : RequiredAttribute
{
    private string PropertyName { get; set; }

    public RequiredIfTrueAttribute(string propertyName)
    {
        PropertyName = propertyName;
    }

    protected override ValidationResult IsValid(object value, ValidationContext context)
    {
        object instance = context.ObjectInstance;
        Type type = instance.GetType();

        bool.TryParse(type.GetProperty(PropertyName).GetValue(instance)?.ToString(), out bool propertyValue);

        if (propertyValue && string.IsNullOrWhiteSpace(value?.ToString()))
        {
            return new ValidationResult(ErrorMessage);
        }

        return ValidationResult.Success;
    }
}

示例用法:

public bool IsBusinessProfile { get; set; }

[RequiredIfTrue(nameof(IsBusinessProfile), ErrorMessage = "ABN is required for Business Profiles")]
public string Abn { get; set; }