我遵循了 Internet 上的一些文章和教程，以便创建自定义验证属性，该属性也支持 asp.net mvc 4 网站中的客户端验证。这是我到目前为止所拥有的:

RequiredIfAttribute.cs

[AttributeUsage(AttributeTargets.Property, AllowMultiple = true)] //Added
public class RequiredIfAttribute : ValidationAttribute, IClientValidatable
{
    private readonly string condition;
    private string propertyName; //Added

    public RequiredIfAttribute(string condition)
    {
        this.condition = condition;
        this.propertyName = propertyName; //Added
    }

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        PropertyInfo propertyInfo = validationContext.ObjectType.GetProperty(this.propertyName); //Added
        Delegate conditionFunction = CreateExpression(validationContext.ObjectType, _condition);
        bool conditionMet = (bool)conditionFunction.DynamicInvoke(validationContext.ObjectInstance);

        if (conditionMet)
        {
            if (value == null)
            {
                return new ValidationResult(FormatErrorMessage(null));
            }
        }

        return ValidationResult.Success;
    }

    private Delegate CreateExpression(Type objectType, string expression)
    {
        LambdaExpression lambdaExpression = System.Linq.Dynamic.DynamicExpression.ParseLambda(objectType, typeof(bool), expression); //Added
        Delegate function = lambdaExpression.Compile();
        return function;
    }

    public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
    {
        var modelClientValidationRule = new ModelClientValidationRule
        {
            ValidationType = "requiredif",
            ErrorMessage = ErrorMessage //Added
        };

        modelClientValidationRule.ValidationParameters.Add("param", this.propertyName); //Added
        return new List<ModelClientValidationRule> { modelClientValidationRule };
    }
}

然后我将这个属性应用到类的属性中，这样

[RequiredIf("InAppPurchase == true", "InAppPurchase", ErrorMessage = "Please enter an in app purchase promotional price")] //Added "InAppPurchase"
public string InAppPurchasePromotionalPrice { get; set; }

public bool InAppPurchase { get; set; }

所以我想做的是显示一条错误消息，当 InAppPurchase 字段为真时(这意味着在表单中选中)，InAppPurchasePromotionalPrice 字段是必需的。以下是 View 的相关代码:

<div class="control-group">
                <label class="control-label" for="InAppPurchase">Does your app include In App Purchase?</label>
                <div class="controls">
                    @Html.CheckBoxFor(o => o.InAppPurchase)
                    @Html.LabelFor(o => o.InAppPurchase, "Yes")
                </div>
            </div>
            <div class="control-group" id="InAppPurchasePromotionalPriceDiv" @(Model.InAppPurchase == true ? Html.Raw("style='display: block;'") : Html.Raw("style='display: none;'"))>
                <label class="control-label" for="InAppPurchasePromotionalPrice">App Friday Promotional Price for In App Purchase: </label>
                <div class="controls">
                    @Html.TextBoxFor(o => o.InAppPurchasePromotionalPrice, new { title = "This should be at the lowest price tier of free or $.99, just for your App Friday date." })
                    <span class="help-inline">
                        @Html.ValidationMessageFor(o => o.InAppPurchasePromotionalPrice)
                    </span>
                </div>
            </div>

此代码运行良好，但当我提交表单时，服务器上会请求完整的帖子以显示消息。所以我创建了 JavaScript 代码来启用客户端验证:

requiredif.js

(function ($) {
    $.validator.addMethod('requiredif', function (value, element, params) {
        /*var inAppPurchase = $('#InAppPurchase').is(':checked');

        if (inAppPurchase) {
            return true;
        }

        return false;*/

        var isChecked = $(param).is(':checked');

        if (isChecked) {
            return false;
        }

        return true;
    }, '');

    $.validator.unobtrusive.adapters.add('requiredif', ['param'], function (options) {
        options.rules["requiredif"] = '#' + options.params.param;
        options.messages['requiredif'] = options.message;
    });
})(jQuery);

这是我在msdn和教程中找到的建议方式

当然我也插入了表单中需要的脚本:

1. jquery.unobtrusive-ajax.min.js
2. jquery.validate.min.js
3. jquery.validate.unobtrusive.min.js
4. requiredif.js

但是......客户端验证仍然不起作用。那么你能帮我找到我错过了什么吗？提前致谢。

最佳答案

看看这个:http://thewayofcode.wordpress.com/tag/custom-unobtrusive-validation/

使用本教程，我可以毫无问题地运行自定义验证代码。我可以在您的代码中发现的唯一区别是您创建 $.validator.unobtrusive.adapters.add 函数的方式。参数略有不同，但问题可能只是您没有定义适配器的 rule 部分。

尝试使用这样的东西:

$.validator.unobtrusive.adapters.add("requiredif", ["requiredif"], function (options) {
    options.rules["requiredif"] = "#" + options.params.requiredif;
    options.messages["requiredif"] = options.message;
});

或者这个

$.validator.unobtrusive.adapters.add("requiredif", function (options) {
    options.rules["requiredif"] = "#" + options.element.name.replace('.', '_'); // mvc html helpers
    options.messages["requiredif"] = options.message;
});

关于规则(取自链接):

The jQuery rules array for this HTML element. The adapter is expected to add item(s) to this rules array for the specific jQuery Validate validators that it wants to attach. The name is the name of the jQuery Validate rule, and the value is the parameter values for the jQuery Validate rule.

关于c# - 自定义验证属性中的客户端验证 - asp.net mvc 4，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19726404/