MVC：自定义属性未填充在视图中

Question

我正在编写一个自定义属性来验证名字和姓氏不超过一定数量的字符，但错误消息没有像开箱即用注释那样显示。

这是我的实现。

public class User
{
    [Required(ErrorMessage = "Last Name is required.")]
    [RegularExpression(@"^[a-zA-Z'\s]{1,50}$", ErrorMessage = "Please enter a valid last name.")]
    [FullNameMaxLength("FirstName")]
    public string LastName { get; set; }
}


public class FullNameMaxLengthAttribute : ValidationAttribute
{
    private string _firstName;

    public FullNameMaxLengthAttribute(string firstName)
    {
        _firstName = firstName;
    }
    protected override ValidationResult IsValid(object lastName, ValidationContext validationContext)
    {
        clsUserRegistration userRegistrationContext = (clsUserRegistration)validationContext.ObjectInstance;

        if (lastName != null)
        {
            string strValue = lastName.ToString();
            PropertyInfo propInfo = validationContext.ObjectType.GetProperty(_firstName);

            if (propInfo == null)
                return new ValidationResult(String.Format("Property {0} is undefined.", _firstName));

            var fieldValue = propInfo.GetValue(validationContext.ObjectInstance, null).ToString();

            if (strValue.Length + fieldValue.Length > 53)
            {
                return new ValidationResult("First and last names are too long!");
            }

            return ValidationResult.Success;
        }

        return null;
    }
}

在我看来，我有一个 ValidationMessageFor，它适用于非自定义属性。当我单步执行我的模型时，它会返回 ValidationMessage，但我看不到该错误消息。有什么想法吗？

Answer 1

以上只是“后端”验证。例如，当用户的浏览器关闭 JavaScript 时，这仍然有效 - 无论错误如何，页面都会返回，但随后会再次显示带有验证消息的表单。

对于“前端”验证，您需要以下方面的内容：

public class FullNameMaxLengthAttribute : ValidationAttribute, IClientValidatable
{
    // Your Properties and IsValid method here

    public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
    {
        var rule = new ModelClientValidationRule
        {
            ErrorMessage = String.IsNullOrEmpty(ErrorMessage) ? FormatErrorMessage(metadata.DisplayName) : ErrorMessage,
            ValidationType = "fullnamemaxlength"
        };

        rule.ValidationParameters["firstname"] = FirstName;
        rule.ValidationParameters["maxlength"] = 53;

        yield return rule;
    }
}

然后在添加到页面的 JavaScript 中：

if (jQuery.validator) {
    jQuery.validator.addMethod("fullnamemaxlength", function(value, element, param) {
    var name = param.firstname;
    var max = param.maxlength;
    return name.length > max;
});

jQuery.validator.unobtrusive.adapters.add("fullnamemaxlength", ["firstname", "maxlength"], function (options) {
        options.rules.fullnamemaxlength = {};
        options.rules.fullnamemaxlength.firstname = options.params.firstname;
        options.rules.fullnamemaxlength.maxlength = options.params.maximum;
        options.messages.fullnamemaxlength = options.message;
    }
);
}

请注意，它位于 document.ready() { }; 之外。

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