如何通过不显眼的验证更改视图模型中 StringLength 属性的默认 ErrorMessage

Question

默认的 StringLength 验证错误消息对我来说太长了，所以我想缩短它。

我知道我可以为每个属性指定 ErrorMessage，但我不想到处重复：

[StringLength(25, ErrorMessage = "Max length is {1}")]
[DisplayName("Address")]
public virtual string BillAddress1 { get; set; }

基于这篇文章，Modify default ErrorMessage for StringLength validation，我将 StringLengthAttribute 子类化：

public class CustomStringLengthAttribute : StringLengthAttribute
{
    public CustomStringLengthAttribute()
        : this(20)
    {
    }

    public CustomStringLengthAttribute(int maximumLength)
        : base(maximumLength)
    {
        base.ErrorMessage = "Max length is {1}";
    }
}

并改为使用 CustomStringLengthAttribute：

[CustomStringLength(25)]
[DisplayName("Address")]
public virtual string BillAddress1 { get; set; }

这编译得很好，我在 CustomStringLengthAttribute 构造函数中设置了一个断点来验证它是否被命中，但不显眼的验证不再起作用 - 无效数据被发送回控制器。

当我不使用我的子类版本时它工作正常。

另外，这里是 javascript 验证：

if (validation.validateForm($('#addressForm'))) {
    ....
}

验证表单：

function validateForm(form) {
    prepareValidationScripts(form);
    var validator = $.data(form[0], 'validator');
    return validator.form();
}

function prepareValidationScripts(form) {
    if (form.executed)
        return;
    form.removeData("validator");
    $.validator.unobtrusive.parse(document);
    form.executed = true;
}

我错过了什么？

谢谢。

Answer 1

试试这个自定义验证。

CustomStringLengthAttribute.cs

public class CustomStringLengthAttribute : ValidationAttribute, IClientValidatable
    {
        public int MaximumLength
        {
            get;
            private set;
        }
        public int MinimumLength
        {
            get;
            set;
        }
        public CustomStringLengthAttribute(int maximumLength)
            : base(new Func<string>(CustomStringLengthAttribute.GetDefaultErrorMessage))
        {
            this.MaximumLength = maximumLength;
        }
        private static string GetDefaultErrorMessage()
        {
            return "Max length {1}";
        }
        public override string FormatErrorMessage(string name)
        {
            return string.Format(base.ErrorMessageString, name, this.MaximumLength, this.MinimumLength);
        }
        public override bool IsValid(object value)
        {
            if (value == null)
            {
                return true;
            }
            string text = (string)value;
            int maximumLength = this.MaximumLength;
            int minimumLength = this.MinimumLength;
            if (maximumLength < 0)
            {
                throw new InvalidOperationException("The maximum length must be a nonnegative integer.");
            }
            if (minimumLength > maximumLength)
            {
                throw new InvalidOperationException(string.Format("The maximum value '{0}' must be greater than or equal to the minimum value '{1}'.", maximumLength, minimumLength));
            }
            int length = text.Length;
            return length <= maximumLength && length >= minimumLength;
        }

        public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
        {
            var rule = new ModelClientValidationRule();
            rule.ErrorMessage = FormatErrorMessage(metadata.GetDisplayName());
            rule.ValidationParameters.Add("max", MaximumLength);
            rule.ValidationParameters.Add("min", MinimumLength);
            rule.ValidationType = "customstringlength";
            yield return rule;
        }
    }

在js文件中：

/// <reference path="jquery-1.4.4.js" />
/// <reference path="jquery.validate.js" />
/// <reference path="jquery.validate.unobtrusive.js" />

if ($.validator && $.validator.unobtrusive) {

    $.validator.unobtrusive.adapters.addMinMax("customstringlength", "min","max");

    $.validator.addMethod("customstringlength", function (value, element, min,max) {
        if (value) {
            if (value.length<min || value.length>max) {
                return false;
            }
        }
        return true;
    });

}

模型类：

[CustomStringLength(25)]
[DisplayName("Address")]
public virtual string BillAddress1 { get; set; }