c# - 空字符串的表单验证

Question

如何使表单名字输入字段不接受带有空格字符的空字符串 ""

    <form asp-action="SaveRegistration" autocomplete="off">
        <div asp-validation-summary="ModelOnly" class="text-danger"></div>
        <div class="form-group">
            <label asp-for="FirstName" class="control-label"></label>
            <input asp-for="FirstName" class="form-control" />
            <span asp-validation-for="FirstName" class="text-danger"></span>
        </div>

型号:

public class ContactInfo
{
    [Required(ErrorMessage = "This field is required")]
    [StringLength(50)]
    [DisplayName("First name")]
    public string FirstName { get; set; }
}

使用 [Required] 属性，用户仍然可以使用仅包含空格字符的字符串提交 ""

我知道这是一个简单的问题，但我是 ASP.NET MVC 的新手

Answer 1

用法:

[NotNullOrWhiteSpaceValidator]
public string FirstName { get; set; }

如何制作自己的属性:

using System;
using System.ComponentModel.DataAnnotations;

public class NotNullOrWhiteSpaceValidatorAttribute : ValidationAttribute
{
    public NotNullOrWhiteSpaceValidatorAttribute() : base("Invalid Field") { }
    public NotNullOrWhiteSpaceValidatorAttribute(string Message) : base(Message) { }

    public override bool IsValid(object value)
    {
        if (value == null) return false;

        if (string.IsNullOrWhiteSpace(value.ToString())) return false;

        return true;        
    }

    protected override ValidationResult IsValid(Object value, ValidationContext validationContext)
    {
        if (IsValid(value)) return ValidationResult.Success;
        return new ValidationResult("Value cannot be empty or white space.");
    }
}

还有更多:https://github.com/srkirkland/DataAnnotationsExtensions/tree/master/DataAnnotationsExtensions