用于验证的数据注释,至少一个必填字段？

Question

如果我有一个包含字段列表的搜索对象,我可以使用System.ComponentModel.DataAnnotations命名空间将其设置为验证搜索中至少有一个字段不为null或为空吗？即所有字段都是可选字段,但应始终输入至少一个字段.

Answer 1

我已经扩展了Zhaph的答案以支持属性分组.

[AttributeUsage(AttributeTargets.Class, AllowMultiple = true)]
public class AtLeastOnePropertyAttribute : ValidationAttribute
{
    private string[] PropertyList { get; set; }

    public AtLeastOnePropertyAttribute(params string[] propertyList)
    {
        this.PropertyList = propertyList;
    }

    //See http://stackoverflow.com/a/1365669
    public override object TypeId
    {
        get
        {
            return this;
        }
    }

    public override bool IsValid(object value)
    {
        PropertyInfo propertyInfo;
        foreach (string propertyName in PropertyList)
        {
            propertyInfo = value.GetType().GetProperty(propertyName);

            if (propertyInfo != null && propertyInfo.GetValue(value, null) != null)
            {
                return true;
            }
        }

        return false;
    }
}

用法:

[AtLeastOneProperty("StringProp", "Id", "BoolProp", ErrorMessage="You must supply at least one value")]
public class SimpleTest
{
    public string StringProp { get; set; }
    public int? Id { get; set; }
    public bool? BoolProp { get; set; }
}

如果你想拥有2组(或更多):

[AtLeastOneProperty("StringProp", "Id", ErrorMessage="You must supply at least one value")]
[AtLeastOneProperty("BoolProp", "BoolPropNew", ErrorMessage="You must supply at least one value")]
public class SimpleTest
{
    public string StringProp { get; set; }
    public int? Id { get; set; }
    public bool? BoolProp { get; set; }
    public bool? BoolPropNew { get; set; }
}

Answer 2

我会为此创建一个自定义验证器 - 它不会给你客户端验证,只是服务器端.

请注意,要使其正常工作,您需要使用nullable类型,因为值类型将默认为0或false:

首先创建一个新的验证器:

using System.ComponentModel.DataAnnotations;
using System.Reflection;

// This is a class-level attribute, doesn't make sense at the property level
[AttributeUsage(AttributeTargets.Class)]
public class AtLeastOnePropertyAttribute : ValidationAttribute
{
  // Have to override IsValid
  public override bool IsValid(object value)
  {
    //  Need to use reflection to get properties of "value"...
    var typeInfo = value.GetType();

    var propertyInfo = typeInfo.GetProperties();

    foreach (var property in propertyInfo)
    {
      if (null != property.GetValue(value, null))
      {
        // We've found a property with a value
        return true;
      }
    }

    // All properties were null.
    return false;
  }
}

然后你可以用这个来装饰你的模型:

[AtLeastOneProperty(ErrorMessage="You must supply at least one value")]
public class SimpleTest
{
    public string StringProp { get; set; }
    public int? Id { get; set; }
    public bool? BoolProp { get; set; }
}

然后,当您调用ModelState.IsValid验证器时,将调用您的验证器,并将您的消息添加到视图上的ValidationSummary中.

请注意,您可以扩展它以检查返回的属性类型,或者查找它们的属性以包含/排除验证(如果您愿意) - 这假设一个通用验证器不知道它验证的类型的任何内容.