c# – 如何直接对List进行验证？

我有一个模型类：

public class MyModel() { //properties here... }

我想验证一个MyModel对象列表.所以我创建了这个验证器：

class MyModelListValidator : AbstractValidator<List<MyModel>>
{
    public MyModelListValidator ()
    {
        RuleFor(x => x)
            .SetCollectionValidator(new MyModelValidator())
            .When(x => x != null);
    }

    private class MyModelValidator : AbstractValidator<MyModel>
    {
        public MyModelValidator()
        {
            //MyModel property validation here...
        }
    }
}

但上述方法无效.另一种方法是创建一个类,如：

public class MyModelList()
{
    public List<MyModel> Items { get; set; }
}

这会奏效.

但有没有办法在不使用这个额外的类的情况下做到这一点？

解决方法

如果您使用数据批注来执行验证,则可能需要自定义属性：

public class EnsureOneElementAttribute : ValidationAttribute
{
    public override bool IsValid(object value)
    {
        var list = value as IList;
        if (list != null)
        {
            return list.Count > 0;
        }
        return false;
    }
}

然后：

[EnsureOneElement(ErrorMessage = "At least a person is required")]
public List<Person> Persons { get; private set; }
or to make it more generic:

public class EnsureMinimumElementsAttribute : ValidationAttribute
{
    private readonly int _minelements;
    public EnsureMinimumElementsAttribute(int minelements)
    {
        _minelements = minelements;
    }

    public override bool IsValid(object value)
    {
        var list = value as IList;
        if (list != null)
        {
            return list.Count >= _minelements;
        }
        return false;
    }
}

然后：

[EnsureMinimumElements(1,ErrorMessage = "At least a person is required")]
public List<Person> Persons { get; private set; }
Personally I use FluentValidation.NET instead of Data Annotations to perform validation because I prefer the imperative validation logic instead of the declarative. I think it is more powerful. So my validation rule would simply look like this:

RuleFor(x => x.Persons)
    .Must(x => x.Count > 0)
    .WithMessage("At least a person is required");