列表的 ViewModel 验证

问题描述

我有以下视图模型定义

public class AccessRequestViewModel
{
    public Request Request { get; private set; }
    public SelectList Buildings { get; private set; }
    public List<Person> Persons { get; private set; }
}

因此，在我的应用程序中，必须至少有 1 人才能提出访问请求.您可以使用什么方法来验证?我不希望这种验证发生在我的控制器中，这很容易做到.唯一的选择是自定义验证属性吗?

So in my application there must be at least 1 person for an access request. What approach might you use to validate? I don't want this validation to happen in my controller which would be simple to do. Is the only choice a custom validation attribute?

目前正在使用 FluentValidation(不错的库！)执行此验证

Currently performing this validation with FluentValidation (nice library!)

RuleFor(vm => vm.Persons)
                .Must((vm, person) => person.Count > 0)
                .WithMessage("At least one person is required");

推荐答案

如果您使用数据注释来执行验证，您可能需要一个自定义属性:

If you are using Data Annotations to perform validation you might need a custom attribute:

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; }

或者使其更通用:

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; }

我个人使用 FluentValidation.NET 而不是 Data Annotations 来执行验证，因为我更喜欢命令式验证逻辑的声明.我认为它更强大.所以我的验证规则看起来就像这样:

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");

这篇关于列表的 ViewModel 验证的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！