asp.net-mvc-3 - 在 ASP.NET MVC3 中，如何手动对生成的属性应用验证

Question

情况是这样的，我在数据库中定义了大约 20 个属性(称为属性)的列表。这包括一个名称、可能的值、一个可选的正则表达式、一个指示该字段是必需的 bool 值等。

在我的 ViewModel 中，我得到了属性列表，在我的 List View 中，我有一个很好的 AttributeViewModel EditorTemplate，可以使用 Steve Sanderson 的酷 BeginCollectionItem 来显示它们。确保帖子被绑定(bind)回 AttributeViewModel 列表(这工作得很好)。

我的 AttributeViewModel 看起来像这样:

public class AttributeViewModel
{
    public string Description { get; set; }
    public IEnumerable<SelectListItem> Values { get; set; }
    public string SelectedValue { get; set; }
    public byte RenderAs { get; set; }
    public int AttributeID { get; set; }
    public int ID { get; set; }
    public int RegexValidation { get; set; }
    public bool IsRequired { get; set; }
}

我的 View 看起来像这样 (edit.cshtml):

@model Company.Services.ViewModels.StaffMemberViewModel

<h2>Edit</h2>
@using (Html.BeginForm())
{
    Some fields here, nothing of interest.

    @Html.EditorFor(model => model.AttributeValues)

    <input type="submit" value="Send" />
 }

不过，这是有趣的一点，这是我的 AttributeValues 编辑器模板:

@using Company.Web.Helpers // This is where "BeginCollectionItem" lives
@model Company.Services.ViewModels.AttributeViewModel

using (Html.BeginCollectionItem("attributes"))
{
    <div class="editor-label">
        @Model.Description
    </div>
    <div class="editor-field">
       @Html.DropDownListFor(m => m.SelectedValue, new SelectList(Model.Values, "Value", "Text"), "-- Select --")
       @Html.HiddenFor(model => model.AttributeID) 
    </div>
}

我想做的是使用 IsRequired 和 RegexValidation 来确保每个属性的 SelectedValue 有效。我将如何去做呢？如果可能的话，我真的很想像我“通常”那样利用 MVC3 验证框架和不显眼的验证。

我显然不能动态添加 RequiredAttribute 或 RegularExpressionAttribute，因为列表中的每个属性对象都不同。

Answer 1

这是未经测试的。您可能需要尝试一下才能获得想要的结果。

首先，创建您的自定义 DataAnnotationsModelValidatorProvider 类:

public class MyModelMetadataValidatorProvider : DataAnnotationsModelValidatorProvider
{
    internal static DataAnnotationsModelValidationFactory DefaultAttributeFactory = Create;
    internal static Dictionary<Type, DataAnnotationsModelValidationFactory> AttributeFactories = 
        new Dictionary<Type, DataAnnotationsModelValidationFactory>() 
        {
            {
                typeof(RequiredAttribute),
               (metadata, context, attribute) => new RequiredAttributeAdapter(metadata, context, (RequiredAttribute)attribute)
            },
            {
                typeof(RegularExpressionAttribute),
               (metadata, context, attribute) => new RegularExpressionAttributeAdapter(metadata, context, (RegularExpressionAttribute)attribute)
            }
        };

    internal static ModelValidator Create(ModelMetadata metadata, ControllerContext context, ValidationAttribute attribute)     
    {
        return new DataAnnotationsModelValidator(metadata, context, attribute);
    }

    protected override IEnumerable<ModelValidator> GetValidators(ModelMetadata metadata, ControllerContext context, IEnumerable<Attribute> attributes)
    {
        List<ModelValidator> vals = base.GetValidators(metadata, context, attributes).ToList(); 
        if (metadata.ModelType.Name == "SelectedValue")
        {
            // get our parent model
            var parentMetaData = ModelMetadataProviders.Current.GetMetadataForProperties(context.Controller.ViewData.Model, 
                metadata.ContainerType);

            // get the associated AttributeId
            var attributeId = Convert.ToInt32(parentMetaData.FirstOrDefault(p => p.PropertyName == "AttributeId").Model);

            // get AttributeViewModel with specified AttributeId from repository
            var attributeViewModel = _db.AttributeViewModels.FirstOrDefault(x => x.AttributeId == attributeId);

            DataAnnotationsModelValidationFactory factory;

            // check if required
            if (attributeViewModel.IsRequired)
            {
                // must be marked as required
                var required = new RequiredAttribute();
                required.ErrorMessage = attributeViewModel.Description.Trim() +
                    " is Required";
                if (!AttributeFactories.TryGetValue(required.GetType(), out factory))
                    factory = DefaultAttributeFactory;

                vals.Add(factory(metadata, context, required));
            }

            // check for regex
            if (attributeViewModel.RegexValidation > 0)
            {
                // get regex from repository
                var regexValidation = _db.attributeViewModels.
                    FirstOrDefault(x => x.RegexValidation == attributeViewModel.RegexValidation);
                var regex = new RegularExpressionAttribute(regexValidation.Pattern);
                regex.ErrorMessage = attributeViewModel.Description.Trim() +
                    " is not in a valid format";
                if (!AttributeFactories.TryGetValue(regex.GetType(), out factory))
                    factory = DefaultAttributeFactory;

                vals.Add(factory(metadata, context, regex));
            }
        }
        return vals.AsEnumerable();
    }
}

然后，将以下内容添加到 Global.asax.cs 中的 Application_Start:

ModelValidatorProviders.Providers.Clear();
ModelValidatorProviders.Providers.Add(new MyModelMetadataValidatorProvider());