从ModelMetaData获取另一个属性的值

Question

我试图从GetClientValidationRules自定义验证属性的方法中获取另一个属性的值.

这是我的尝试(基于达林对另一个问题的回答):

public IEnumerable<ModelClientValidationRule> GetClientValidationRules(
    ModelMetadata metadata, ControllerContext context)
{
    var parentType = metadata.ContainerType;
    var parentMetaData = ModelMetadataProviders.Current
        .GetMetadataForType(null, parentType);

    var parentMetaData = ModelMetadataProviders.Current
        .GetMetadataForProperties(context.Controller.ViewData.Model, parentType); 

    var otherProperty = parentMetaData.FirstOrDefault(p => 
        p.PropertyName == "SomeProperty");

    var otherValue = otherProperty.Model;

    var rule = new ModelClientValidationRule
    {
        ValidationType = "customvalidatorattribute",
        ErrorMessage = this.FormatErrorMessage(metadata.GetDisplayName()),
    };

    yield return rule;
}

但是,在尝试设置时otherValue,我得到:

System.Reflection.TargetException:Object与目标类型不匹配.

Answer 1

问题是你没有传入绑定模型.更改以下两行:

var parentMetaData = ModelMetadataProviders.Current
    .GetMetadataForProperties(context.Controller.ViewData.Model, parentType); 
var otherValue = (string)parentMetaData.FirstOrDefault(p => 
    p.PropertyName == "SomeProperty").Model;

这将获得当前模型的完整元数据(包括绑定值).