Question

模型绑定工作正常，直到我在以下类之上实现接口：

public class QuestionAnswer : IQuestionAnswer
    {

        public Int32 Row_ID { get; set; }
        public Int32 Column_ID { get; set; }
        public String Value { get; set; }

    }

    public class HiddenAnswer : IHiddenAnswer
    {

        public Int32 Hidden_Field_ID { get; set; }
        public String Hidden_Field_Value { get; set; }

    }

    public class SurveyAnswer : ISurveyAnswer
    {

        public string SessionID { get; set; }

        public List<IQuestionAnswer> QuestionAnswerList { get; set; }

        public List<IHiddenAnswer> HiddenAnswerList { get; set; }

        public SurveyAnswer()
        {
            QuestionAnswerList = new List<IQuestionAnswer>();
            HiddenAnswerList = new List<IHiddenAnswer>();
        }
    }

现在接口就在那里，我得到一个500 (Internal Server Error)

我用来建模绑定的javascript如下：

$('#submitbutton').click(function () {

            var answers = new Array();
            var hiddenfields = new Array();

            var formname = "#" + $("#formname").val();

            $(':input', formname).each(function () {

                if ($(this).is(":text") || $(this).is(":radio") || $(this).is(":checkbox")) 
                {
                    var answerObject = {
                        Column_ID: $(this).attr('data-column_id'),
                        Row_ID: $(this).attr('data-row_id'),
                        Value: $(this).attr('data-theValue')
                    };

                    answers.push(answerObject);
                }

                else if($(this).is(":hidden")) {
                    var hiddenObject = 
                    {
                        Hidden_Field_ID: $(this).attr('data-hidden_field_id'),
                        Hidden_Field_Value: $(this).attr('data-hidden_field_value')
                    }

                    hiddenfields.push(hiddenObject);
                }
            });

            $('textarea', formname).each(function () {
                var answerObject = {
                    Column_ID: $(this).attr('data-column_id'),
                    Row_ID: $(this).attr('data-row_id'),
                    Value: $(this).val(),
                };

                answers.push(answerObject);
            });

            var allAnswers = {
                SessionID: 0,
                QuestionAnswerList: answers,
                HiddenAnswerList: hiddenfields
            }

            postForm(allAnswers);
        });

Controller Action如下所示：

 [AcceptVerbs(HttpVerbs.Post)]
        public ActionResult SubmitSurvey(SurveyAnswer answers)
        {
            // Dette tillader CORS
            Response.AppendHeader("Access-Control-Allow-Origin", "*");

            bc.SaveSurvey(answers);

            return null;
        }

我做错了什么？

Answer 1

我做错了什么？

您不能指望模型绑定器知道当它遇到IQuestionAnswer视图模型上的SurveyAnswer界面时，它应该使用QuestionAnswer类型。很高兴您已经声明了接口的这种实现，但模型绑定器对它没有任何线索。

因此，您必须为IQuestionAnswer接口编写自定义模型绑定器（对于IHiddenAnswer接口相同）并指出您希望使用哪个实现：

public class QuestionAnswerModelBinder : DefaultModelBinder
{
    protected override object CreateModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Type modelType)
    {
        var type = typeof(QuestionAnswer);
        var model = Activator.CreateInstance(type);
        bindingContext.ModelMetadata = ModelMetadataProviders.Current.GetMetadataForType(() => model, type);
        return model;
    }
}

将在您的Application_Start注册：

ModelBinders.Binders.Add(typeof(IQuestionAnswer), new QuestionAnswerModelBinder());

如何建模绑定实现接口的类？

1 个答案: