asp.net循环遍历json数据错误答案

【问题标题】：asp.net looping through json data errorasp.net循环遍历json数据错误
【发布时间】：2014-08-01 22:05:05
【问题描述】：

我用的是这个例子：

http://weblog.west-wind.com/posts/2012/Aug/30/Using-JSONNET-for-dynamic-JSON-parsing

测试一些动态 JSON 循环，但我收到一个错误，即我的数据属性之一不存在，即使我在数据中看到它。这是我的 JSON 数据：

[
{
    "$id": "1",
    "$type": "TheAPI.Models.Category, TheAPI",
    "Id": 1,
    "Name": "Marina Park",
    "Description": "Morbi elementum diam sit amet mi viverra.",
    "IsActive": true,
    "NewsCategories": [
        {
            "$id": "2",
            "$type": "TheAPI.Models.NewsCategory, TheAPI",
            "Id": 1,
            "NewsId": 2,
            "CategoryId": 1,
            "News": {
                "$id": "3",
                "$type": "TheAPI.Models.News, TheAPI",
                "Id": 2,
                "Headline": "Fake News Heading 2",
                "ShortDesc": "A short description about the news item 2.",
                "Body": "Mortgage loan rates may change daily. To ensure that you receive the rate you were quoted, you may elect to lock in your rate by paying an up-front authorization fee",
                "CreateDate": "2014-07-04T00:00:00.000",
                "PublishDate": "2014-07-04T00:00:00.000",
                "ExpireDate": "2014-12-31T00:00:00.000",
                "NewsCategories": [
                    {
                        "$ref": "2"
                    }
                ]
            },
            "Category": {
                "$ref": "1"
            }
        },
        {
            "$id": "4",
            "$type": "TheAPI.Models.NewsCategory, TheAPI",
            "Id": 5,
            "NewsId": 4,
            "CategoryId": 1,
            "News": {
                "$id": "5",
                "$type": "TheAPI.Models.News, TheAPI",
                "Id": 4,
                "Headline": "Fake News Heading 4",
                "ShortDesc": "A short description about the news item 4.",
                "Body": "Mortgage loan rates may change daily. To ensure that you receive the rate you were quoted, you may elect to lock in your rate by paying an up-front authorization fee",
                "CreateDate": "2014-07-04T00:00:00.000",
                "PublishDate": "2014-07-04T00:00:00.000",
                "ExpireDate": "2014-12-31T00:00:00.000",
                "NewsCategories": [
                    {
                        "$ref": "4"
                    }
                ]
            },
            "Category": {
                "$ref": "1"
            }
        }
    ]
}

]

这是我使用它的 .Net 代码：

    private void LoadNews()
    {
        //var url = apiurl + "/news";
        var url = apiurl + "/categories?$filter=Id eq 1&$expand=NewsCategories/News";


        var syncClient = new WebClient();
        var content = syncClient.DownloadString(url);

        //Response.Write(content);

        JArray jsonVal = JArray.Parse(content) as JArray;
        dynamic categories = jsonVal;

        foreach (dynamic category in categories)
        {
            Response.Write("Cat Name: " + category.Name + "<br>");
            foreach (dynamic newscat in category.NewsCategories)
            {
                foreach (dynamic news in newscat.News)
                {
                    Response.Write(news.Headline + "<br>");
                }
            }
        }

        //ListView1.DataSource = categories.News;
        //ListView1.DataBind();

    }

当我运行上述程序时，似乎我的每个新闻都没有像 newscat 和类别那样的所有数据属性。我收到以下错误：

System.Core.dll 中出现“Microsoft.CSharp.RuntimeBinder.RuntimeBinderException”类型的异常，但未在用户代码中处理

附加信息：“Newtonsoft.Json.Linq.JProperty”不包含“标题”的定义

任何帮助将不胜感激。非常感谢。

【问题讨论】：

标签： asp.net json dynamic foreach

【解决方案1】：

NewsCategory 上的 News 属性不是一个数组（只是一个对象）。下面的 .c# 代码可能比这解释得更好......

foreach (dynamic category in categories)
{
    Response.Write("Cat Name: " + category.Name + "<br>");
    foreach (dynamic newscat in category.NewsCategories)
    {
            Response.Write(newscat.News.Headline + "<br>");
    }
}

【讨论】：