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c# - 如何将此 json 转换为字符串并获取“id”属性的值

问题描述

我想只返回 jsonList 中的课程 ID。但我的代码不起作用。

我的json输出：

"{\"courses\":[{\"id\":5,\"fullname\":\"Course temp\",\"displayname\":\"Course temp\",\"shortname\":\"ct\",\"categoryid\":17,\"categoryname\":\"Course templates\",\"sortorder\":40002,\"summary\":\"\",\"summaryformat\":1,\"summaryfiles\":[],\"overviewfiles\":[],\"contacts\":[],\"enrollmentmethods\":[\"manual\"],\"idnumber\":\"\",\"format\":\"topics\",\"showgrades\":1,\"newsitems\":5,\"startdate\":20120160,\"enddate\":20120160,\"maxbytes\":0,\"showreports\":0,\"visible\":1,\"groupmode\":0,\"groupmodeforce\":0,\"defaultgroupingid\":0,\"enablecompletion\":1,\"completionnotify\":0,\"lang\":\"\",\"theme\":\"\",\"marker\":0,\"legacyfiles\":0,\"calendartype\":\"\",\"timecreated\":1583825606,\"timemodified\":1583910617,\"requested\":0,\"cacherev\":1583913808,\"filters\":[{\"filter\":\"displayh5p\",\"localstate\":0,\"inheritedstate\":1},{\"filter\":\"mathjaxloader\",\"localstate\":0,\"inheritedstate\":1},{\"filter\":\"activitynames\",\"localstate\":0,\"inheritedstate\":1},{\"filter\":\"mediaplugin\",\"localstate\":0,\"inheritedstate\":1}],\"courseformatoptions\":[{\"name\":\"hiddensections\",\"value\":0},{\"name\":\"coursedisplay\",\"value\":0}]}],\"warnings\":[]}"

我的代码：（我只想返回id）

public int GetCourseDetails(Course course)
{
    string URI = "http://localhost/Moodle/webservice/rest/server.php";
    using (WebClient wc = new WebClient())
    {
        wc.QueryString.Add("wstoken", "49345fa96c58118326b874bxxxxx");
        wc.QueryString.Add("wsfunction", "core_course_get_courses_by_field");
        wc.QueryString.Add("moodlewsrestformat", "json");
        wc.QueryString.Add("field", "shortname");
        wc.QueryString.Add("value",course.shortname);


        var response_data = wc.UploadValues(URI, "POST", wc.QueryString);

        var response = Encoding.ASCII.GetString(response_data);
       // return response;
        var k = JsonConvert.DeserializeObject<List<dynamic>>(response);

        foreach (var a in k)
        {
            id = (a["id"]);
        }
        return id;

    }
}

标签： c#jsonmoodle-api

解决方案

由于您的根对象不是数组，因此您需要将 Json 反序列化为dynamic而不是List<dynamic>，然后通过此动态对象选择第一门课程并获得id如下：

var k = JsonConvert.DeserializeObject<dynamic>(response);

var courseList = k.courses;
id = Convert.ToInt32(courseList[0]["id"]);

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