使用JSONPath或SelectTokens查询JSON？在C＃中使用JSON.NET

Question

我正在尝试在C＃中使用Newtonsoft.Json.Net。以下是我需要从中检索数据的JSON文件的一部分：

{
    "video":{
        "local_recording_device":{
            "codecs":null
        },
        "preferred_string":"___PREFERRED___",
        "streams":{
            "99176901":{
                "id":"99176901",
                "name":"PTZ Camera",
                "site":"someone",
                "email":"someone@awebsite.com",
                "codec":"VP8 HD1 (720p)",
                "local":true,
                "screen":false,
                "fit_to_window":true,
                "stay_on_top":false,
                "layout":0,
                "native_width":1280,
                "native_height":720,
                "window_width":456,
                "window_height":254,
                "preferred":false,
                "local_recording":false,
                "device_id":"MJPEG Camera",
                "normalized_device_id":"MJPEGCamera",
                "shared_window_id":"MJPEG Camera",
                "enable":true,
                "big_location":"2",
                "x":347,
                "y":737,
                "window_id":"197302",
                "camera_id":null
            },
            "3091494011":{
                "id":"3091494011",
                "name":"Logitech Webcam C930e",
                "site":"Joe Smith",
                "email":"joe@awebsite.com",
                "codec":"VP8 Medium (CIF)",
                "local":false,
                "screen":false,
                "fit_to_window":true,
                "stay_on_top":false,
                "layout":0,
                "native_width":352,
                "native_height":288,
                "window_width":864,
                "window_height":702,
                "preferred":true,
                "local_recording":false,
                "enable":true,
                "big_location":"1",
                "x":204,
                "y":0,
                "window_id":"197296",
                "camera_id":null
            },
            "3798287599":{
                "id":"3798287599",
                "name":"Drive Camera",
                "site":"ASiteName",
                "email":"asitesame@awebsite.com",
                "codec":"VP8 HD1 (720p)",
                "local":true,
                "screen":false,
                "fit_to_window":true,
                "stay_on_top":false,
                "layout":0,
                "native_width":1280,
                "native_height":720,
                "window_width":456,
                "window_height":254,
                "preferred":true,
                "local_recording":false,
                "device_id":"Logitech Webcam C930e",
                "normalized_device_id":"LogitechWebcamC930e",
                "shared_window_id":"Logitech Webcam C930e",
                "enable":true,
                "big_location":"3",
                "x":814,
                "y":737,
                "window_id":"262822",
                "camera_id":null
            }
        }
    }
}

因此，在JSON数据内部是：流中的“视频”，“流”可以是x个不同的流（流ID）。“流”（长号）中的流可以随时更改。在我的示例中，这里有三个。我需要搜索“信息流”中的所有信息流，并查看其中是否有匹配特定电子邮件地址的“电子邮件”。每个流都有一个“电子邮件”。如果电子邮件与我提供的电子邮件地址匹配，我需要检查流“启用”以查看它是真还是假。

感谢您为我提供正确的指导。我以前没有使用过JSON数据。

Answer 1

您可以使用LINQ转JSON并SelectTokens执行所需的查询：

        string json = GetJson();
        var obj = JObject.Parse(json);
        var testEmail = "someone@awebsite.com";

        var streamQuery = obj.SelectTokens("video.streams.*").Where(s => (string)s["email"] == testEmail);
        var firstEnabled = streamQuery.Select(s => (bool?)s["enable"]).FirstOrDefault();

该查询返回null的bool是true或者false如果所需的电子邮件第一流被启用，或者null如果该电子邮件地址不流。

请注意，这将返回与给定电子邮件地址匹配的第一个流的enabled状态。如果您想知道是否启用了任何功能，请执行以下操作：

        var anyEnabled = streamQuery.Any(s => (bool)s["enable"]);