c# - 如何在 C# 中使用 Json.NET 从 JSON 访问嵌套对象

Question

如何使用类修饰在嵌套对象中选择 json 值 "estimatedLocationDate"？属性“estimatedLocationDate”始终返回 null 而不是值 2015-10-01T14:00:00.000。其他装饰值返回正确的值。

这是我的C#类

public string id { get; set; }

public string name { get; set; }

[JsonProperty("publishedDate")]
public string publishdate { get; set; }

[JsonProperty("estimatedLocationDate")]
public string estimatedLocationDate{ get; set; }

[JsonProperty("createdTime")]
public string createtime { get; set; }

[JsonProperty("lastUpdatedTime")]
public string lastupdate { get; set; }

这是 JSON

"planet": [
    {
        "id": "123456",
        "planetid": "en-us/Jupiter-mars/---main",
        "name": "The planet Mercury",
        "description": "This is placeholder for the description",
        "publishedDate": "2013-10-14T23:30:00.000",
        "createtime": "2012-03-01T14:00:00.000",
        "product": {
            "moreid": "1427-48-bd-9-113",
            "color": "200",
            "imageUrl": "http://image.bing.com/Mercury.jpg",
            "neighbor": [
                {
                    "ring": "Two",
                    "moons": 2
                }
            ],
            "estimatedLocationDate": "2014-10-01T14:00:00.000"
        },

Answer 1

您发布的 JSON 无效。您可以在 JsonLint 验证您的 JSON。

假设下面是您的 JSON 数据。

{ "planet": [
        {
            "id": "123456",
            "planetid": "en-us/Jupiter-mars/---main",
            "name": "The planet Mercury",
            "description": "This is placeholder for the description",
            "publishedDate": "2013-10-14T23:30:00.000",
            "createtime": "2012-03-01T14:00:00.000",
            "product": {
                "moreid": "1427-48-bd-9-113",
                "color": "200",
                "imageUrl": "http://image.bing.com/Mercury.jpg",
                "neighbor": [
                    {
                        "ring": "Two",
                        "moons": 2
                    }
                ],
                "estimatedLocationDate": "2014-10-01T14:00:00.000"
            }
        }
    ]
}

阅读整个 JSON 的简单方法是将其反序列化 到适当的类层次结构。如果您还没有，您可以按照以下步骤在 Visual Studio 中创建

• Copy your JSON data
• Create a new empty class in VS
• VS > Edit > Paste Special > Paste JSON As Classes

这是生成的类

public class PlanetRoot
{
    public Planet[] planet { get; set; }
}

public class Planet
{
    public string id { get; set; }
    public string planetid { get; set; }
    public string name { get; set; }
    public string description { get; set; }
    public Product product { get; set; }
    [JsonProperty("publishedDate")]
    public string publishdate { get; set; }
    [JsonProperty("createdTime")]
    public string createtime { get; set; }
}

public class Product
{
    public string moreid { get; set; }
    public string color { get; set; }
    public string imageUrl { get; set; }
    public Neighbor[] neighbor { get; set; }
    public DateTime estimatedLocationDate { get; set; }
}

public class Neighbor
{
    public string ring { get; set; }
    public int moons { get; set; }
}

现在，很容易读取整个对象并像这样访问您的 estimatedLocationDate

var jsonString = File.ReadAllText(@"C:\YourDirectory\YourFile.json");

PlanetRoot planet = JsonConvert.DeserializeObject<PlanetRoot>(jsonString);
DateTime estimatedLocationDate = planet.planet.First().product.estimatedLocationDate;

或者，如果您不想读取整个对象，您可以像这样使用 Json.NET Linq-to-JSON 直接读取该属性

var jObject = JObject.Parse(jsonString);
var estLocDate = jObject["planet"][0]["product"]["estimatedLocationDate"].ToObject<DateTime>();