如何获取JSON中的数组并循环遍历它以获取其元素

Question

在C#中，我制作了一个GET reqeust来获取一些JSON数据。在这个JSON数据中有一个数组，我想返回这个数据中的元素。我正在使用Json.NET来尝试实现这一点。

以下是我在JSON文件中获取属性的C#代码。

public static string sendRequest(string url, string method) 
{
    try
    {
        // Set reqiued information for api
        var httpWebRequest = (HttpWebRequest)WebRequest.Create(main_url + url);
        httpWebRequest.ContentType = "application/x-www-form-urlencoded";
        httpWebRequest.Headers.Add("Authorization", "Bearer " + Current_Access_Token);
        httpWebRequest.Accept = "application/json;v=1";
        httpWebRequest.Method = method;
        // Get adn return responses
        var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
        string respStr = new StreamReader(httpResponse.GetResponseStream()).ReadToEnd();
        return respStr;
    }
    catch (Exception e)
    {
        MessageBox.Show("No response");
    }
    return "";
}
public static string GetUserName()
{
    string resp = sendRequest("api.php/currentCustomer/", "GET");
    JObject jObject = JObject.Parse(resp);
    JToken Juser = jObject["response"];
    string UserName = (string)Juser["data"]["customer"]["name"];
    return UserName;
}

上面的代码是我如何在customer下返回客户的名称。但在customer下面有一个数组"active_digital_subscriptions"。在这个数组中，有两个元素我想访问并保存在setting.setting中。"active_digital_subscriptions"只包含字符串。

JSON数据：

{  
   "response":{  
      "code":200,
      "status":"success",
      "data":{  
         "customer":{  
            "id":"109701",
            "email":"[e-mail]",
            "name":"ahjune152",
            "first_name":"Loc",
            "last_name":"Dai Le",
            "registration_date":"2015-06-17",
            "last_login_date":"2015-11-05",
            "is_newsletter_subscriber":"1",
            "digital_password":"YOtI1cuzL18dO3i9T9CBVCiX3lQa3iIPhcWDgiwHxxI=",
            "language":{  
               "id":"1",
               "name":"American english",
               "code":"en"
            },
            "currency":{  
               "id":"1",
               "name":"Danske kroner",
               "sign":"DKK",
               "code":"DKK",
               "number":"208"
            },
            "preferred_platforms":[  
            ],
            "active_digital_subscriptions":[  
               {  
                  "plan_id":"246",
                  "plan_title":"VIP Partner"
               }
            ]
         }
      }
   }
}

Answer 1

您可以将SelectToken和SelectTokens用于此目的。两者都支持JSONPath查询语法：

var userName = (string)Juser.SelectToken("data.customer.name");
var customersItems = Juser.SelectTokens("data.customer.customers_items[*]")
    .Select(t => (string)t)
    .ToArray();

[*]是一个通配符，用于选择数组中的所有元素。

更新

考虑到您修改后的JSON，您可以获得活动用户和活动订阅，如下所示：

var userName = (string)Juser.SelectToken("data.customer.name");
var activeSubscriptions = Juser.SelectTokens("data.customer.active_digital_subscriptions[*]")
    .Select(t => new { PlanId = (string)t["plan_id"], PlanTitle = (string)t["plan_title"] })
    .ToArray();

请注意，活动订阅在一个数组中，因此可能存在多个订阅。如果你知道只有一个，你可以做

var activeSubscription = activeSubscriptions.SingleOrDefault();

在这里，我以匿名类型返回订阅，但如果您愿意，可以定义一个显式类：

public class Subscription
{
    public string PlanId { get; set; }
    public string PlanTitle { get; set; }
}

然后做：

var activeSubscriptions = Juser.SelectTokens("data.customer.active_digital_subscriptions[*]")
    .Select(t => new Subscription { PlanId = (string)t["plan_id"], PlanTitle = (string)t["plan_title"] })
    .ToArray();

Answer 2

你可以试试这个-

var subs = (JArray)JObject.Parse(json)["response"]["data"]["customer"]["active_digital_subscriptions"];
for (var i = 0; i < subs.Count; ++i)
{
     var id = ((JValue)subs[i]["plan_id"]).Value;
     var title = ((JValue)subs[i]["plan_title"]).Value;
}