CODEWITHSUNDEEP
c#jsonjson.net
山杰 孟
山杰 孟

Reputation: 39

How to judge the node of json exists

I am using Newtonsoft.Json to Deserialize json string to Object, but I can't judge if the node is null or not. eg. jo["data"]["prevtime"], sometimes json has the node of ["prevtime"], sometimes doesn't have ["prevtime"]. If ["prevtime"] is null, it will report an error.

var jo = JObject.Parse(content);
if (jo["data"].ToString() == "")
    return new StatusCollection();

var jInfo = jo["data"]["info"];
StatusCollection list = new StatusCollection();
Status status = null;

if (jInfo != null)
{
    foreach (var j in jInfo.Children())
    {

       if (jo["data"]["prevtime"] != null) 
       {
           status.Nexttime = jo["data"]["nexttime"].ToString();
           status.Prevtime = jo["data"]["prevtime"].ToString();
       }

       status = j.ToObject<Status>();
       if (!string.IsNullOrEmpty(status.Head))
       {
           status.Head += "/50";
       }
       if (!string.IsNullOrEmpty(status.From))
       {
           status.From = "来自" + status.From;
       }
       list.Add(status);
    }
}

Upvotes: 2

Views: 4061

Answers (2)

m.rufca
m.rufca

Reputation: 2688

Try to select the token you want, and there is a property to get the token value

if (jo["data"].Select("prevtime") != null) 
{
        status.Prevtime = jo["data"].Value<string>("prevtime");
        status.Nexttime = jo["data"].Value<string>("nexttime");
}

JSON.NET Documentation:

Link 1

Link 2

Upvotes: 2

Mayank Taneja
Mayank Taneja

Reputation: 31

In the current version, it would be like :

if (jo["data"].Select***Token***("prevtime") != null) 
{
        status.Prevtime = jo["data"].Value<string>("prevtime");
        status.Nexttime = jo["data"].Value<string>("nexttime");
}

Upvotes: 3

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