Json Constructor with null parameters

Question

After trying to solve it myself and looking for answers on stackoverflow. I need to ask you guys if you can help me.

I dont really know where ir my error, but the fact is that the class I am using to deserialize a json is not being constructed correctly. I get all parameters null.

my class is :

public class Page
{
    public int rolePermission;

    public string icon;

    public string title;

    public string url;

    [JsonProperty(NullValueHandling = NullValueHandling.Ignore)]
    public Page[] children;

    [JsonConstructor]
    public Page(string rolePermission, string icon, string title, string url, Page[] children)
    {
        this.rolePermission = int.Parse(rolePermission);
        this.icon = icon;
        this.title = title;
        this.url = url;
        this.children = children;
    }
}

The json is:

{
   "page":
   {
      "rolePermission":"2",
      "icon":"dashboard",
      "title":"Dashboard",
      "url":"Dashboard"
   }
}

The children property could be or not on the json and I think there is the problem.

The json with children would be:

 {
       "page":
       {
          "rolePermission":"2",
          "icon":"dashboard",
          "title":"Dashboard",
          "url":"Dashboard",
          "children": 
           {
             "page":{
               "rolePermission":"2",
               "icon":"dashboard",
               "title":"Dashboard",
               "url":"Dashboard"
              }
           }
       }
}

I wish you can help me guys :)

I would expect children to be an array in the JSON rather than just an object - and I wouldn't expect a page name, either. — Jon Skeet
– Jon Skeet, Commented Mar 9, 2020 at 13:08
@JonSkeet Thank you for the comment Jon. And, do you know why (on the first json without children) is the cosntructor null ? — Mr.Deer
– Mr.Deer, Commented Mar 9, 2020 at 13:12
I don't know what you mean by "is the constructor null". (I don't understand the title of the question either.) — Jon Skeet
– Jon Skeet, Commented Mar 9, 2020 at 13:43

Kit · Accepted Answer · 2020-03-09 13:31:01Z

2

Your JSON is off by one level. You have an extra {} around your root object page, which should be unnamed. Try this:

{
   "rolePermission":"2",
   "icon":"dashboard",
   "title":"Dashboard",
   "url":"Dashboard"
}

Or try this with, as Jon says, an array for children:

   {
     "rolePermission":"2",
     "icon":"dashboard",
     "title":"Dashboard",
     "url":"Dashboard",
     "children": 
     [
       {
         "rolePermission":"2",
         "icon":"dashboard",
         "title":"Dashboard",
         "url":"Dashboard"
       }
     ]
   }

answered Mar 9, 2020 at 13:31

Kit

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1 Comment

Mr.Deer Over a year ago

Hi Kit, I tested it and it works :) Thank you very much for the answer. In agregation I would say that on the Json.Convert we can remove the root item if like in my case we can not change the json structure.

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