Deserialize nested json with when key values are unknown object

Question

I have a 5 objects nested json file. In nutshell, the json file has the following pattern:

 {
    "Object1": {
        "Object2": {
            "Object3": {
                "Object4": [
                    "Object5",
                    "Object5",
                    "Object5"
                ]
            }
        }
    }
}

Edit: Previously I had inconsistent naming. I have revised the names to reflect the comments that I was given.

I would like to deserialize the json into a C# object as follows

using System;
using Newtonsoft.Json;
namespace Example
{
    class Program
    {
        public class Object1
        {

            public string Name { get; set; }
            public Object2[] Object2s { get; set; }
        }
        public sealed class Object2
        {
            public string Name { get; set; }
            public Object3[] Object3s { get; set; }

        }
        public class Object3
        {
            public string Name { get; set; }
            public Object4 [] Object4s { get; set; }
        }
        public class Object4
        {
            public string Name { get; set; }
            public Object5 [] Object5s { get; set; }
        }
        public class Object5
        {
            public string Name { get; set; }
        }

        static void Main(string[] args)
        {
            string json = "{    \"Object1\": {    \"Object2\": {      \"Object3\": {        \"Object4\": [          \"Value1\",\"Value2\",\"Value3\"        ]    }  }}}";


            Object1[] object1s = JsonConvert.DeserializeObject<Object1[]>(json);

            Console.WriteLine(object1s[0].Name);
            

        }
    }
}

Unfortunately, when I run it, it results in the following exception:

 Newtonsoft.Json.JsonSerializationException
  HResult=0x80131500
  Message=Cannot deserialize the current JSON object (e.g. {"name":"value"}) into type 'Example.Program+Object1[]' because the type requires a JSON array (e.g. [1,2,3]) to deserialize correctly.
To fix this error either change the JSON to a JSON array (e.g. [1,2,3]) or change the deserialized type so that it is a normal .NET type (e.g. not a primitive type like integer, not a collection type like an array or List<T>) that can be deserialized from a JSON object. JsonObjectAttribute can also be added to the type to force it to deserialize from a JSON object.
Path 'Object1', line 1, position 15.

Is there any way this can be achieved without resorting to looping through the json tree?

Object4 is repeated twice in your json... that is illegal. Something that was said in your previous post you deleted. — Jawad, Jan 24 '21 at 18:47
@Jawad thanks a lot! I just revised the code and removed the offending object — Batz-Castelmore d'Artagnan, Jan 24 '21 at 18:56
For multiple keys, not strictly illegal, but generally only the last key is used. See [here](https://stackoverflow.com/questions/20714160/how-to-deserialize-json-with-duplicate-property-names-in-the-same-object/20721137) for workarounds — Charlieface, Jan 24 '21 at 20:24

Martin Staufcik · Answer 1 · 2021-01-24T19:17:14.840

The exception is thrown, because you are trying to deserialize an json object into an array. This will not work

Object1[] object1s = JsonConvert.DeserializeObject<Object1[]>(json);

This will work:

Object1 object1 = JsonConvert.DeserializeObject<Object1>(json);

You will also need to change either the json or the class model, because again the current json contains objects and the class model expects arrays. This code is the updated class model to fit the json file:

    public class Object1
    {
        public string Name { get; set; }
        public Object2 Object2 { get; set; }
    }
    public sealed class Object2
    {
        public string Name { get; set; }
        public Object3 Object3 { get; set; }

    }
    public class Object3
    {
        public string Name { get; set; }
        public string[] Object4 { get; set; } 
    }

One more issue is in the JSON, there are two properties of the same name inside a json object:

    "Object4": [
      "Object5",
      "Object5",
      "Object5"
    ],
    "Object4": [
      "Object5",
      "Object5",
      "Object5"
    ]

If you want to have multiple objects Object4 inside Object3, you could use an array:

{
    "Object1": {
        "Object2": {
            "Object3": {
                "Object4": [{
                        "Object5": [{}, {}, {}
                        ]
                    }, {
                        "Object5": [{}, {}, {}
                        ]
                    }
                ],
            }
        }
    }
}

@Jawad thanks for catching the error! The suggested solution results in a null value instead of the object. — Batz-Castelmore d'Artagnan, Jan 24 '21 at 19:09

Deserialize nested json with when key values are unknown object

1 Answers1