Deserializing a JSON string to a C# class where JSON class may accept either array / object based on a JSON property

Question

I have to deserialize a JSON string to C# classes inorder to bind to a grid. I have implemented the respective classes in C#. But at a particular instance, this fails because the JSON property will be either an array or an object. Please check a part of the string.

I have created ItemList class with 3 properties IL1 , Name and another object class "Item". However, you can see that when the property "Name" is Rubber, I should have List of Item class as a property rather than Item object. When it is Rubber, it returns array of 2 items.

 "ItemList": [
{
  "@IL1": "Yes",
  "@Name": "Pencil"
  "Item": {
    "@ItemType": "Pencil",
    "@Item2": "1A7716744F7048ACA2549BE93F0A2BF1",        
    "aimLink": {
      "@id": "1A7716744F7048ACA2549BE93F0A2BF1",
      "@DisplayText": "P00001"         
    }
  }
},
{
  "@IL1": "Yes",
  "@Name": "Pen",    
  "Item": {
    "@ItemType": "Pen",
    "@Item2": "AE067F7EDB6147C09AED243C1F7FAD25",        
    "aimLink": {
      "@id": "AE067F7EDB6147C09AED243C1F7FAD25",
      "@DisplayText": "5100010654120001
    }
  }
},
{
  "@IL1": "Yes",
  "@Name": "Rubber",     
  "Item": [
    {
      "@ItemType": "Rubber",
      "@ItemGID": "622025629037499394DF092DA16BAB7F",          
      "aimLink": {
        "@id": "622025629037499394DF092DA16BAB7F",
        "@DisplayText": "12345678-1234-123456-7116#01"
      }
    },
    {
      "@ItemType": "Rubber",
      "@ItemGID": "F336F65F8E014E80B84A2312F829493C"
      "aimLink": {
        "@id": "F336F65F8E014E80B84A2312F829493C",
        "@DisplayText": "12345678-1234-123456-7116#14"
      }
    }
  ]
}
 ],

How can I parse this to a C# class effectively and the easiest way to get this done?

Thanks, Divya

The best thing to do is to fix the JSON so that it is unambiguous. — Mark Benningfield
– Mark Benningfield, Commented Mar 18, 2021 at 14:16
if its the same object coming single or collection then its possible, you can check if jobject then deserialize to object otherwise to list or array — Ehsan Sajjad
– Ehsan Sajjad, Commented Mar 18, 2021 at 14:32
What serializer are you using? Newtonsoft.Json (a.k.a. Json.Net)? — Brian Rogers
– Brian Rogers, Commented Mar 18, 2021 at 20:17

Anas Sabbah · Accepted Answer · 2021-03-18 15:15:21Z

2

You can resolve this issue by making your custom JsonConverter and you can use below to convert single value to array then mark Item property with the JsonConverter attribute

public class SingleValueArrayConverter<T> : JsonConverter
{
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }



    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        object retVal = new Object();
        if (reader.TokenType == JsonToken.StartObject)
        {
            T instance = (T)serializer.Deserialize(reader, typeof(T));
            retVal = new List<T>() { instance };
        }
        else if (reader.TokenType == JsonToken.StartArray)
        {
            retVal = serializer.Deserialize(reader, objectType);
        }
        return retVal;
    }

    public override bool CanConvert(Type objectType)
    {
        return false;
    }
}

let's assume this your ItemList class

public class ItemList
{
    public string @IL1 { get; set; }
    public string @Name { get; set; }
    [JsonConverter(typeof(SingleValueArrayConverter<Item>))]
    public List<Item> Item { get; set; }
}

public class Item
{
    public string @ItemType { get; set; }
    public string @Item2 { get; set; }
    public AimLink aimLink { get; set; }
}

public class AimLink
{
    public string @id { get; set; }
    public string @DisplayText { get; set; }
}

answered Mar 18, 2021 at 15:15

Anas Sabbah

213 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

user3323130 Over a year ago

Thank you Anas. That worked. I have 1 more clarification. I am deserializing using this code - JObject studentObj = JObject.Parse(jsonString); var res = JsonConvert.DeserializeObject<Archive>(jsonString); If my json string looks like this , how can I extract the Archive part only {"?xml":{"@version":"1.0","@encoding":"UTF-8"}, "?xml-stylesheet":"type=\"text/xsl\" href=\"./xslt/Archive.xslt\"", "Archive":{"@DateTimeCreated":"2021-03-08T18:17:31",.....................

Anas Sabbah Over a year ago

make archive inside another class like that then var res = JsonConvert.DeserializeObject<Rootobject>(jsonString);

public class Rootobject     {         public Archive Archive { get; set; }     }      public class Archive     {         public DateTime DateTimeCreated { get; set; }     }

Andrey · Accepted Answer · 2021-03-18 15:01:27Z

0

You can make your custom JsonConverter (e.g. ItemConverter) and mark Item property with the [JsonConverter(typeof(ItemConverter))] attribute

answered Mar 18, 2021 at 15:01

Andrey

1731 silver badge11 bronze badges

Collectives™ on Stack Overflow

Deserializing a JSON string to a C# class where JSON class may accept either array / object based on a JSON property

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related