Overriding JsonConverter Json.Net

Question

I have been working on an app using the Amazon affiliate API. I use a C# library (Nager.AmazonProductAdvertising) to make calls to the affiliate API but I am stuck.

The library doesn't include making variation matrix response group call to amazon affiliate API, so I had to use web request object to make the call. After making the call, the API returns an XML response, which I serialize to JSON. And then deserialize to a class.

The issue I am having is that sometimes the returned JSON can be have array or an object on variation attribute. I need help in writing a custom converter class to accept either an array or object on the same property.

Here are the two different sample JSON response.

{
 "?xml": {
"@version": "1.0"
},
 "ItemLookupResponse":
{
"@xmlns": "http://webservices.amazon.com/AWSECommerceService/2013-08-01",
"OperationRequest":
  {
  "RequestId": "d141ff28-2ef1-44a1-b2ce-97972f09ffcf",
  "Arguments": {
    "Argument": [
      {
        "@Name": "AWSAccessKeyId",
        "@Value": "accessid"
      },
      {
        "@Name": "AssociateTag",
        "@Value": "mytag"
      },
      {
        "@Name": "Condition",
        "@Value": "All"
      },
      {
        "@Name": "ItemId",
        "@Value": "B01KIOU4EO"
      },
      {
        "@Name": "Operation",
        "@Value": "ItemLookup"
      },
      {
        "@Name": "ResponseGroup",
        "@Value": "VariationMatrix"
      },
      {
        "@Name": "Timestamp",
        "@Value": "2018-03-29T06:46:40Z"
      },
      {
        "@Name": "Version",
        "@Value": "2013-08-01"
      },
      {
        "@Name": "http://webservices.amazon.com/onca/xml?Service",
        "@Value": "AWSECommerceService"
      },
      {
        "@Name": "Signature",
        "@Value": "jhsjvhjvjsbjsonksljkksjb="
      },
      {
        "@Name": "Service",
        "@Value": "AWSECommerceService"
      }
    ]
  },
  "RequestProcessingTime": "0.0053435950000000"
},
"Items": {
  "Request": {
    "IsValid": "True",
    "ItemLookupRequest": {
      "Condition": "All",
      "IdType": "ASIN",
      "ItemId": "B01KIOU4EO",
      "ResponseGroup": "VariationMatrix",
      "VariationPage": "All"
    }
  },
  "Item": {
    "ASIN": "B01KIOU4EO",
    "ParentASIN": "B01KIOU4EO",
    "Variations": {
      "TotalVariations": "6",
      "TotalVariationPages": "1",
      "VariationDimensions": {
        "VariationDimension": [
          "Color",
          "Configuration"
        ]
      },
      "Item": [
        {
          "ASIN": "B01J24C0TI",
          "ItemAttributes": {
            "Color": "Black"
          },
          "VariationAttributes": {
            "VariationAttribute": [
              {
                "Name": "Configuration",
                "Value": "Echo Show"
              },
              {
                "Name": "Color",
                "Value": "Black"
              }
            ]
          }
        },
        {
          "ASIN": "B076C9DLGS",
          "ItemAttributes": {
            "Color": "Black"
          },
          "VariationAttributes": {
            "VariationAttribute": [
              {
                "Name": "Configuration",
                "Value": "Echo Show  + Amazon Cloud Cam"
              },
              {
                "Name": "Color",
                "Value": "Black"
              }
            ]
          }
        },
        {
          "ASIN": "B0767ZHCZG",
          "ItemAttributes": {
            "Color": "Black"
          },
          "VariationAttributes": {
            "VariationAttribute": [
              {
                "Name": "Configuration",
                "Value": "Show + Kasa Security Camera"
              },
              {
                "Name": "Color",
                "Value": "Black"
              }
            ]
          }
        },
        {
          "ASIN": "B010CEHQTG",
          "ItemAttributes": {
            "Color": "White"
          },
          "VariationAttributes": {
            "VariationAttribute": [
              {
                "Name": "Configuration",
                "Value": "Echo Show"
              },
              {
                "Name": "Color",
                "Value": "White"
              }
            ]
          }
        },
        {
          "ASIN": "B076C52ZPC",
          "ItemAttributes": {
            "Color": "White"
          },
          "VariationAttributes": {
            "VariationAttribute": [
              {
                "Name": "Configuration",
                "Value": "Echo Show  + Amazon Cloud Cam"
              },
              {
                "Name": "Color",
                "Value": "White"
              }
            ]
          }
        },
        {
          "ASIN": "B0767ZQZ3F",
          "ItemAttributes": {
            "Color": "White"
          },
          "VariationAttributes": {
            "VariationAttribute": [
              {
                "Name": "Configuration",
                "Value": "Show + Kasa Security Camera"
              },
              {
                "Name": "Color",
                "Value": "White"
               }
             ]
           }
         }
       ]
     }
   }
 }
 }
}

Second response:

 {
"?xml": {"@version": "1.0"
 },

 "ItemLookupResponse": {

"@xmlns": "http://webservices.amazon.com/AWSECommerceService/2013-08-01",
"OperationRequest": {
  "RequestId": "207d197c-b29c-446f-a976-7dc9e37c5feb",
  "Arguments": {
    "Argument": [
      {
        "@Name": "AWSAccessKeyId",
        "@Value": "accessid"
      },
      {
        "@Name": "AssociateTag",
        "@Value": "mytag"
      },
      {
        "@Name": "Condition",
        "@Value": "All"
      },
      {
        "@Name": "ItemId",
        "@Value": "B06X9FX834"
      },
      {
        "@Name": "Operation",
        "@Value": "ItemLookup"
      },
      {
        "@Name": "ResponseGroup",
        "@Value": "VariationMatrix"
      },
      {
        "@Name": "Timestamp",
        "@Value": "2018-03-29T06:35:22Z"
      },
      {
        "@Name": "Version",
        "@Value": "2013-08-01"
      },
      {
        "@Name": "http://webservices.amazon.com/onca/xml?Service",
        "@Value": "AWSECommerceService"
      },
      {
        "@Name": "Signature",
        "@Value": "kkkbkjkjsbjbisvuhjshshuvhs"
      },
      {
        "@Name": "Service",
        "@Value": "AWSECommerceService"
      }
    ]
  },
  "RequestProcessingTime": "0.0105003370000000"
},

"Items": {
  "Request": {
    "IsValid": "True",
    "ItemLookupRequest": {
      "Condition": "All",
      "IdType": "ASIN",
      "ItemId": "B06X9FX834",
      "ResponseGroup": "VariationMatrix",
      "VariationPage": "All"
    }
  },
  "Item": {
    "ASIN": "B06X9FX834",
    "ParentASIN": "B06X9FX834",
    "Variations": {
      "TotalVariations": "4",
      "TotalVariationPages": "1",
      "VariationDimensions": {
        "VariationDimension": "Color"
      },
      "Item": [
        {
          "ASIN": "B01MZFKJL2",
          "ItemAttributes": {
            "Color": "black"
          },
          "VariationAttributes": {
            "VariationAttribute": {
              "Name": "Color",
              "Value": "black"
            }
          }
        },
        {
          "ASIN": "B01MUG5WIN",
          "ItemAttributes": {
            "Color": "blue"
          },
          "VariationAttributes": {
            "VariationAttribute": {
              "Name": "Color",
              "Value": "blue"
            }
          }
        },
        {
          "ASIN": "B01N5V0FVK",
          "ItemAttributes": {
            "Color": "grey"
          },
          "VariationAttributes": {
            "VariationAttribute": {
              "Name": "Color",
              "Value": "grey"
            }
          }
        },
        {
          "ASIN": "B01N284QCU",
          "ItemAttributes": {
            "Color": "red"
          },
          "VariationAttributes": {
            "VariationAttribute": {
              "Name": "Color",
              "Value": "red"
            }
          }
        }
      ]
    }
   }
  }
 }
}

this is the the class it is being deserialized to

 using System;
 using System.Collections.Generic;
 using System.Net;

 using System.Globalization;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Converters;
 using Newtonsoft.Json.Linq;
 using System.Reflection;

 namespace try
{
[JsonObject(MemberSerialization = MemberSerialization.OptIn)]
public class RootObject
{
    [JsonProperty("?xml")]
    public Xml Xml { get; set; }
    [JsonProperty("ItemLookupResponse")]
    public ItemLookupResponse ItemLookupResponse { get; set; }
}
public class Xml
{
    [JsonProperty("@version")]
    public string Version { get; set; }
}
public class ItemLookupResponse
{
    [JsonProperty("@xmlns")]
    public string Xmlns { get; set; }
    [JsonProperty("OperationRequest")]
    public OperationRequest OperationRequest { get; set; }
    [JsonProperty("Items")]
    public Items Items { get; set; }
}
public class OperationRequest
{
    [JsonProperty("RequestId")]
    public string RequestId { get; set; }
    [JsonProperty("Arguments")]
    public Arguments Arguments { get; set; }
    [JsonProperty("RequestProcessingTime")]
    public string RequestProcessingTime { get; set; }
}
public class Arguments
{
    [JsonProperty("Argument")]
    public List<Argument> Argument { get; set; }
}
public class Argument
{
    [JsonProperty("@Name")]
    public string Name { get; set; }
    [JsonProperty("@Value")]
    public string Value { get; set; }
}
public class Items
{
    [JsonProperty("Request")]
    public Request Request { get; set; }
    [JsonProperty("Item")]
    public Item Item { get; set; }
}
public class Request
{
    [JsonProperty("IsValid")]
    public string IsValid { get; set; }
    [JsonProperty("ItemLookupRequest")]
    public ItemLookupRequest ItemLookupRequest { get; set; }
}
public class ItemLookupRequest
{
    [JsonProperty("Condition")]
    public string Condition { get; set; }
    [JsonProperty("IdType")]
    public string IdType { get; set; }
    [JsonProperty("ItemId")]
    public string ItemId { get; set; }
    [JsonProperty("ResponseGroup")]
    public string ResponseGroup { get; set; }
    [JsonProperty("VariationPage")]
    public string VariationPage { get; set; }
}
public class Item
{
    [JsonProperty("ASIN")]
    public string ASIN { get; set; }
    [JsonProperty("ParentASIN")]
    public string ParentASIN { get; set; }
    [JsonProperty("Variations")]
    public Variations Variations { get; set; }
}
public class Variations
{
    [JsonProperty("TotalVariations")]
    public string TotalVariations { get; set; }
    [JsonProperty("TotalVariationPages")]
    public string TotalVariationPages { get; set; }
    [JsonProperty("VariationDimensions")]
    public VariationDimensions VariationDimensions { get; set; }
    [JsonProperty("Item")]
    public List<Item1> Item { get; set; }
}
public class VariationDimensions
{
    [JsonProperty("VariationDimension")]
    [JsonConverter(typeof(SingleOrArrayConverter<string>))]
    public List<string> VariationDimension { get; set; }
}
public class Item1
{
    [JsonProperty("ASIN")]
    public string ASIN { get; set; }
    [JsonProperty("ItemAttributes")]
    public ItemAttributes ItemAttributes { get; set; }
    [JsonProperty("VariationAttributes")]
    public VariationAttributes VariationAttributes { get; set; }
}

public class ItemAttributes
{
    [JsonProperty("Size")]
    public string Size { get; set; }
}
public class VariationAttributes
{
   [JsonConverter(typeof(SingleOrArrayConverter<string>))]

    [JsonProperty("VariationAttribute")]
    public List<VariationAttribute> VariationAttribute { get; set; }
}

public class VariationAttribute
{
    [JsonProperty("Name")]
    public string Name { get; set; }
    [JsonProperty("Value")]
    public string Value { get; set; }
  }
}

class SingleOrArrayConverter<T> : JsonConverter

{
public override bool CanConvert(Type objectType)
{
    return (objectType == typeof(List<T>));
}

public override object ReadJson(JsonReader reader, Type objectType, object existingValue,JsonSerializer serializer)
{
    JToken token = JToken.Load(reader);
    if (token.Type == JTokenType.Array)
    {
        return token.ToObject<List<T>>();
    }
    return new List<T> { token.ToObject<T>() };
}

public override bool CanWrite
{
    get { return false; }
}

  public override void WriteJson(JsonWriter writer,_
     objectvalue,JsonSerializer serializer)
{
    throw new NotImplementedException();
 }
}

https://www.jerriepelser.com/blog/custom-converters-in-json-net-case-study-1/ This link may help you. I think you need custom json deserializer — Adem Catamak, Mar 29 '18 at 08:23
Sounds like you want [How to handle both a single item and an array for the same property using JSON.net](https://stackoverflow.com/q/18994685/3744182). — dbc, Mar 29 '18 at 09:02
Actually it looks like you're already using `SingleOrArrayConverter` from that answer. So, what is your problem? Which property is not working? If an exception is thrown, what is the full `ToString()` output of the exception including the exception type, message, traceback and inner exception? — dbc, Mar 29 '18 at 09:05
{"Cannot deserialize the current JSON object (e.g. {\"name\":\"value\"}) into type 'System.Collections.Generic.List`1[Liksis.VariationAttribute]' because the type requires a JSON array (e.g. [1,2,3]) to deserialize correctly.\r\nTo fix this error either change the JSON to a JSON array — Stanley Ekpunobi, Mar 29 '18 at 13:06
(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) 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.\r\nPath 'ItemLookupResponse.Items.Item.Variations.Item[0].VariationAttributes.VariationAttribute.Name', line 1, position 1320."} — Stanley Ekpunobi, Mar 29 '18 at 13:06
@dbc yes I am already using the answer from the link. The property that is giving the error is variationattributes. This is the error message above, I had to split it to get post the full error message. — Stanley Ekpunobi, Mar 29 '18 at 13:10
it looks like you don't need the VariantionAttributes-class. In class Item1 you only need a List, not an additional container class for that list. Right now, you have your class VariationAttributes that contains a list named VariationAttribute that in turn contains items named VariationAttribute. — Dirk Trilsbeek, Mar 29 '18 at 13:16

Overriding JsonConverter Json.Net

0 Answers0