Problem with DeserializeObject Json String

Question

I get the following json string format from an API:

{
 "Items":[
 {
 "Item":{
 "Codes":{},
 "Date":1523539700000,
 "Name":"Item1",
 "Price":"15"
 }
 },
 {
 "Item":{
 "Codes":{
 "productcode":"a",
 "departmentcode":"b",
 "storecode":"c"
 },
 "Date":1523537700000,
 "Name":"Item2",
 "Price":"20"
 }
 },
 {
 "Item":{
 "Codes":{
 "productcode":"a",
 "departmentcode":"b",
 "storecode":"c"
 },
 "date":1523539700000,
 "name":"Item3",
 "price":"30"
 }
 }
 ]
}

I am not interested in the Codes element and then created the following class:

public class Item
 {
 [JsonConverter(typeof(ConvertItemDateTime))]
 [JsonProperty(PropertyName = "dateReceived")]
 public DateTime DateReceived { get; set; }
 [JsonProperty(PropertyName = "name")]
 public string Name{ get; set; }
 [JsonProperty(PropertyName = "price")]
 public double Price{ get; set; }
 public IList<Items> itemListResults { get; set; } //For view
 public int productid; // Added for view
 }

I then try an parse it...

JObject jsondata = JObject.Parse(responseToString(response))
var values = json.GetValue("Items");

...which by this point I can see that variable 'values' still contains each value (Date, Name, Price) inside each item. Then I try and deserialize it...

IList<Items> itemList = new List<Items>();
itemList = JsonConvert.DeserializeObject<IList<Items>>(values.ToString());

When I debug from this point onward I can see a list with the exact number of items I am expecting but all the values (Date, Name, Price) are null. The Date value inside the json will change (from the API side). Sometimes it will be a long and sometimes a string date format containing a "[GMT]".

My ConvertItemDateTime method is as follow:

public class ConvertItemDateTime : JsonConverter
 {
 private static readonly DateTime UnixEpoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
 public override bool CanConvert(Type objectType)
 {
 Console.WriteLine(objectType);
 return true;
 }
 public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
 {
 Console.WriteLine(value.GetType());
 long ticks;
 if (value is DateTime)
 {
 var dateTime = (DateTime)value;
 ticks = (long)(dateTime.ToUniversalTime() - UnixEpoch).TotalMilliseconds;
 }
 else if (value is DateTimeOffset)
 {
 var dateTimeOffset = (DateTimeOffset)value;
 ticks = (long)(dateTimeOffset.ToUniversalTime() - UnixEpoch).TotalMilliseconds;
 }
 else
 {
 throw new JsonSerializationException("Expected date object value.");
 }
 if (ticks < 0)
 {
 throw new JsonSerializationException("Cannot convert date value that is before Unix epoch of 00:00:00 UTC on 1 January 1970.");
 }
 writer.WriteValue(ticks);
 }
 public override bool CanRead
 {
 get { return true; }
 }
 public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
 {
 long ticks;
 if (reader.TokenType == JsonToken.Integer)
 {
 ticks = (long)reader.Value;
 }
 else if (reader.TokenType == JsonToken.String)
 {
 var stringValue = reader.Value.ToString();
 if (stringValue.Contains("[GMT]"))
 {
 stringValue = stringValue.Substring(0, stringValue.Length - 6);
 DateTime createdDate = DateTime.Parse(stringValue);
 return createdDate;
 }
 if (!long.TryParse((string)reader.Value, out ticks))
 {
 throw new JsonSerializationException("Cannot convert invalid value.");
 }
 }
 else
 {
 throw new JsonSerializationException("Unexpected token parsing date.");
 }
 if (ticks >= 0)
 {
 DateTime d = UnixEpoch.AddMilliseconds(ticks);
 Type t = objectType;
 if (t == typeof(DateTimeOffset))
 {
 return new DateTimeOffset(d, TimeSpan.Zero);
 }
 return d;
 }
 else
 {
 throw new JsonSerializationException("Cannot convert value that is before Unix epoch of 00:00:00 UTC on 1 January 1970.");
 }
 }
 }
}

Please help me to get this working.

• Jonathan Alfaro: In my opinion if the date field changes format you should just make it a string in your model and later on when you are going to use it then convert it. Also your model does not match property DateReveived.

Answer 1

You can't simply deserialise to an IList, you need an object that has an Items property. For example:

public class RootObject
{
 public IList<Item> Items { get; set; }
}

The other issue I can see is that the JsonProperty for your DateReceived property needs to match the JSON name which is just date.

Answer 2

Here is a full working sample:

this is my model:

 public class RootObject
 {
 public List<ItemContainer> Items { get; set; }
 }
 public class ItemContainer
 {
 public Item Item { get; set; }
 }
 public class Item
 {
 public Codes Codes { get; set; }
 public string Date { get; set; }
 public string Name { get; set; }
 public string Price { get; set; }
 }
 public class Codes
 {
 public string Productcode { get; set; }
 public string Departmentcode { get; set; }
 public string Storecode { get; set; }
 }

This is how I deserialize it:

var result = JsonConvert.DeserializeObject<RootObject>(json);//json is a string that contains the json input.

I have noticed several problems with your example:

1. DataReceived is a property that does not exist in the json model.
2. Your Json is inconsistent. Name, Date and Price are also found in lowercase: date, name and price. Your json should be consistent.
3. You are trying to do too much in one spot. You should just take the input of date as a string and later on convert it to one or several useful formats or types. Keep your deserialization/serialization simple and save yourself headaches.