I am trying to deserialize a Unix timestamp to a DateTime. In my case, I need to do much more checks before I can set a property to DateTime from a timestamp. If I use DateTime from Newtonsoft.Json it deserializes it to UTC time and I need to deserialize it to a specific timezone
The problem is that I am not able to get the correct time. It seems like my string to long parsing is failing. If I can get the long unix timestamp, I can get the rest of the logic working
I have a class named Alert
class Alert
{
// Some properties
[JsonConverter(typeof(UnixTimestampJsonConverter))]
public DateTime Created { get; set; }
// Some more properties
}
the class UnixTimestampJsonConverter is
class UnixTimestampJsonConverter : JsonConverter
{
// Other override methods
public override object ReadJson (JsonReader reader, Type objectType,
object existingValue, JsonSerializer serializer)
{
if (reader.TokenType == JsonToken.EndObject)
return null;
if (reader.TokenType == JsonToken.StartObject) {
long instance = serializer.Deserialize<long> (reader);
return TimeUtils.GetCustomDateTime (instance);
}
return null;
}
}
Where TimeUtils.GetCustomDateTime (instance) takes the long unixtimestamp and converts it into DateTime object of specific timezone.
I am in a PCL library with Profile 78, so I have limited access to System.TimeZoneInfo and I am using PCL version of NodaTime for other timezone calculations.
In case anyone is interested, this is the project on Github - MBTA Sharp
I'm pretty sure all you need to do is call serializer.Deserialize. Doing this will advance the reader correctly and you shouldn't need to do anything else:
public class UnixTimestampJsonConverter : JsonConverter
{
public override object ReadJson(
JsonReader reader,
Type objectType,
object existingValue,
JsonSerializer serializer)
{
long ts = serializer.Deserialize<long>(reader);
return TimeUtils.GetMbtaDateTime(ts);
}
public override bool CanConvert(Type type)
{
return typeof(DateTime).IsAssignableFrom(type);
}
public override void WriteJson(
JsonWriter writer,
object value,
JsonSerializer serializer)
{
throw new NotImplementedException();
}
public override bool CanRead
{
get { return true; }
}
}
Example: https://dotnetfiddle.net/Fa8Zis
Related
I have a asp.net core web API project in that when I am returning a JSON result to the UI all the decimal values is converting to whole number, when I debug the controller I can see that two decimal point .00 but when I check it in the console network tab it is coming as whole number.
So, how can I add a formatter that will keep the decimal value as it is that is coming from the DB, it should not convert it to a whole number by the time it reaches the UI.
When I debug the controller -
In the console network tab-
You could custom serializer for the decimal property
public class TestModel
{
[JsonConverter(typeof(DecimalConverter))]
public decimal Price { get; set; }
}
public class DecimalConverter : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return (objectType == typeof(decimal));
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
writer.WriteValue(((decimal)value).ToString("0.00"));
}
public override bool CanRead
{
get { return false; }
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
throw new NotImplementedException();
}
}
Result:
I am trying to deserialize the following JSON (which validates on https://jsonlint.com/):
{"pandoc-api-version":[1,22],"meta":{"title":{"t":"MetaBlocks","c":[{"t":"Para","c":[{"t":"Str","c":"Dynamic"},{"t":"Space"},{"t":"Str","c":"Language"},{"t":"Space"},{"t":"Str","c":"Runtime"}]},{"t":"Para","c":[]}]}},"blocks":[{"t":"Para","c":[{"t":"Strong","c":[{"t":"Str","c":"Bill"},{"t":"Space"},{"t":"Str","c":"Chiles"},{"t":"Space"},{"t":"Str","c":"and"},{"t":"Space"},{"t":"Str","c":"Alex"},{"t":"Space"},{"t":"Str","c":"Turner"}]}]},{"t":"Para","c":[{"t":"Emph","c":[{"t":"Strong","c":[{"t":"Str","c":"Reading"},{"t":"Space"},{"t":"Str","c":"this"},{"t":"Space"},{"t":"Str","c":"Document:"}]}]}]}]}
into the following classes:
internal record TagContent(string T, OneOf<TagContent[], string>? C);
internal class RawPandoc {
[JsonProperty] public int[] PandocApiVersion = default!;
[JsonProperty] public Dictionary<string, TagContent> Meta = default!;
[JsonProperty] public TagContent[] Blocks = default!;
}
using the following code:
var settings = new JsonSerializerSettings {
ContractResolver = new DefaultContractResolver { NamingStrategy = new KebabCaseNamingStrategy() },
Converters = new JsonConverter[] { new OneOfJsonConverter() }
};
var pandoc = JsonConvert.DeserializeObject<RawPandoc>(s, settings);
and I get the following error:
Unexpected token when deserializing object: StartObject. Path 'meta.title.c[0]', line 1, position 69.
How can I resolve this?
For completeness, here is the current and incomplete code for OneOfJsonConverter. OneOf is a library for union types in C#:
using OneOf;
namespace PandocFilters {
public class OneOfJsonConverter : JsonConverter {
public override void WriteJson(JsonWriter writer, object? value, JsonSerializer serializer) {
if (value is IOneOf of) {
value = of.Value;
}
serializer.Serialize(writer, value);
}
public override object? ReadJson(JsonReader reader, Type objectType, object? existingValue, JsonSerializer serializer) {
if (reader.Value is null) { return null; }
// TODO not implemented yet
return reader.Value;
}
public override bool CanConvert(Type objectType) => objectType.UnderlyingIfNullable().GetInterfaces().Contains(typeof(IOneOf));
}
}
Problem is you are not advancing the reader in your ReadJson implementation. You declared your converter can handle IOneOf objects, and so JSON.NET expects your converter to actually read and handle it, however it does nothing as of now. So ReadJson is called (at the start of first array in json which should be deserialized to OneOf), and then after it returns - reader position is still where it was before (at start of array), which is not what JSON.NET expects. Then it fails trying to continue reading next object, because its assumptions are violated. So, just implement ReadJson, and meanwhile you can advance a reader for example like that:
public override object? ReadJson(JsonReader reader, Type objectType, object? existingValue, JsonSerializer serializer) {
// advance reader as expected
var eitherStringOrArray = JObject.ReadFrom(reader);
return reader.Value;
}
We have upgraded Newtonsoft.Json from 10.0.3 to 11.0.1 and code that has been working previously does not work anymore.
We have following JSON:
[{"mail-type":"registration","response":"250 OK id=1UjnNr-gdf-C0 ","invoice-id":,"email":"testuser08#test.com"}]
and we call following method:
var events = JsonConvert.DeserializeObject<Event[]>(jsonEvents);
This worked fine on 10.0.3, but does not on 11.0.1. On this version following exception is thrown:
Exception thrown: 'Newtonsoft.Json.JsonReaderException' in
Newtonsoft.Json.dll
Additional information: An undefined token is not a valid
System.Nullable`1[System.Int64]. Path '[0].invoice-id', line 1.
I tried to pass following options to DeserializeObject
var settings = new JsonSerializerSettings
{
NullValueHandling = NullValueHandling.Ignore,
MissingMemberHandling = MissingMemberHandling.Ignore
};
But still the same error. What changes have to be done to make it work on 11.0.1. I am affraid we cannot accomodate JSON output as this comes from third party API.
Your JSON sample is not well-formed. If I upload your JSON to https://jsonlint.com/ then the following error is generated:
Error: Parse error on line 4:
...0 ", "invoice-id": , "email": "testuse
----------------------^
Expecting 'STRING', 'NUMBER', 'NULL', 'TRUE', 'FALSE', '{', '[', got ','
The line in question is as follows:
"invoice-id": ,
According to the JSON standard there needs to be a value between the : and the ,. But, why did this work in Json.NET 10.0? Apparently it was a bug, which was fixed. According to the 11.0.1 release notes:
Fix - Fixed not erroring when reading undefined for nullable long
So if we assume that your Event type looks like this:
public partial class Event
{
[JsonProperty("invoice-id")]
public long? InvoiceId { get; set; }
// Other properties as required
}
Then in 10.0 your JSON could be deserialized successfully using this type, but in 11.0 it cannot. If, however, we change InvoiceId to be an int?:
public partial class Event
{
[JsonProperty("invoice-id")]
public int? InvoiceId { get; set; }
// Other properties as required
}
It fails in both versions. Thus the fix appears to have been to handle int? and long? consistently.
Ideally, you should ask whoever sent you such JSON to fix it so that it is well-formed as defined by http://www.json.org/ and RFC 8259. If you nevertheless need to parse such JSON in the same manner as Json.NET 10.0, you could introduce TolerantNullableLongConverter as follows:
public class TolerantNullableLongConverter : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return objectType == typeof(long?);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
if (reader.TokenType == JsonToken.Null)
return null;
if (reader.TokenType == JsonToken.Undefined)
return null;
if (reader.Value is long)
return reader.Value;
// string or int or decimal or ...
return serializer.Deserialize<long>(reader);
}
public override bool CanWrite { get { return false; } }
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
throw new NotImplementedException();
}
}
And apply it to your type as follows:
public partial class Event
{
[JsonProperty("invoice-id")]
[JsonConverter(typeof(TolerantNullableLongConverter))]
public long? InvoiceId { get; set; }
// Other properties as required
}
You can implement workaround with custom converter:
internal class NullableLongFixupConverter : JsonConverter {
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer) {
writer.WriteValue(value);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer) {
// if token undefined - return null
if (reader.TokenType == JsonToken.Undefined)
return null;
// otherwise - value
return (long?) reader.Value;
}
public override bool CanConvert(Type objectType) {
return objectType == typeof(long?);
}
}
Then you can either decorate properties with it:
class Event {
[JsonProperty("invoice-id")]
[JsonConverter(typeof(NullableLongFixupConverter))]
public long? InvoiceId { get; set; }
}
or register globally (will be invoked only for properties of type long?):
JsonConvert.DefaultSettings = () =>
{
var s = new JsonSerializerSettings();
s.Converters.Add(new NullableLongFixupConverter());
return s;
};
In my ASP.NET web service I need all my dates to be serialized to JSON as numbers which represent a number of milliseconds passed since 1970 please. I'm using Newtonsoft.Json serializer. What do I need to do to set it up this way?
UPDATE:
the available documentation (http://www.newtonsoft.com/json/help/html/DatesInJSON.htm) only mentions serializing a single object with custom settings, what i am looking for is the default serialization settings that would govern serialization of any object
Off the top of my head I would get the ticks of the 1970 date subtract it from the ticks of the current date then divide by 10000 since there are 10000 ticks in a milisecond. This will give you a number which should be easier to serialize. You could make this an extension method of DateTime. Ticks on MSDN:
DateTime.Ticks
Have a look at this excellent blog post on creating your own DateTime converter to deal with your requirement. Example actually shows you creating UnixDateTimeConverter.
I'm not sure if this is the easiest way, but you can create a custom converter for DateTimes, then a custom JsonMediaTypeFormatter which uses that converter.
// This class overrides conversion for DateTime values
public class MyDateConverter : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return objectType == typeof(DateTime);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
throw new NotImplementedException();
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
// Your algorithm here
var customValue = ((DateTime)value).Ticks;
writer.WriteValue(customValue);
}
}
// This formatter will create serializers with the above converter injected
public class MyJsonFormatter : JsonMediaTypeFormatter
{
public override JsonSerializer CreateJsonSerializer()
{
var serializer = base.CreateJsonSerializer();
serializer.Converters.Add(new MyDateConverter());
return serializer;
}
}
// Inside your WebApi config code, replace the default formatter with your custom one
var defaultJsonFormatter = config.Formatters.OfType<JsonMediaTypeFormatter>().First();
config.Formatters.Remove(defaultJsonFormatter);
config.Formatters.Insert(0, new MyJsonFormatter());
here is what worked:
public class MyConverter: JsonConverter
{
public override bool CanConvert(Type type)
{
return (type == typeof(DateTime) || type == typeof(DateTime?));
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
return new NotSupportedException("An attempt to read a date using a write-only converter from DateTime -> number of milliseconds since 1970.");
}
static readonly long ticksTo1970 = new DateTime(1970, 1, 1).Ticks;
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
if (value is DateTime)
{
var date = (DateTime)value;
var unixDateSpan = new TimeSpan(date.Ticks - ticksTo1970);
var milliseconds = (long)unixDateSpan.TotalMilliseconds;
writer.WriteValue(milliseconds);
}
else
{
throw new NotSupportedException("A value of unexpected type where a DateTime value is expected.");
}
}
}
public class BaseApiController : ApiController
{
[NonAction]
protected JsonResult<T> MyJson<T>(T data)
{
var result = this.Json(data);
result.SerializerSettings.Converters.Insert(0, new MyConverter());
return result;
}
}
I'm using the official Mongo C# Driver, and RestSharp to call a Rest Api with Json.NET to perform my serialization/deserialization. Say I have a Person class as follows, which I'd like to POST & GET:
public class Person
{
[JsonProperty("_id"),JsonConverter(typeof(ObjectIdConverter))]
public ObjectId Id {get;set;}
public string Name {get;set;}
}
I create a new Person object:
var person = new Person{Id = ObjectId.GenerateId(),Name='Joe Bloggs'};
POST it, and on the server I see the following which is correct:
{ _id: 52498b56904ee108c99fbe88, name: 'Joe Bloggs'}
The problem, is when I perform a GET the ObjectId I get on the client is {0000000000000...}
i.e. not the {5249.....} I'd expect. The raw response is showing the correct value, but once I deserialize I loose it.
The ObjectIdConverter code is :
public class ObjectIdConverter : JsonConverter
{
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
serializer.Serialize(writer, value.ToString());
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
var objectId = (ObjectId)existingValue; // at this point existingValue is {000...}
return objectId;
}
public override bool CanConvert(Type objectType)
{
return (objectType == typeof (ObjectId));
}
}
Any help would be appreciated.
You are implementing the ReadJson method of the converter incorrectly. The existingValue parameter does not give you the deserialized value read from the JSON, it gives you the existing value of the object that you will be replacing. In most cases this will be null or empty. What you need to do is use the reader to get the value from the JSON, convert it as needed, then return the converted value.
Assuming your ObjectId class has a constructor that accepts a hex string, here is how you would implement the ReadJson method:
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
JToken token = JToken.Load(reader);
return new ObjectId(token.ToObject<string>());
}