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How to discard JSON elements with specific values while deserializing

This is an interesting situation. My application saves and loads JSON data from MongoDB, which works fine 95% of the time. The JSON data in such cases is like the following:
{
"isDemo": true,
"CustomerReference": "nabTest",
"Fee": null,
"OrderId": "48/XYZ3",
"Asynchronous": false,
}
The remaining 5% of the time,a legacy application loads some XML data, converts that into JSON format and inserts that into the same MongoDB collection. The JSON data in such cases is like this:
{
"#xmlns:xsi":"http://www.w3.org/2001/XMLSchema-instance",
"#xmlns:xsd":"http://www.w3.org/2001/XMLSchema",
"#xmlns":"http://MyDomain.com.au/SomeService.Contract/2007/06/18",
"isDemo":{
"#xmlns":"http://MyDomain.com.au/ABC.Services",
"#text":"true"
},
"Asynchronous":{
"#xmlns":"http://MyDomain.com.au/ABC.Services"
"#text":"false"
},
"Fee":{
"#xsi:nil":"true",
"#xmlns":"http://MyDomain.com.au/ABC.Services"
},
"CustomerReference":{
"#xmlns":"http://MyDomain.com.au/ABC.Services"
},
"OrderId":"48/XYZ3"
}
In such cases, Newtonsoft deserializer crashes with the following exception:
Newtonsoft.Json.JsonReaderException: 'Unexpected character encountered
while parsing value: {. Path 'CustomerReference', line 1, position
919.'
The minimum code for this is the following:
// 'result' is of type object, loaded from MongoDB
var resultStr = JsonConvert.SerializeObject(result);
var obj = JsonConvert.DeserializeObject<T>(resultStr, jsonSerializerSettings);
What is an elegant way to handle this situation, with minimal code changes.

Your Object representation for the normal Json should be something like this :
using J = Newtonsoft.Json.JsonPropertyAttribute;
public partial class Data
{
[J("isDemo")] public bool? IsDemo { get; set; }
[J("Asynchronous")] public bool? IsAsynchronous { get; set; }
[J("OrderId")] public string OrderId { get; set; }
[J("CustomerReference")] public string CustomerReference { get; set; }
[J("Fee")] public double? Fee { get; set; }
}
While having a custom JsonConverter handeling the whole Xml representation will be nice. I find it difficult to write and maintain.
You should divide and conquer:
Generate a class that is the representation of the Xml-ish Json.
Remove unnecessary property, keep Xml "nil" where needed
Create simple custom converter for mapping string representation to the correct type.
eg: "true" => bool, "123" => int,
public partial class XmlRepresentation
{
[J("isDemo")] public BoolWrapper IsDemo { get; set; }
[J("Asynchronous")] public BoolWrapper Asynchronous { get; set; }
[J("Fee")] public DoubleWrapper Fee { get; set; }
[J("CustomerReference")] public StringWrapper CustomerReference { get; set; }
[J("OrderId")] public string OrderId { get; set; }
}
public partial class NullableXmlValue
{
[J("#xsi:nil")][JsonConverter(typeof(BoolParseStringConverter))]
public bool IsNull { get; set; }
}
public partial class BoolWrapper :NullableXmlValue
{
[J("#text")][JsonConverter(typeof(BoolParseStringConverter))]
public bool Value { get; set; }
}
public partial class StringWrapper :NullableXmlValue
{
[J("#text")] public string Value { get; set; }
}
public partial class DoubleWrapper :NullableXmlValue
{
[J("#text")][JsonConverter(typeof(DoubleParseStringConverter))]
public double Value { get; set; }
}
With some simple String to Type {Bool, Double} parser:
internal class BoolParseStringConverter : JsonConverter
{
public override bool CanConvert(Type t) => t == typeof(bool) || t == typeof(bool?);
public override object ReadJson(JsonReader reader, Type t, object existingValue, JsonSerializer serializer)
{
if (reader.TokenType == JsonToken.Null) return null;
var value = serializer.Deserialize<string>(reader);
if (Boolean.TryParse(value, out bool b))
{
return b;
}
throw new Exception("Cannot unmarshal type bool");
}
public override void WriteJson(JsonWriter writer, object untypedValue, JsonSerializer serializer)
{
if (untypedValue == null)
{
serializer.Serialize(writer, null);
return;
}
var value = (bool)untypedValue;
var boolString = value ? "true" : "false";
serializer.Serialize(writer, boolString);
return;
}
public static readonly BoolParseStringConverter Singleton = new BoolParseStringConverter();
}
internal class DoubleParseStringConverter : JsonConverter
{
public override bool CanConvert(Type t) => t == typeof(double) || t == typeof(double?);
public override object ReadJson(JsonReader reader, Type t, object existingValue, JsonSerializer serializer)
{
if (reader.TokenType == JsonToken.Null) return null;
var value = serializer.Deserialize<string>(reader);
if (Double.TryParse(value, out double l))
{
return l;
}
throw new Exception("Cannot unmarshal type long");
}
public override void WriteJson(JsonWriter writer, object untypedValue, JsonSerializer serializer)
{
if (untypedValue == null)
{
serializer.Serialize(writer, null);
return;
}
var value = (double)untypedValue;
serializer.Serialize(writer, value.ToString());
return;
}
public static readonly DoubleParseStringConverter Singleton = new DoubleParseStringConverter();
}
This way you can directly deserialize to XmlRepresentation and use a simple projection logic to get the Data.
public partial class XmlRepresentation
{
public Data ToDataType(){
var result = new Data();
if( !this.IsDemo?.IsNull ?? false)
result.IsDemo = this.IsDemo.Value;
// etc..
return result;
}
}
And for knowing if it's the normal Json or the Xml-ish one I will simply use a try catch.
That way I won't have to write complexe JsonConverter or class that represent both Normal and Xml-ish.

Please use like this in Model:
public class User
{
// always require a string value
[JsonProperty("name", Required = Required.Always)]
public string Name { get; set; }
// don't require any value
[JsonProperty("role", NullValueHandling = NullValueHandling.Ignore)]
public string Role { get; set; }
// property is ignored
[JsonIgnore]
public string Password { get; set; }
}
Result generated with Json.NET serialization attributes:
{
"type": "object",
"properties": {
"name": {
"type": "string"
},
"role": {
"type": [
"string",
"null"
]
}
},
"required": [
"name"
]
}

Deserialize property to different class based on other property c#

I know there are many similar questions on SO, however all the ones I've found require a shared base class in order to work.
With a stream of JSON data like this:
[
{
"webhookType": "order",
"data": {
"id": "eeiefj393",
"orderProperty": "Value"
}
},
{
"webhookType": "customer",
"data": {
"id": 29238,
"customerProperty": "Value"
}
}
]
I wish to deserialize this into two containers, List<Customer> and List<Order>. Where the two classes are as follows:
class Order
{
public string Id { get; set; }
public string OrderProperty { get; set; }
[...]
}
class Customer
{
public long Id { get; set; }
public string CustomerProperty { get; set; }
[...]
}
There may be shared property names however there are no shared properties + type between these two classes and so the solutions involing a sub class aren't working for me.

You need to create a JsonConverter.
DataConverter
public class WebHookConverter : 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)
{
if (reader.TokenType == JsonToken.StartObject)
{
JObject item = JObject.Load(reader);
if (item["webhookType"].Value<string>() == "order")
{
var webhook = new WebHook
{
Type = item["webhookType"].Value<string>(),
Data = item["data"].ToObject<Order>()
};
return webhook;
}
else if (item["webhookType"].Value<string>() == "customer")
{
var webhook = new WebHook
{
Type = item["webhookType"].Value<string>(),
Data = item["data"].ToObject<Customer>()
};
return webhook;
}
}
return null;
}
public override bool CanConvert(Type objectType)
{
throw new NotImplementedException();
}
}
Objects
[JsonConverter(typeof(WebHookConverter))]
public class WebHook
{
[JsonProperty("webhookType")]
public string Type { get; set; }
public object Data { get; set; }
}
public class Order
{
public string Id { get; set; }
[JsonProperty("orderProperty")]
public string Property { get; set; }
}
public class Customer
{
public long Id { get; set; }
[JsonProperty("customerProperty")]
public string Property { get; set; }
}
Serialization
var json = File.ReadAllText("json1.json");
var obj = JsonConvert.DeserializeObject<List<WebHook>>(json);
var orderList = obj.Where(o => o.Type == "order").Select(o => o.Data).ToList();
var customerList = obj.Where(o => o.Type == "customer").Select(o => o.Data).ToList();
Output:

How to deserialize name-value collection pairs from a JSON string into an object?

I am trying to deserialize a JSON string into a strongly typed Payment class as defined below. The JSON contains some name-value pairs in the items collection. How can I deserialize these into the ID and PersonName properties on my class?
My JSON:
{
"status": 1,
"amount": 200.0,
"items": [
{
"name": "ID",
"value": "123456"
},
{
"name": "PersonName",
"value": "test"
}
]
}
My class:
public class Payment
{
[DataMember]
public string Status { get; set; }
[DataMember]
public string Amount { get; set; }
[DataMember]
public string ID { get; set; }
[DataMember]
public string PersonName { get; set; }
}
Here is how I am trying to deserialize it:
var response = JsonConvert.DeserializeObject<Payment>(message);

You will need to use a custom JsonConverter to do what you want. Below is a generic one which should do the job. The converter works by first loading the JSON into a JObject, then converterting the items array into regular properties on the JObject, and finally populating the target class from the JObject.
public class ClassWithItemsConverter<T> : JsonConverter where T : class, new()
{
public override bool CanConvert(Type objectType)
{
return objectType == typeof(T);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
JObject jo = JObject.Load(reader);
JProperty items = jo.Property("items");
if (items != null && items.Value.Type == JTokenType.Array)
{
foreach (JObject item in items.Value.Children<JObject>())
{
jo.Add((string)item["name"], item["value"]);
}
items.Remove();
}
T result = new T();
serializer.Populate(jo.CreateReader(), result);
return result;
}
public override bool CanWrite
{
get { return false; }
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
throw new NotImplementedException();
}
}
You can use the converter by adding a [JsonConverter] attribute to your target class like this:
[JsonConverter(typeof(ClassWithItemsConverter<Payment>))]
public class Payment
{
...
}
Here is a working demo: https://dotnetfiddle.net/IuHT3O

Deserializing complex Json objects

I want to deserialize a complex and let's say not well constructed json. That code that I wrote doesn't deserialize the object, the MovieInfo property is null. You can find the example json in the code. I want to avoid using JObject.Parse and dynamic objects. What am I missing here?
using System.Collections.Generic;
using Newtonsoft.Json;
namespace ComplexJsonExample
{
class Program
{
static void Main(string[] args)
{
string jsonInText = #"
{
""movies"" : [
{
""Harry Potter"" : [
{ ""rating"": ""great""},
{ ""rating"": ""horrible""}
]
},
{
""Guardians of the galaxy"" : [
{ ""rating"": ""cool""},
{ ""rating"": ""awesome""}
]
}
]
}
";
var movieList = JsonConvert.DeserializeObject<MovieList>(jsonInText);
}
}
public class MovieList
{
[JsonProperty("movies")]
public IList<Movie> Movies { get; set; }
}
public class Movie
{
IDictionary<string, IList<MovieRating>> MovieInfo { get; set; }
}
public class MovieRating
{
[JsonProperty("rating")]
public string Rating { get; set; }
}
}

It's a bit ugly, but you can do it like this:
class MovieList
{
[JsonProperty("movies")]
public Movie[] Movies { get; set; }
}
class Movie : Dictionary<string, MovieRating[]>
{
}
class MovieRating
{
[JsonProperty("rating")]
public string Rating { get; set; }
}
It's weird that the movie is a dictionary with only one key (its title), but it matches the JSON structure. You can always map it to something more sensible after deserialization.

I consider this a bit of a hack, but it works, and deserializes your json string into the format you required:
class MovieConverter : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return objectType == typeof(Movie);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
var movie = new Movie(){
MovieInfo = new Dictionary<string,IList<MovieRating>>()
};
while (reader.Read() && reader.Value != null)
{
var name = (string)reader.Value;
reader.Read();
var ratings = ((JArray)serializer.Deserialize(reader)).Values<string>("rating");
movie.MovieInfo.Add(name, ratings.Select(r => new MovieRating(){ Rating = r}).ToList());
}
return movie;
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
throw new NotImplementedException();
}
}
I did have to make two changes to your original objects, first I made the accessor for MovieInfo public so I could access it, and second to add the JsonConverterAttribute:
[JsonConverter(typeof(MovieConverter))]
public class Movie
{
public IDictionary<string, IList<MovieRating>> MovieInfo { get; set; }
}

Modify the behaviour of JSON.NET to serialize a collection of objects to an array of IDs

I want to modify JSON.NET so that when I am serializing a Model from my API it sends only an array of IDs for a composite Collection object.
For example:
class Employee
{
public ICollection<Address> Addresses { get; set; }
}
class Address
{
public int id;
public string location;
public string postcode;
}
Then when I send that back through WebApi
Request.Createresponse(HttpStatusCode.OK, new Employee());
Instead of this:
{
"Addresses" :
[
{"id" : 1, "location" : "XX", "postcode" : "XX" },
{"id" : 2, "location" : "XX", "postcode" : "XX" }
]
}
It just sends as this:
{
"Addresss" : [1,2]
}
I want this to be happening application-wide and I don't want to modify at the specific place.
How can I achieve this using the JSON.NET serializer?

You can get the result you want using a custom JsonConverter such as this:
class IdOnlyListConverter : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return (typeof(IEnumerable).IsAssignableFrom(objectType) &&
objectType != typeof(string));
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
JArray array = new JArray();
foreach (object item in (IEnumerable)value)
{
PropertyInfo idProp = item.GetType().GetProperty("id");
if (idProp != null && idProp.CanRead)
{
array.Add(JToken.FromObject(idProp.GetValue(item, null)));
}
}
array.WriteTo(writer);
}
public override bool CanRead
{
get { return false; }
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
throw new NotImplementedException();
}
}
In your model, wherever you have a collection of something where you only want the IDs, decorate the collection property with a [JsonConverter] attribute specifying the custom converter. For example:
class Employee
{
public string name { get; set; }
[JsonConverter(typeof(IdOnlyListConverter))]
public ICollection<Address> Addresses { get; set; }
}
class Address
{
public int id { get; set; }
public string location { get; set; }
public string postcode { get; set; }
}
When the collection gets serialized, the converter will be used, and only the ID values will be written out. Demo:
class Program
{
static void Main(string[] args)
{
Employee emp = new Employee
{
name = "Joe",
Addresses = new List<Address>
{
new Address { id = 1, location = "foo", postcode = "bar" },
new Address { id = 2, location = "baz", postcode = "quux" }
}
};
string json = JsonConvert.SerializeObject(emp);
Console.WriteLine(json);
}
}
Output:
{"name":"Joe","Addresses":[1,2]}

Please have a look at Json.Net's documentation.
public class Address
{
[JsonProperty("Id")]
public int I'd { get; set; }
[JsonIgnore]
public string Location { get; set; }
[JsonIgnore]
public string PostalCode { get; set; }
}
The only drawback to this is that you'll never be able to serialize the Location and PostalCode properties to JSON should you ever want to.
I believe there is a way to specify the serialization that should be used when serializing to JSON with Json.Net. Again, have a look at their documentation.