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Converter that uses generics to parse json model

I have a converter class that receives json in input, here are 2 valid examples:
{
"method": "Model",
"payload": {
"key": "value"
}
}
and
{
"method": "OtherModel",
"payload": {
"foo": "bar"
}
}
In C#, I have classes mapped to each possible model:
public class Model
{
public string Key { get; set; }
}
public class OtherModel
{
public string Foo { get; set; }
}
I need a generic converter
How can I use the string value in the method of the JSON to convert in a generic way the content of the payload field?
Is using a huge switch the only way? This is the prototype I have so far but there are hundreds of different models so it will grow quite large...
public IResult ParseJson(string json)
{
Regex regexMessageName = new Regex("\"messageName\": \"(.*?)\"", RegexOptions.Compiled);
var messageName = regexMessageName.Match(json).Groups[1].Value;
switch (messageName)
{
case "Model":
var raw = JsonConvert.DeserializeObject<JsonData<Model>>(json);
return new LogInfoRequestResult<Model> { Raw = raw };
case "OtherModel":
var raw = JsonConvert.DeserializeObject<JsonData<OtherModel>>(json);
return new LogInfoRequestResult<OtherModel> { Raw = raw };
}
}

If you want complete control of your classes, and allow them to evolve independently, then you can have one base class that owns the Method, and then as many subclasses as you want with their own definition of the payload.
First, parse into the baseclass, just to get a strongly typed deserialization of Method
Then, there are a lot of patterns to address branching logic.
If you have 1-2 cases, an if statement is fine
If you have 3-5 cases, you can use a switch
If you have 6-10 cases, you can create a dictionary that maps method name to class type
If you have more than that, you can use the strategy pattern and pass an interface around
Here's an example of how you could write the code:
var json = #"{
'method': 'Model',
'payload': {
'key': 'value'
}
}";
var modelBase = JsonConvert.DeserializeObject<ModelBase>(json);
var methodMapping = new Dictionary<string, Type>()
{
{MethodTypes.Model.ToString(), typeof(Model)},
{MethodTypes.OtherModel.ToString(), typeof(OtherModel)},
};
Type methodClass = methodMapping[modelBase.Method];
var result = JsonConvert.DeserializeObject(json, methodClass);
Note: Since we're programmatically determining the correct type, it's hard to pass to a generic <T>, so this uses the overload of DeserializeObject that takes type as a param
And here are the classes that model incoming messages
public enum MethodTypes
{
Model,
OtherModel
}
public class ModelBase
{
public string Method { get; set; }
}
public class Model : ModelBase
{
public ModelInfo Payload { get; set; }
public class ModelInfo
{
public string Key { get; set; }
}
}
public class OtherModel : ModelBase
{
public ModelInfo Payload { get; set; }
public class ModelInfo
{
public string Foo { get; set; }
}
}
Dictionary<string,string>
If your data is always going to be "foo":"bar" or "key":"value" .... string:string, then Cid's suggesting to use Dictionary<string,string> Payload makes a lot of sense. Then figure out however you want to map from that c# class in a c# constructor that returns whatever type you want.
Additional Resources:
How to handle both a single item and an array for the same property using JSON.net
Deserializing polymorphic json classes without type information using json.net
JSON.NET - Conditional Type Deserialization
Conditionally deserialize JSON string or array property to C# object using JSON.NET?

You can instanciate an object of the expected class using Activator.CreateInstance(), then populate it with JsonConvert.PopulateObject()
In example :
Type t = Type.GetType($"NameSpaceName.{messageName}"); // this must be a fully qualified name
object obj = Activator.CreateInstance(t);
JsonConvert.PopulateObject(json, obj);

How to use derived class for XML serialization?

I am converting my working XML serialization so that the model classes inherit from abstract base classes (to allow for future use of different serial formats).
My serialization as-is is working fine but when I switch to using models derived from a base class I get all kinds of exceptions so I'm unsure of how to proceed.
My class base class is:
namespace Data
{
public abstract class Configuration
{
public abstract string Schema { get; set; }
public abstract Command[] Commands { get; set; }
}
public abstract class Command
{
public abstract string Name { get; set; }
}
}
My derived concrete class (the class that is working just fine before it was derived) is then in a child namespace:
namespace Data.Xml
{
[Serializable()]
[XmlType(AnonymousType = true)]
[XmlRoot(Namespace = "", IsNullable = false)]
public class Configuration : Data.Configuration
{
[XmlAttribute("noNamespaceSchemaLocation",
Namespace = System.Xml.Schema.XmlSchema.InstanceNamespace)]
public override string Schema { get; set; }
[XmlArrayItem("Command", IsNullable = false)]
public override Data.Command[] Commands { get; set; }
}
[Serializable()]
public class Command : Data.Command
{
public override string Name { get; set; }
}
}
I call the serializer within that child namespace like so:
public override Data.Configuration DeserializeConfig(StreamReader config)
{
var cs = new XmlSerializer(typeof(Configuration),
new Type[] { typeof(Command) });
return (Configuration)ConfigSerializer.Deserialize(ConfigStreamReader);
}
public override string SerializeConfig(Data.Configuration c, Encoding encoding)
{
string Output = null;
var Stream = new MemoryStream();
using (var Writer = new XmlTextWriter(Stream, encoding))
{
Writer.Formatting = Formatting.Indented;
XmlSerializerNamespaces ns = new XmlSerializerNamespaces();
ns.Add("xsi", XmlSchema.InstanceNamespace);
(new XmlSerializer(typeof(Configuration))).Serialize(Writer, c, ns);
Output = encoding.GetString(Stream.ToArray());
}
Stream.Dispose();
return Output;
}
The resulting XML should look like:
<?xml version="1.0" encoding="utf-8"?>
<Configuration
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="SomeSchema.xsd">
<Commands>
<Command>
<Name>SomeNameValue</Name>
</Command>
</Commands>
</Configuration>
I am seeing the following exception when attempting to instantiate the serializer (first line in DeserializeConfig() method above):
InvalidOperationException: Types 'Data.Command' and 'Data.Xml.Command' both use the XML type name, 'Command', from namespace ''. Use XML attributes to specify a unique XML name and/or namespace for the type.
I'm not really sure why the serializer is trying to create something from the base class, sure the names are the same, that's kind of the idea of derivation and namespaces etc ... How do I properly mark this up with attributes to have it de/serialize properly?
FYI: I did see several questions already on this, but the answers all seemed specific enough to the askers requirements that I could not work out how to apply the information to this, seemingly simple, scenario.
Update: I figured out how to pass included types into the serializer at instantiation instead of having to annotate the base class so I have removed that part from my question and updated the code. This outdates bruno's suggestion and my response (although the suggested question still does not apply).
Update: I attempted to separate the names in XML namespaces by adding the derived class to a namespace (i.e. adding [XmlElement(Namespace = "http://www.foo.com/data/xml")] to each property in the derived class) but this made no difference as the serializer still seems to "see" both the base and derived class together and so thinks they're both in that namespace.

Finally flipping figured most of this out.
I stepped back and started with a very simple working non-derived example and worked up to what I needed.
There were two things going on here. First the clashing type names, then the clashing property names. While I had bits of each of these right, the amount of permutations of options for structuring each when combined together had me confused.
To prevent the abstract and derived type names from clashing when serialized I needed to make the derived class type anonymous (here using the XmlType attribute).
To stop the property names clashing I needed to ignore both the property in the derived class and the base class. To do this without editing the base class I was missing a vital piece, XmlAttributeOverrides. I had seen this mentioned in the MSDN documentation for XmlSerializer.Serialize() but the information there was pretty minimal in explaining what it pertained to. This answer to another question led me to David Woodward's excellent explanation.
I have yet to try any of this with a derived type list property, or with deserialization.
Below is complete basic example of a program that outputs a string with some serialized XML on the console output:
using System;
using System.Text;
using System.IO;
using System.Xml;
using System.Xml.Serialization;
namespace Test
{
class Program
{
static void Main(string[] args)
{
var TestBar = new MyXml.Bar()
{
Name = "John Smith",
};
Serializer s = new MyXml.Serializer();
var TestOutput = s.Serialize(TestBar);
Console.WriteLine(TestOutput);
}
}
public abstract class Bar
{
public abstract string Name { get; set; }
}
public abstract class Serializer
{
public abstract string Serialize(Bar bar);
}
namespace MyXml
{
public class Serializer : Test.Serializer
{
public override string Serialize(Test.Bar bar)
{
string Output = null;
var Stream = new MemoryStream();
var Encoding = new UTF8Encoding(false, true);
// Ignore the Name property in the *base* class!
var ao = new XmlAttributeOverrides();
var a = new XmlAttributes();
a.XmlElements.Clear(); // Clear any element attributes
a.XmlAttribute = null; // Remove any attribute attributes
a.XmlIgnore = true; // Set the ignore attribute value true
ao.Add(typeof(Test.Bar), "Name", a); // Set to use with Test.Bar.Name
using (var Writer = new XmlTextWriter(Stream, Encoding))
{
Writer.Formatting = Formatting.Indented;
var s = new XmlSerializer(typeof(Bar), ao);
s.Serialize(Writer, bar);
Output = Encoding.GetString(Stream.ToArray());
}
Stream.Dispose();
return Output;
}
}
[Serializable]
[XmlType(AnonymousType = true)] // Make type anonymous!
[XmlRoot(IsNullable = false)]
public class Bar : Test.Bar
{
[XmlIgnore] // Ignore the Name property in the *derived* class!
public override string Name
{
get => Unreverse(ReverseName);
set => ReverseName = Reverse(value);
}
[XmlElement("Name", IsNullable = false)]
public string ReverseName { get; set; }
private string Unreverse(string name)
{
return "John Smith"; // Smith, John -> John Smith
}
private string Reverse(string name)
{
return "Smith, John"; // John Smith -> Smith, John
}
}
}
}

Serialize list of interface types with ServiceStack.Text

I'm looking at ways to introduce something other than BinaryFormatter serialization into my app to eventually work with Redis. ServiceStack JSON is what I would like to use, but can it do what I need with interfaces?
It can serialize (by inserting custom __type attribute)
public IAsset Content;
but not
public List<IAsset> Contents;
- the list comes up empty in serialized data. Is there any way to do this - serialize a list of interface types?
The app is big and old and the shape of objects it uses is probably not going to be allowed to change.
Thanks

Quoting from http://www.servicestack.net/docs/framework/release-notes
You probably don't have to do much :)
The JSON and JSV Text serializers now support serializing and
deserializing DTOs with Interface / Abstract or object types. Amongst
other things, this allows you to have an IInterface property which
when serialized will include its concrete type information in a __type
property field (similar to other JSON serializers) which when
serialized populates an instance of that concrete type (provided it
exists).
[...]
Note: This feature is automatically added to all
Abstract/Interface/Object types, i.e. you don't need to include any
[KnownType] attributes to take advantage of it.
By not much:
public interface IAsset
{
string Bling { get; set; }
}
public class AAsset : IAsset
{
public string Bling { get; set; }
public override string ToString()
{
return "A" + Bling;
}
}
public class BAsset : IAsset
{
public string Bling { get; set; }
public override string ToString()
{
return "B" + Bling;
}
}
public class AssetBag
{
[JsonProperty(TypeNameHandling = TypeNameHandling.None)]
public List<IAsset> Assets { get; set; }
}
class Program
{
static void Main(string[] args)
{
try
{
var bag = new AssetBag
{
Assets = new List<IAsset> {new AAsset {Bling = "Oho"}, new BAsset() {Bling = "Aha"}}
};
string json = JsonConvert.SerializeObject(bag, new JsonSerializerSettings()
{
TypeNameHandling = TypeNameHandling.Auto
});
var anotherBag = JsonConvert.DeserializeObject<AssetBag>(json, new JsonSerializerSettings()
{
TypeNameHandling = TypeNameHandling.Auto
});

How to Customize Deserialization of a JSON enum in .NET?

I have the following sample C# code that is auto-genereated from an xsd using the svcutils.exe application.
[DataContract]
public enum Foo
{
[EnumMember(Value = "bar")]
Bar = 1,
[EnumMember(Value = "baz")]
Baz = 2
}
[DataContract]
public class UNameIt
{
[DataMember(Name = "id")]
public long Id { get; private set; }
[DataMember(Name = "name")]
public string Name { get; private set; }
[DataMember(Name = "foo")]
public Foo Foo { get; private set; }
}
The following is a unit test that attempts to deserialise a sample JSON document to the UNameIt class.
[TestClass]
public class JsonSerializer_Fixture
{
public const string JsonData = #"{ ""id"":123456,
""name"":""John Doe"",
""foo"":""Bar""}";
[TestMethod]
public void DataObjectSimpleParseTest()
{
DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(UNameIt));
MemoryStream ms = new MemoryStream(Encoding.Unicode.GetBytes(JsonData));
UNameIt dataObject = serializer.ReadObject(ms) as UNameIt;
Assert.IsNotNull(dataObject);
Assert.AreEqual(123456, dataObject.Id);
Assert.AreEqual(Foo.Baz, dataObject.Foo);
}
}
Unfortunately, the test fails giving the following reason:
System.Runtime.Serialization.SerializationException: There was an
error deserializing the object of type MyNamespace.Units.UNameIt. The
value 'Bar' cannot be parsed as the type 'Int64'.
The test will pass if I update my JSON string to replace the string specifier for the Enum to an integer e.g.
public const string JsonData = #"{ ""id"":123456,
""name"":""John Doe"",
""foo"":""1""}";
I do not have the flexibility to the change the supplied JSON so I have to figure out how to convert the string Enum representation perhaps on serialisation. Ideally, I would like to facilitate this without having to change my autogenerate class because once I re-generate the class I would loose my changes.
I am wondering if it would be possible to extend the DataContractJsonSerializer to custom handle Enumerations? Or perhaps there is better way to do this?

This behavior is by design. Here's a quote from the Enumerations and JSON paragraph on MSDN:
Enumeration member values are treated as numbers in JSON, which is
different from how they are treated in data contracts, where they are
included as member names.
Moreover the DataContractJsonSerializer will automatically serialize all enumerations, so the EnumMemberAttribute is actually ignored.
For a workaround, take a look at this answer on SO.

This is work :
var ret = new JavaScriptSerializer().Deserialize<tblGridProjects>(retApi.Item2);
But you can't use datamembers attributes, so can't rename properties.
You must set the name of the property like Json sended.

Json.net serialize/deserialize derived types?

json.net (newtonsoft)
I am looking through the documentation but I can't find anything on this or the best way to do it.
public class Base
{
public string Name;
}
public class Derived : Base
{
public string Something;
}
JsonConvert.Deserialize<List<Base>>(text);
Now I have Derived objects in the serialized list. How do I deserialize the list and get back derived types?

You have to enable Type Name Handling and pass that to the (de)serializer as a settings parameter.
Base object1 = new Base() { Name = "Object1" };
Derived object2 = new Derived() { Something = "Some other thing" };
List<Base> inheritanceList = new List<Base>() { object1, object2 };
JsonSerializerSettings settings = new JsonSerializerSettings { TypeNameHandling = TypeNameHandling.All };
string Serialized = JsonConvert.SerializeObject(inheritanceList, settings);
List<Base> deserializedList = JsonConvert.DeserializeObject<List<Base>>(Serialized, settings);
This will result in correct deserialization of derived classes. A drawback to it is that it will name all the objects you are using, as such it will name the list you are putting the objects in.

If you are storing the type in your text (as you should be in this scenario), you can use the JsonSerializerSettings.
See: how to deserialize JSON into IEnumerable<BaseType> with Newtonsoft JSON.NET
Be careful, though. Using anything other than TypeNameHandling = TypeNameHandling.None could open yourself up to a security vulnerability.

Since the question is so popular, it may be useful to add on what to do if you want to control the type property name and its value.
The long way is to write custom JsonConverters to handle (de)serialization by manually checking and setting the type property.
A simpler way is to use JsonSubTypes, which handles all the boilerplate via attributes:
[JsonConverter(typeof(JsonSubtypes), "Sound")]
[JsonSubtypes.KnownSubType(typeof(Dog), "Bark")]
[JsonSubtypes.KnownSubType(typeof(Cat), "Meow")]
public class Animal
{
public virtual string Sound { get; }
public string Color { get; set; }
}
public class Dog : Animal
{
public override string Sound { get; } = "Bark";
public string Breed { get; set; }
}
public class Cat : Animal
{
public override string Sound { get; } = "Meow";
public bool Declawed { get; set; }
}

Use this JsonKnownTypes, it's very similar way to use, it just add discriminator to json:
[JsonConverter(typeof(JsonKnownTypeConverter<BaseClass>))]
[JsonKnownType(typeof(Base), "base")]
[JsonKnownType(typeof(Derived), "derived")]
public class Base
{
public string Name;
}
public class Derived : Base
{
public string Something;
}
Now when you serialize object in json will be add "$type" with "base" and "derived" value and it will be use for deserialize
Serialized list example:
[
{"Name":"some name", "$type":"base"},
{"Name":"some name", "Something":"something", "$type":"derived"}
]

just add object in Serialize method
var jsonMessageBody = JsonSerializer.Serialize<object>(model);