I did search on So but it looks like for this type of json serializer there isnt much info out there. I'm using original version since I need 4.5 NET target: https://github.com/neuecc/Utf8Json
I have a custom object that needs custom serialization/deserialization logic:
public class CustomInstanceFormatter : IJsonFormatter<CustomInstance>
{
public void Serialize(ref JsonWriter writer, CustomInstance value, IJsonFormatterResolver formatterResolver)
{
if (value == null) { writer.WriteNull(); return; }
writer.WriteString(value.name);
formatterResolver.GetFormatterWithVerify<SomeNamespace.Data>().Serialize(ref writer, value.color, formatterResolver);
}
public CustomInstance Deserialize(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
{
if (reader.ReadIsNull()) return null;
var inst = new CustomInstance(reader.ReadString());
inst.color = formatterResolver.GetFormatterWithVerify<SomeNamespace.Data>().Deserialize(ref reader, formatterResolver);
return inst;
}
}
My problem is that the short readme does not explain anywhere how can I consume it. With NewtonSoft JSON it is fairly simple, but here I'm at a loss. JsonSerializer in both of his methods for Serialize/Deserialize only accepts a IJsonResolver.
You have to create your own Resolver which consumes your Formatter like this:
public class StandardFunctionResolver : IJsonFormatterResolver
{
public static StandardFunctionResolver Instance = new StandardFunctionResolver();
public Dictionary<Type, IJsonFormatter> formatters;
private StandardFunctionResolver ()
{
formatters = new Dictionary<Type, IJsonFormatter>()
{
{typeof(CustomInstance), new CustomInstanceFormatter()},
};
}
public IJsonFormatter<T> GetFormatter<T>()
{
if (formatters.TryGetValue(typeof(T), out var typeFormatter))
{
return (IJsonFormatter<T>)typeFormatter;
}
return StandardResolver.Default.GetFormatter<T>();
}
}
and then let UTF8Json consume it on Serialization or Deserialization like:
var idk = Utf8Json.JsonSerializer.ToJsonString(obj, StandardFunctionResolver.Instance);
Related
I'm currently working on a project where I need to fetch a large amount of data from the Database and parse it into a specific Json format, I already have built my custom Serializers and Its working properly when i pass a List to Gson. But as I was already working with Streams from my JPA Layer, I thought I could pass the Stream down to the Gson parser so that it could transform it directly to my Json data. But I'm getting an empty Json object instead of a correctly populated one.
So, if anyone could point to me a way to make Gson work with Java 8 Streams or if this isn't possible currently.. i could not find anything on Google, so i came to Stackoverflow.
You could use JsonWriter to streaming your data to output stream:
public void writeJsonStream(OutputStream out, Stream<DataObject> data) throws IOException {
try(JsonWriter writer = new JsonWriter(new OutputStreamWriter(out, "UTF-8"))) {
writer.setIndent(" ");
writer.beginArray();
data.forEach(d -> {
d.beginObject();
d.name("yourField").value(d.getYourField());
....
d.endObject();
});
writer.endArray();
}
}
Note that you're in charge of controling the json structure.
That is, if your DataObject contains nested Object, you have to write beginObject()/endObject() respectively. The same goes for nested array.
It is not as trivial as one would expect, but it can be done in a generic way.
When you look into the Javadoc to TypeAdapterFactory, they provide a very simplistic way of writing a TypeAdapterFactory for a custom type. Alas, it does not work as expected because of problems with element type detection. The proper way to do this can be found in Gson-internal CollectionTypeAdapterFactory. It is quite complex, but taking what's necessary one can come up with something like that:
final class StreamTypeAdapterFactory implements TypeAdapterFactory {
#SuppressWarnings("unchecked")
#Override
public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {
Type type = typeToken.getType();
Class<? super T> rawType = typeToken.getRawType();
if (!Stream.class.isAssignableFrom(rawType)) {
return null;
}
Type elementType = ExtraGsonTypes.getStreamElementType(type, rawType);
TypeAdapter<?> elementAdapter = gson.getAdapter(TypeToken.get(elementType));
return (TypeAdapter<T>) new StreamTypeAdapter<>(elementAdapter);
}
private static class StreamTypeAdapter<E> extends TypeAdapter<Stream<E>> {
private final TypeAdapter<E> elementAdapter;
StreamTypeAdapter(TypeAdapter<E> elementAdapter) {
this.elementAdapter = elementAdapter;
}
public void write(JsonWriter out, Stream<E> value) throws IOException {
out.beginArray();
for (E element : iterable(value)) {
elementAdapter.write(out, element);
}
out.endArray();
}
public Stream<E> read(JsonReader in) throws IOException {
Stream.Builder<E> builder = Stream.builder();
in.beginArray();
while (in.hasNext()) {
builder.add(elementAdapter.read(in));
}
in.endArray();
return builder.build();
}
}
private static <T> Iterable<T> iterable(Stream<T> stream) {
return stream::iterator;
}
}
The ExtraGsonTypes is a special class that I used to circumvent package-private access to $Gson$Types.getSupertype method. It's a hack that works if you're not using JDK 9's modules - you simply place this class in the same package as $Gson$Types:
package com.google.gson.internal;
import java.lang.reflect.*;
import java.util.stream.Stream;
public final class ExtraGsonTypes {
public static Type getStreamElementType(Type context, Class<?> contextRawType) {
return getContainerElementType(context, contextRawType, Stream.class);
}
private static Type getContainerElementType(Type context, Class<?> contextRawType, Class<?> containerSupertype) {
Type containerType = $Gson$Types.getSupertype(context, contextRawType, containerSupertype);
if (containerType instanceof WildcardType) {
containerType = ((WildcardType)containerType).getUpperBounds()[0];
}
if (containerType instanceof ParameterizedType) {
return ((ParameterizedType) containerType).getActualTypeArguments()[0];
}
return Object.class;
}
}
(I filed an issue about that in GitHub)
You use it in the following way:
Gson gson = new GsonBuilder()
.registerTypeAdapterFactory(new StreamTypeAdapterFactory())
.create();
System.out.println(gson.toJson(Stream.of(1, 2, 3)));
Is there a way to serialize an object so that it could then be rehydrated by .Net Core Configuration Binder?
Basically, I'd like to get this Test to pass:
[Test]
public void Can_Serialize_And_Rehydrate()
{
var foo = new Foo{ Prop1 = 42; Prop2 = "Test" }
Dictionary<string, string> serialized = Serialize(Foo);
var deserializedFoo = new Foo();
new ConfigurationBuilder()
.AddInMemoryCollection(serialized)
.Build()
.Bind(deserializedFoo);
Assert.AreEqual(deserializedFoo.Prop1, 42);
Assert.AreEqual(deserializedFoo.Prop2, "Test");
}
Is there a Serializer out-of-the-box, or am I'm going to need to write my own Serialize() method?
AddInMemoryCollection's signature is like below, so why are you trying to serialize your dictionary here? You could just use it as it is.
public static IConfigurationBuilder AddInMemoryCollection(
this IConfigurationBuilder configurationBuilder,
IEnumerable<KeyValuePair<string, string>> initialData)
If you like to know more about how to test your custom configurations, I would suggest to look here:
https://github.com/aspnet/Configuration/blob/1.0.0/test/Microsoft.Extensions.Configuration.Binder.Test/ConfigurationBinderTests.cs
I was able to get this working by "hijacking" a JsonConfigurationProvider and plugging serialized Json directly into it. Not sure if this is the best way, but it does work:
public class ConfigurationSerializer
{
private class CustomJsonProvider : JsonConfigurationProvider
{
public CustomJsonProvider() : base(new JsonConfigurationSource())
{
}
public IDictionary<string, string> GetData(Stream s)
{
Load(s);
// Return the Configuration Dictionary
return Data;
}
}
public Dictionary<string, string> Serialize(object o)
{
var serialized =
JsonConvert.SerializeObject(
o,
new JsonSerializerSettings {NullValueHandling = NullValueHandling.Ignore});
using (var ms = new MemoryStream(Encoding.UTF8.GetBytes(serialized)))
{
var jsonProvider = new CustomJsonProvider();
return jsonProvider
.GetData(ms)
.ToDictionary(key => key.Key, value => value.Value);
}
}
}
I'm currently doing some work on an API where I'm Casting an object before serializing it and returning the JSON. I expected the JSON result to be that of the Cast object and not the Uncast object, however I get all the properties in my JSON from the Uncast object
Example code
using System;
using Newtonsoft.Json;
namespace JSONSerializationOfCastObject
{
class Program
{
static void Main(string[] args)
{
B InstanceB = new B(){PropA = "A",PropB = "B"};
A InstanceA = InstanceB;
var JSONInstanceA = JsonConvert.SerializeObject(InstanceA);
Console.WriteLine(JSONInstanceA);
Console.ReadLine();
}
}
public class A
{
public string PropA { get; set; }
}
public class B:A
{
public string PropB { get; set; }
}
}
Result
{"PropB":"B","PropA":"A"}
Expected result
{"PropA":"A"}
Another example where the type just isn't what you expect
B InstanceB = new B(){PropA = "A",PropB = "B"};
A InstanceA = InstanceB;
var x = InstanceA.GetType() == typeof(A); //==> False but we casted it to A
I just cannot figure this out, NewtonSoft must do some reflection under the hood.
GitHub Example here: https://github.com/tharris29/JSONSerializationOfCastObject/tree/master
update
So I understand this is to do with reflection but just seems an odd result. Is there a way to tell the serializer what object type to use for serialization?
Just because you have assigned a B to an A does not mean that it is no longer a B. You can see this for yourself if you print out the type of your InstanceA variable after the assignment:
B instanceB = new B() { PropA = "A", PropB = "B" };
A instanceA = instanceB;
Console.WriteLine(instanceA.GetType().Name);
As you will see, the result is B.
Json.Net uses reflection to look at the actual type of an object and get all of its properties. As far as I know, it does not have a built-in way to limit the properties to just those of a base type. If you want to do that, you will need a custom JsonConverter. Here is one that might work for you (notice it also uses reflection):
public class BaseTypeConverter<T> : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return typeof(T).IsAssignableFrom(objectType);
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
T instance = (T)value;
JObject obj = new JObject();
foreach (PropertyInfo prop in typeof(T).GetProperties())
{
if (prop.CanRead)
{
obj.Add(prop.Name, JToken.FromObject(prop.GetValue(instance)));
}
}
obj.WriteTo(writer);
}
public override bool CanRead
{
get { return false; }
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
throw new NotImplementedException();
}
}
You can use this converter like this:
B instanceB = new B() { PropA = "A", PropB = "B" };
// serialize B, but only include the properties from type A
string json = JsonConvert.SerializeObject(instanceB, new BaseTypeConverter<A>());
Console.WriteLine(json);
Output:
{"PropA":"A"}
How to force WCF Rest client to use Json deserializer regardless of content-type?
I am invoking a REST based web service through WCF.
The service returns JSON body, but has content-type "Application/xml". The WCF framework is now giving me the XmlException.
public class MessageFormatter : IClientMessageFormatter
{
private readonly IClientMessageFormatter _formatter;
public MessageFormatter(IClientMessageFormatter formatter)
{
_formatter = formatter;
}
public object DeserializeReply(System.ServiceModel.Channels.Message message, object[] parameters)
{
return _formatter.DeserializeReply(message, parameters);
}
}
that _formatter.DeserializeReply is throwing XmlException. I can't find any example anywhere to force json deserialization on reply.
Edit - The "message" object when moused over is throwing "{... Error reading body: System.Xml.XmlException: The data at the root level is invalid. Line 1, position 1. ...}"
That same object in another one of my project that communicate with a different REST service (Picasa web services) has a what seems like a xml serialised version of JSON object?? So the problem seems further up the stream. I need to find where this object is originating from. I'll go play around with MessageEncoder class.
Edit - (Adding more info)
public class MyBinding : WebHttpBinding
{
public MyBinding(WebHttpSecurityMode mode)
: base(mode)
{
}
public override BindingElementCollection CreateBindingElements()
{
var result = base.CreateBindingElements();
var replacements = result.OfType<MessageEncodingBindingElement>().ToList();
foreach (var messageEncodingBindingElement in replacements)
{
var index = result.IndexOf(messageEncodingBindingElement);
result.Remove(messageEncodingBindingElement);
result.Insert(index, new MyMessageEncodingBindingElement(messageEncodingBindingElement));
}
return result;
}
}
public class MyMessageEncodingBindingElement : MessageEncodingBindingElement
{
private readonly MessageEncodingBindingElement _element;
public MyMessageEncodingBindingElement(MessageEncodingBindingElement element)
{
_element = element;
}
public override BindingElement Clone()
{
var result = _element.Clone();
if (result is MessageEncodingBindingElement)
return new MyMessageEncodingBindingElement(result as MessageEncodingBindingElement);
return result;
}
public override MessageEncoderFactory CreateMessageEncoderFactory()
{
return new MyMessageEncoderFactory(_element.CreateMessageEncoderFactory());
}
}
The method CreateMessageEncoderFactory() is never called even when the constructor and Clone method are hit when breakpoints are set. Any help? I'm trying to set a custom MessageEncoder and MessageEncoderFactory class to modify the instantiation process of the Message object.
You can use a WebContentTypeMapper for that. That's a property of the WebHttpBinding, and you can customize how the deserialization will be done by the encoder from that binding, including forcing it to always use the JSON deserializer, regardless of the incoming message's Content-Type. The code below shows how this can be done.
public class StackOverflow_13225272
{
[DataContract]
public class Person
{
[DataMember]
public string Name { get; set; }
[DataMember]
public int Age { get; set; }
public override string ToString()
{
return string.Format("Person[Name={0},Age={1}]", Name, Age);
}
}
[ServiceContract]
public interface ITest
{
[WebGet(ResponseFormat = WebMessageFormat.Json)]
Person GetPerson(string responseContentType);
}
public class Service : ITest
{
public Person GetPerson(string responseContentType)
{
WebOperationContext.Current.OutgoingResponse.ContentType = responseContentType;
return new Person { Name = "John Doe", Age = 29 };
}
}
class AllJsonContentTypeMapper : WebContentTypeMapper
{
public override WebContentFormat GetMessageFormatForContentType(string contentType)
{
return WebContentFormat.Json;
}
}
public static void Test()
{
string baseAddress = "http://" + Environment.MachineName + ":8000/Service";
WebServiceHost host = new WebServiceHost(typeof(Service), new Uri(baseAddress));
host.Open();
Console.WriteLine("Host opened");
#if USE_NETFX4
// This works on .NET 4.0 and beyond
WebHttpBinding binding = new WebHttpBinding();
binding.ContentTypeMapper = new AllJsonContentTypeMapper();
#else
// This works on .NET 3.5
CustomBinding binding = new CustomBinding(new WebHttpBinding());
binding.Elements.Find<WebMessageEncodingBindingElement>().ContentTypeMapper = new AllJsonContentTypeMapper();
ChannelFactory<ITest> factory = new ChannelFactory<ITest>(binding, new EndpointAddress(baseAddress));
#endif
ChannelFactory<ITest> factory = new ChannelFactory<ITest>(binding, new EndpointAddress(baseAddress));
factory.Endpoint.Behaviors.Add(new WebHttpBehavior());
ITest proxy = factory.CreateChannel();
Console.WriteLine("With JSON: {0}", proxy.GetPerson("application/json"));
Console.WriteLine("With XML: {0}", proxy.GetPerson("application/xml"));
Console.Write("Press ENTER to close the host");
Console.ReadLine();
host.Close();
}
}
This might work.
public class ForceJsonClientMessageFormatter : IClientMessageFormatter
{
private readonly DataContractJsonSerializer _jsonSerializer;
public ForceJsonClientMessageFormatter(Type responseType)
{
_jsonSerializer = new DataContractJsonSerializer(responseType);
}
public Message SerializeRequest(MessageVersion messageVersion, object[] parameters)
{
throw new NotImplementedException("This client message formatter is for replies only!");
}
public object DeserializeReply(Message message, object[] parameters)
{
string messageBody = message.GetBody<string>();
using (MemoryStream messageStream = new MemoryStream(Encoding.UTF8.GetBytes(messageBody)))
{
messageStream.Seek(0, SeekOrigin.Begin);
object deserializedObject = _jsonSerializer.ReadObject(messageStream);
return deserializedObject;
}
}
}
public class ForceJsonWebHttpBehavior : WebHttpBehavior
{
protected override IClientMessageFormatter GetReplyClientFormatter(OperationDescription operationDescription, ServiceEndpoint endpoint)
{
return new ForceJsonClientMessageFormatter(operationDescription.Messages[1].Body.ReturnValue.Type);
}
}
I haven't tried it, but I think this will work. You can create a custom IClientMessageFormatter which overwrites the message format to Json, wrap that in a behavior, and then apply that behavior to your client endpoint configuration.
public class ForceJsonClientMessageFormatterDecorator : IClientMessageFormatter
{
private readonly IClientMessageFormatter _decoratedFormatter;
public ForceJsonClientMessageFormatterDecorator(IClientMessageFormatter decoratedFormatter)
{
_decoratedFormatter = decoratedFormatter;
}
public object DeserializeReply(Message message, object[] parameters)
{
message.Properties[WebBodyFormatMessageProperty.Name] = new WebBodyFormatMessageProperty(WebContentFormat.Json);
return _decoratedFormatter.DeserializeReply(message, parameters);
}
public Message SerializeRequest(MessageVersion messageVersion, object[] parameters)
{
return _decoratedFormatter.SerializeRequest(messageVersion, parameters);
}
}
public class ForceJsonWebHttpBehavior : WebHttpBehavior
{
protected override IClientMessageFormatter GetReplyClientFormatter(OperationDescription operationDescription, ServiceEndpoint endpoint)
{
IClientMessageFormatter decoratedFormatter = base.GetReplyClientFormatter(operationDescription, endpoint);
return new ForceJsonClientMessageFormatterDecorator(decoratedFormatter);
}
}
First, I have a very simple java bean which can be easily serialized to json:
class Node {
private String text;
// getter and setter
}
Node node = new Node();
node.setText("Hello");
String json = new Gson().toJson(node);
// json is { text: "Hello" }
Then in order to make such beans have some dynamic values, so I create a "WithData" base class:
Class WithData {
private Map<String, Object> map = new HashMap<String, Object>();
public void setData(String key, Object value) { map.put(key, value); }
public Object getData(String key) = { return map.get(key); }
}
class Node extends WithData {
private String text;
// getter and setter
}
Now I can set more data to a node:
Node node = new Node();
node.setText("Hello");
node.setData("to", "The world");
But Gson will ignore the "to", the result is still { text: "Hello" }. I expect it to be: { text: "Hello", to: "The world" }
Is there any way to write a serializer for type WithData, that all classes extend it will not only generate its own properties to json, but also the data in the map?
I tried to implement a custom serializer, but failed, because I don't know how to let Gson serialize the properties first, then the data in map.
What I do now is creating a custom serializer:
public static class NodeSerializer implements JsonSerializer<Node> {
public JsonElement serialize(Node src,
Type typeOfSrc, JsonSerializationContext context) {
JsonObject obj = new JsonObject();
obj.addProperty("id", src.id);
obj.addProperty("text", src.text);
obj.addProperty("leaf", src.leaf);
obj.addProperty("level", src.level);
obj.addProperty("parentId", src.parentId);
obj.addProperty("order", src.order);
Set<String> keys = src.getDataKeys();
if (keys != null) {
for (String key : keys) {
obj.add(key, context.serialize(src.getData(key)));
}
}
return obj;
};
}
Then use GsonBuilder to convert it:
Gson gson = new GsonBuilder().
registerTypeAdapter(Node.class, new NodeSerializer()).create();
Tree tree = new Tree();
tree.addNode(node1);
tree.addNode(node2);
gson.toJson(tree);
Then the nodes in the tree will be converted as I expected. The only boring thing is that I need to create a special Gson each time.
Actually, you should expect Node:WithData to serialize as
{
"text": "Hello",
"map": {
"to": "the world"
}
}
(that's with "pretty print" turned on)
I was able to get that serialization when I tried your example. Here is my exact code
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import java.net.MalformedURLException;
import java.util.HashMap;
import java.util.Map;
public class Class1 {
public static void main(String[] args) throws MalformedURLException {
GsonBuilder gb = new GsonBuilder();
Gson g = gb.setPrettyPrinting().create();
Node n = new Node();
n.setText("Hello");
n.setData("to", "the world");
System.out.println(g.toJson(n));
}
private static class WithData {
private Map<String, Object> map = new HashMap<String, Object>();
public void setData(String key, Object value) { map.put(key, value); }
public Object getData(String key) { return map.get(key); }
}
private static class Node extends WithData {
private String text;
public Node() { }
public String getText() {return text;}
public void setText(String text) {this.text = text;}
}
}
I was using the JDK (javac) to compile - that is important because other compilers (those included with some IDEs) may remove the information on which Gson relies as part of their optimization or obfuscation process.
Here are the compilation and execution commands I used:
"C:\Program Files\Java\jdk1.6.0_24\bin\javac.exe" -classpath gson-2.0.jar Class1.java
"C:\Program Files\Java\jdk1.6.0_24\bin\java.exe" -classpath .;gson-2.0.jar Class1
For the purposes of this test, I put the Gson jar file in the same folder as the test class file.
Note that I'm using Gson 2.0; 1.x may behave differently.
Your JDK may be installed in a different location than mine, so if you use those commands, be sure to adjust the path to your JDK as appropriate.