How to serialize class type but not the namespace to a Json string using DataContractJsonSerializer

Question

I\'m trying to serialize a class hierarchy to a Json string using DataContractJsonSerializer, in a WCF service. the default behaviour for serializing a derived clas

Answer 1

@Cheeso wrote:

To avoid this, you'd maybe need to return a string from the WCF method, perform the serialization yourself, and post-process the emitted JSON.

Here's how I implemented that post-processing. I thought I'd post it here JIC it might help someone else.

First some boilerplate to show how I generate my JSON string:

// Instantiate & populate the object to be serialized to JSON
SomeClass xyz = new SomeClass();
... populate it ...

// Now serialize it
DataContractJsonSerializer ser = new DataContractJsonSerializer(xyz.GetType()); // Note xyz.GetType()
... serialize the object to json, many steps omitted here for brevity ...
string json = sr.ReadToEnd();

(Serialization is based on examples from https://msdn.microsoft.com/en-us/library/bb412179%28v=vs.110%29.aspx )

Note that the [DataContract] on SomeClass does not include the (name="") syntax that I've seen suggested elsewhere. That only removes the namespace from the __type at the cost of needing to adorn ALL your DataContract attrs, which clutters your code. Instead, my post-processor handles the assembly name in the __type field.

And now the string json contains the JSON text, but unfortunately includes all that "__type" junk that you don't want but can't suppress.

So here's my post-processing code that removes it:

// This strips out that unsuppressable __type clutter generated by the KnownType attributes
Attribute[] attrs = Attribute.GetCustomAttributes(xyz.GetType());
foreach (Attribute attr in attrs)
{
    if (attr is KnownTypeAttribute)
    {
        KnownTypeAttribute a = (KnownTypeAttribute)attr;
        string find = "\"__type\":\"" + a.Type.ReflectedType.Name + "." + a.Type.Name + ":#" + a.Type.Namespace + "\",";
        json = json.Replace(find, "");
    }
}

This makes a few assumptions, most notably that the __type field ends with a comma, which assumes that another field follows it, though (a) my objects always have at least 1 field and (b) I've found that the __type field is always 1st in the serialized object's output.

As always, you may have to adjust something to your situation, but I find it works well for mine.