How to serialize external classes into json with custom field names in Json.Net?

Question

I have an external data contract, which cannot be modified. Json is used to serialize these classes. I need to save on output data size, so I would like to change original fields names to their shorter versions, i.e.:

public ClassWithLongName
{
    public string FieldWithLongName = "field1";
    public string FieldWithEvenLongerName = "field2";
}

should be serialzed to something like:

{"f1" = "field1", "f2" = "field2"}

To have ability to deserialize it back properly, mapping between original and short names must be provided somehow (I was thinking about dictionary. Should I use CustomConverter or IContractResolver for that?

EDIT:

There is a way to do it using CustomContractResolver : DefaultContractResolver. I am overriding CreateProperty method to swap the property name. A the moment the problem is that I can't get serialized object type (so all the properties' names are being held in one common map, instead of separate maps per type). Do you know how can I get serialized object type from DefaultContractResolver?

EDIT2:

The type can be taken from ResolveContract method (it is passed as parameter here). I have achieved the functionality I needed, but there is one huge problem with it. Performance. I counted time elapsed fo serializing simple object 10000 times in a loop. For default serialization it was about 150ms and for custom serialization about 15s. Do you know if there is a way to avoid it. I suppose that the overhead is caused by reflection. But how can default serializer avoid it? I am using DefaultContractResolver as parent class for my CustomContractResolver, so it should use all the mechanisms that parent class is using..

user1968030 · Accepted Answer · 2014-02-19 19:24:48Z

1

Use anonymouse object:

ClassWithLongName obj = new ClassWithLongName();
var anonymouse  =  new { FieldWithLongName = obj.FieldWithEvenLongerName, FieldWithEvenLongerName = obj.FieldWithEvenLongerName };

JavaScriptSerializer serializer = new JavaScriptSerializer();
var output = serializer.Serialize(anonymouse);

answered Feb 19, 2014 at 19:24

user1968030

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3 Comments

rideronthestorm Over a year ago

And how would I deserialize objects? How would deserializer know which field in json corresponds to which field in c# object?

user1968030 Over a year ago

JsonConvert.DeserializeObject<type>(myjsondata);

rideronthestorm Over a year ago

And the first question should be: how whould the output looks like (and how can I customize it)?

Anthony Shaw · Accepted Answer · 2014-02-19 19:34:33Z

1

If you didn't want to use anonymous objects, you could create your own object and use AutoMapper to map the external data contract into your own class and then serialize that using JavaScriptSerializer classes

answered Feb 19, 2014 at 19:34

Anthony Shaw

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3 Comments

rideronthestorm Over a year ago

As mentioned in the title, I would like to use Json.Net library. Additionally at the moment copying objects (like Automapper does) is not an option. I am asking for possibilities of customization of serialization (and deserialization) in that specific library (Newtonsoft Json.Net).

Anthony Shaw Over a year ago

you are not going to be able to customize the output without having access to the classes. You will either need to map to your own classes and serialize or create an anonymous object and serialize that

rideronthestorm Over a year ago

I think there is a simple solution to it. I can use decorator pattern to decorate original properties with json attributes.

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