Post empty body with Jersey 2 client

Question

How do I submit a post request with an empty body with a Jersey 2 client?

final MyClass result = ClientBuilder.newClient()
    .target("http://localhost:8080")
    .path("path")
    .queryParam("key", "value")
    .request(APPLICATION_JSON)
    .post(What to fill in here if the body should be left empty??, MyClass.class);

---

Update: this works:

final MyClass result = ClientBuilder
    .newBuilder().register(JacksonFeature).build()
    .target("http://localhost:8080")
    .path("path")
    .queryParam("key", "value")
    .request(APPLICATION_JSON)
    .post(null, MyClass.class);

Nozzle

I'm late to the party, but FWIW your update is the answer to my particular problem - specifically I don't want a Content-Type header :) – Goaltender

Answer 1

I can't find this in the doc's anywhere, but I believe you can use null to get an empty body:

final MyClass result = ClientBuilder.newClient()
    .target("http://localhost:8080")
    .path("path")
    .queryParam("key", "value")
    .request(APPLICATION_JSON)
    .post(Entity.json(null), MyClass.class)

Boroughenglish

I tried that but got a MessageBodyProviderNotFoundException: MessageBodyWriter not found for media type=application/json,...? – Nozzle

Well that's an entirely different problem... you should either register the default JacksonFeature, or write your own MessageBodyWriter/Reader – Boroughenglish

Ah I see you wrote that above, sorry. So null is the correct answer, right? – Boroughenglish

Thats stupid. Should be an Enity.empty() static method – Abysm

The problem with this approach is that jersey will still set the content-type header according to the Entity-factory (in this case application/json). – Galbanum

This works but I believe it does not send a 'Content-Length: 0' header... some endpoints apparently require a Content-Length if you send a POST. Is there a way to add a header manually? – Outreach

You can add headers between the request and post calls if you need to: .request(APPLICATION_JSON).header(HttpHeaders.CONTENT_LENGTH, 0).post(Entity.json(null), MyClass.class) – Boroughenglish

As @Galbanum points out this will make a request with the Content-Type set to application/json which might not be what you want. If you want to POST an empty form, try post(Entity.form(new Form())) – Jessy

It doesn't work for me. Entity.json("") works fine. – Byrdie

Answer 2

I found that this worked for me:

Response r = client
    .target(url)
    .path(path)
    .queryParam(name, value)
    .request()
    .put(Entity.json(""));

Pass an empty string, not a null value.

Chalcography

Answer 3

I don't know if the version change it. But, the following doesn't work:

builder.put( Entity.json( null ) );

Where, the following works fine:

builder.put( Entity.json( "" ) );

Trenttrento

This worked for me. I was trying to unit test where the parameter value comes through as null. I tried the Entity.json("{}") answer suggested but that gave me a parameter with an instance with every field null rather than the parameter which is what I wanted. – Myrna

Answer 4

Just post an empty txt.

   .post(Entity.text(""));

Aden

Answer 5

It worked for me only with an empty json object string

.post(Entity.json("{}")

All other solutions, still produced 400 Bad Request

P.S. The request is done using MediaType.APPLICATION_JSON

Sensibility