12

I'm trying to make an asynchronous POST and DELETE which is form url encoded using Retrofit in Android 4.4

Here is my client - 

@FormUrlEncoded
@POST(INetwork.API_BASE_PREFIX + "/memberships.json")
void join(@Field("id") String id, Callback<?> cb);

@FormUrlEncoded
@DELETE(INetwork.API_BASE_PREFIX + "/memberships.json")
void leave(@Field("id") String id, Callback<?> cb);

And this is the exception - 

java.lang.IllegalArgumentException: IRepositoryClient.leave: FormUrlEncoded can only be specified on HTTP methods with request body (e.g., @POST).
        at retrofit.RestMethodInfo.methodError(RestMethodInfo.java:118)
        at retrofit.RestMethodInfo.parseMethodAnnotations(RestMethodInfo.java:191)
        at retrofit.RestMethodInfo.init(RestMethodInfo.java:128)
        at retrofit.RestAdapter$RestHandler.invokeRequest(RestAdapter.java:329)
        at retrofit.RestAdapter$RestHandler.access$100(RestAdapter.java:264)
        at retrofit.RestAdapter$RestHandler$2.obtainResponse(RestAdapter.java:315)
        at retrofit.CallbackRunnable.run(CallbackRunnable.java:42)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
        at retrofit.Platform$Android$2$1.run(Platform.java:142)
        at java.lang.Thread.run(Thread.java:841)

I looked through the source and it basically if the method doesn't have a body and the request is formurlencoded, this exception is thrown. Also I noticed that all example of FormUrlEncoded work fine when it is not asynchronous, i.e. I have a return type of some sort and no callback - sorry I'm a little lost

Should I send an empty body? Am I required to send one and won't the @Field parameters suffice?

Using Retrofit 1.5.0

rink.attendant.6
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Rickster
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    Is it not working without `@FormUrlEncoded`? That's a content encoding and delete seems to have no content. – zapl Mar 22 '14 at 02:33
  • 1. Can't use field parameters without encoding - If I do that there is an exception java.lang.IllegalArgumentException:@Field parameters can only be used with form encoding. (parameter #1). 2. Delete does have content, it has the Id – Rickster Mar 22 '14 at 06:15

2 Answers2

36

The RFC for HTTP is unclear on whether or not the DELETE method is allowed to have a request body or not. Retrofit is raising an error on the side of caution by not having one.

However, you can still include one (assuming the HTTP client supports it) by using a custom HTTP method annotation.

package com.myapp;

@Target(METHOD)
@Retention(RUNTIME)
@RestMethod(value = "DELETE", hasBody = true)
public @interface BODY_DELETE {
  String value();
}

Now specify your interface method using the custom annotation that you defined.

@FormUrlEncoded
@BODY_DELETE(INetwork.API_BASE_PREFIX + "/memberships.json")
void leave(@Field("id") String id, Callback<?> cb);
David Medenjak
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Jake Wharton
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23

Updated answer for Retrofit 2.0:

Retrofit 2 doesn't seem to have @RestMethod any more, so here is what works: 

@FormUrlEncoded
@HTTP(method = "DELETE", path = INetwork.API_BASE_PREFIX + "/memberships.json", hasBody = true)
void leave(@Field("id") String id, Callback<?> cb);

For retrofit 2.+

@FormUrlEncoded
@HTTP(method = "DELETE", path = INetwork.API_BASE_PREFIX + "/memberships.json", hasBody = true)
Callback<?> cb(@Field("id") String id);

and for RxRetrofit 2.+

@FormUrlEncoded
@HTTP(method = "DELETE", path = INetwork.API_BASE_PREFIX + "/memberships.json", hasBody = true)
Observable<?> cb(@Field("id") String id);
Amit Bhati
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radu122
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