How to handle null param values in Retrofit

问题

We're moving from Apache's http client to Retrofit and we've found some edge cases where param values can be null.

Apache used to intercept these and turn them into empty strings, but Retrofit throws an IllegalArgumentException.

We want to replicate the old behavior so that it doesn't cause any unexpected issues out in production. Is there a way for me to swap these null values with empty strings before ParameterHandler throws an exception?

回答1:

You can try the following:

My web service (Asp.Net WebAPI):

[Route("api/values/getoptional")]
public IHttpActionResult GetOptional(string id = null)
{
    var response = new
    {
        Code = 200,
        Message = id != null ? id : "Response Message"
    };
    return Ok(response);
}

Android client:

public interface WebAPIService {
    ...

    @GET("/api/values/getoptional")
    Call<JsonObject> getOptional(@Query("id") String id);
}

MainActivity.java:

...
Call<JsonObject> jsonObjectCall1 = service.getOptional("240780"); // or service.getOptional(null);
jsonObjectCall1.enqueue(new Callback<JsonObject>() {
    @Override
    public void onResponse(Call<JsonObject> call, Response<JsonObject> response) {
        Log.i(LOG_TAG, response.body().toString());
    }

    @Override
    public void onFailure(Call<JsonObject> call, Throwable t) {
        Log.e(LOG_TAG, t.toString());
    }
});
...

Logcat output:

If using service.getOptional(null);

04-15 13:56:56.173 13484-13484/com.example.asyncretrofit I/AsyncRetrofit: {"Code":200,"Message":"Response Message"}

If using service.getOptional("240780");

04-15 13:57:56.378 13484-13484/com.example.asyncretrofit I/AsyncRetrofit: {"Code":200,"Message":"240780"}

来源：https://stackoverflow.com/questions/36634926/how-to-handle-null-param-values-in-retrofit

标签

android

retrofit

retrofit2