Add an array as request parameter with Retrofit 2

Question

I\'m looking for way to add an int array (e.g [0,1,3,5]) as parameter in a GET request with retrofit 2. Then, the generated url should be like this : http:/

Answer 1

I have finally founded a solution by using Arrays.toString(int []) method and by removing spaces in this result because Arrays.toString return "[0, 1, 3, 5]". And my request method looks like this

@GET("http://server/service")
Observable<Void> getSomething(@Query("array") String array);

Answer 2

Just add it as a query param

@GET("http://server/service")
Observable<Void> getSomething(@Query("array") List<Integer> array);

You can also use int[], or Integer... as a last param;

Answer 3

Using toString didn't work for me. Instead, TextUtils.join(",", ids) does the trick.

Don't forget to mark the Query with encoded = true.

Answer 4

I faced a similar problem and had to do a couple of things to reach the acceptable form (as asked in the question).

1. Converted an ArrayList to String

   arrayList.toString().replace(" ", "")
   

2. In RetroFit method, I changed the Query param which accepts the ArrayList above to as follows:

   @Query(value = "cities", encoded = true)
   

This ensures that the brackets and commas are not URL encoded.

Answer 5

Use Iterable to encapsulate the integer list, or use a two-dimensional integer array.

• How to define:

  public interface ServerService {
      @GET("service")
      Call<Result> method1(@Query("array") Iterable<List<Integer>> array);
  
      @GET("service")
      Call<Result> method2(@Query("array") Integer[][] array);
  }
  

• How to use:

  Retrofit retrofit = new Retrofit.Builder()
      .baseUrl("http://server/")
      .addConverterFactory(GsonConverterFactory.create())
      .build();
  ServerService service = retrofit.create(ServerService.class);
  
  // Use the first method.
  List<Integer> data1 = Arrays.asList(0,1,3,5);
  Iterable array1 = Arrays.asList(data1);
  Call<Result> method1Call = service.method1(array1);
  
  // Use the second method.
  Integer[] data2 = new Integer[]{0,1,3,5};
  Integer[][] array2 = new Integer[][]{data2};
  Call<Result> method2Call = service.method2(array2);
  
  // Execute enqueue() or execute() of method1Call or method2Call.
  

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Please refer to the code ParameterHandler.java of Retrofit2 for the reason why the way can solve the problem.

Answer 6

You need to name your query param with an array syntax like so:

@GET("http://server/service")
Observable<Void> getSomething(@Query("array[]") List<Integer> array);

The syntax itself will vary by the backend technology being used, however not including the brackets "[]" will normally be interpreted as a single value.

For example, using array=1&array=2 will generally be interpreted by backends as only array=1 or array=2 instead of array=[1,2].