Errors encoding protocol buffers

[gogogarrett]

I'm having difficulties trying to encode protocol buffer messages.

Given the follow protobuf definition

enum AllowedProducts {
  maths = 1;
  reading = 2; 
}
enum AllowedPrecincts {
  my_lessons = 1;
  driving_tests = 2;
}
message X_CompleteActivity {
  required AllowedProducts product = 1; 
  required AllowedPrecincts precinct = 2;
  required AllowedEventTypes event_type = 3 [default = CompleteActivity];
  required int32 canonical_student_id = 4;
  optional int32 lesson = 5;
  optional int32 activity = 6;
  optional string created_at = 7;
}

We can see that encoding some things works, while others do not.

# all ok
iex(17)> ExProtobufs.encode(:complete_activity, [lesson: 1, activity: 1, canonical_student_id: 1, product: :rejr, precinct: :peek_a_boo])
{:ok, <<8, 5, 16, 6, 24, 2, 32, 1, 40, 1, 48, 1>>}

iex(18)> Poison.encode(<<8, 5, 16, 6, 24, 2, 32, 1, 40, 1, 48, 1>>)
{:ok, "\"\\b\\u0005\\u0010\\u0006\\u0018\\u0002 \\u0001(\\u00010\\u0001\""}

# things break
iex(19)> ExProtobufs.encode(:complete_activity, [lesson: 130, activity: 1, canonical_student_id: 1, product: :rejr, precinct: :peek_a_boo])
{:ok, <<8, 5, 16, 6, 24, 2, 32, 1, 40, 130, 1, 48, 1>>}
iex(20)> Poison.encode(<<8, 5, 16, 6, 24, 2, 32, 1, 40, 130, 1, 48, 1>>)
** (FunctionClauseError) no function clause matching in Poison.Encoder.BitString.chunk_size/3
    (poison) lib/poison/encoder.ex:127: Poison.Encoder.BitString.chunk_size(<<130, 1, 48, 1>>, nil, 1)
    (poison) lib/poison/encoder.ex:122: Poison.Encoder.BitString.escape/2
    (poison) lib/poison/encoder.ex:97: Poison.Encoder.BitString.escape/2
    (poison) lib/poison/encoder.ex:124: Poison.Encoder.BitString.escape/2
    (poison) lib/poison/encoder.ex:97: Poison.Encoder.BitString.escape/2
    (poison) lib/poison/encoder.ex:91: Poison.Encoder.BitString.escape/2
    (poison) lib/poison/encoder.ex:84: Poison.Encoder.BitString.encode/2
    (poison) lib/poison.ex:41: Poison.encode!/2
    (poison) lib/poison.ex:15: Poison.encode/2

Do you have any additional information as to why this might be? If I'm trying to do something that isn't intended?

[ericmj]

JSON does not support encoding binary data, it can encode UTF8 strings so you can Base64 encode your binary data before calling Poison.encode or you can use a binary encoding format instead of JSON.

[devinus]

Correct. Also, Poison 4.0 will throw a standardized EncodeError and explain why when this happens in the future.

[gogogarrett]

Great, thanks for the information!