Can't correctly convert GPB to JSON

[Florian Simond]

I'm trying to convert a gpb to JSON, but I can't get a satisfactory result.

I am quite new to GPB and ScalaPB, and therefore not sure if this is a bug or not

How to reproduce the problem:

Proto file:

syntax = "proto3";

package test;


message Dictionary {
    repeated Pair pairs = 1;
}


message Pair {
    string key = 1;
    oneof value_by_type {
        string string_value = 2;
        uint32 uint32_value = 3;
    }
}

val dict = Dictionary(Seq(Pair("myKey", Uint32Value(0))))
println(dict)
val dictBytes = dict.toByteArray
val dictP = Dictionary.parseFrom(dictBytes)
println(dictP)
val jObj = new scalapb.json4s.Printer(
    includingDefaultValueFields = true,
    preservingProtoFieldNames = true
).print(dictP)
println(jObj)

output:

Dictionary(List(Pair(keykey,Uint32Value(0))))
Dictionary(Vector(Pair(keykey,Uint32Value(0))))
{"pairs":[{"key":"keykey","string_value":"","uint32_value":0}]}

If I set includingDefaultValueFields to false, I get: 

{"pairs":[{"key":"keykey"}]}

I understand that 0 is the default value and that's why the field is removed, but is there a way to say that we want to keep all the fields that were actually used ?

The printing of dictP seems quite good:

Dictionary(Vector(Pair(keykey,Uint32Value(0)))), and that's what I would like to get as a JSON... :

{"pairs":[{"key":"keykey","uint32_value":0}]}

Is there a way to do that ?

[Nadav Samet]

Hi Florian,

I think that the problem you are describing has been fixed in scalapb-json4s 0.7.1. Which version are you using?

-Nadav

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-Nadav

[Nadav Samet]

FWIW, I added a unit test which seems to confirm that the current version should work as you'd expect; https://github.com/scalapb/scalapb-json4s/commit/7f233c61b1e6f0171febc2886af9cce5c1b184c3

--

-Nadav

[Florian Simond]

Hi Nadav,

Thanks so much for your help. Indeed, I was using version 0.7.0, I did not realise that 0.7.1 was out. It now works as expected :)

I have another question, Is there an "easy" way to change the way a generated object is converted to json ? For example, is there a way to force a Pair object to be converted to {key.value: ValueByType.value} instead of {"key": key.value, "ValueByType": ValueByType.value}

{"key":"keykey","uint32_value":0}

should be

{"keykey":0}

I have been able to do that with spray-json, but not with scalapb-json4s at the moment...

Thanks again,

Florian

[Nadav Samet]

Yes, take a look at FormatRegistry - it lets you customize the way a message get serialized, and you can accomplish the effect that you want by customizing how Pair is serialized.

Hope this helps,

Nadav

On Thu, May 24, 2018 at 11:25 PM, Florian Simond <fsim...@gmail.com> wrote:

Hi Nadav,

Thanks so much for your help. Indeed, I was using version 0.7.0, I did not realise that 0.7.1 was out. It now works as expected :)

I have another question, Is there an "easy" way to change the way a generated object is converted to json ? For example, is there a way to force a Pair object to be converted to {key.value: ValueByType.value} instead of {"key": key.value, "ValueByType": ValueByType.value}

{"key":"keykey","uint32_value":0}

should be

{"keykey":0}

I have been able to do that with spray-json, but not with scalapb-json4s at the moment...

Thanks again,

Florian

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-Nadav