[larouxn]

To ensure we don't encounter representable gem based MultiJson deprecation warnings I am proposing we raise the representable gem version requirement from '~> 3.0' to '~> 3.3', '>= 3.3.1' and multi_json gem version requirement from '~> 1.11' to '~> 1.21', '>= 1.21.2'.

Relevant links

• https://github.com/trailblazer/representable/blob/a0612bf545f742fe3f3be9d554cbae18bea10b75/CHANGES.md#330
• https://github.com/sferik/multi_json/blob/c44e92e886e6479f60ff1769e06db7eb01c0abf2/CHANGELOG.md#1210
• Crash on load: multi_json is not part of the bundle. Add it to your Gemfile. #26611 (comment)

[seuros]

bump multi_json to '~> 1.21'

[torreypayne]

@larouxn LGTM to bump the dependencies for maintenance, but are you sure this update actually clears the warnings? Can you repro?

[larouxn]

@larouxn LGTM to bump the dependencies for maintenance, but are you sure this update actually clears the warnings? Can you repro?

Thanks for the review! Good call. Unfortunately I believe that due to this (temporary I hope) compatibility fix some deprecation warnings will still appear. I suppose until representable drops that we will continue to see some deprecation warnings, despite representable v3.3.0 specifically noting it will: "Fix deprecations with MultiJson.".

https://github.com/trailblazer/representable/blob/a0612bf545f742fe3f3be9d554cbae18bea10b75/lib/representable/json.rb#L9-L18

Reproduction Test (disclaimer: LLM assisted)

Running this script with representable 3.2.0 vs 3.3.0 demonstrates the behaviour:

# test_repro.rb
require "multi_json"       # 1.21.1
require "representable/json"

class Model
  attr_accessor :name
  def initialize(name = nil); @name = name; end
end

module ModelRepresenter
  include Representable::JSON
  property :name
end

m = Model.new("Alice")
m.extend(ModelRepresenter).to_json
Model.new.extend(ModelRepresenter).from_json('{"name":"Bob"}')

Result with representable 3.2.0 (ruby -W:deprecated test_repro.rb):

The MultiJson constant is deprecated and will be removed in v2.0. Use MultiJSON instead.
MultiJSON.dump is deprecated and will be removed in v2.0. Use MultiJSON.generate instead.
MultiJSON.load is deprecated and will be removed in v2.0. Use MultiJSON.parse instead.

Result with representable 3.3.0 (ruby -W:deprecated test_repro.rb):

The MultiJson constant is deprecated and will be removed in v2.0. Use MultiJSON instead.
MultiJSON.dump is deprecated and will be removed in v2.0. Use MultiJSON.generate instead.
MultiJSON.load is deprecated and will be removed in v2.0. Use MultiJSON.parse instead.

Note: If we remove Representable::JSON::MultiJSON from representable so it actually delegates to top-level ::MultiJSON, all warnings should disappear completely.

[larouxn]

Rebased on latest main to pick up potential fixes from #28043.

[quartzmo]

Could this be '~> 3.3', '>= 3.3.1'?

With multi_json 1.21, representable 3.3.0 still sends to_json/from_json through the deprecated MultiJson.dump/load, which matches your repro showing the same warnings on 3.2.0 and 3.3.0.

3.3.1 (trailblazer/representable#300) fixes this, and for me the warnings go away with it:

ruby -W:deprecated test_repro.rb
# representable 3.3.0 + multi_json 1.21.1: 3 deprecation warnings
# representable 3.3.1 + multi_json 1.21.1: none

[quartzmo]

Could this be '~> 1.21', '>= 1.21.2'?

multi_json 1.21.2 added json 3.x support (https://github.com/sferik/multi_json/blob/main/CHANGELOG.md#1212---2026-09-07), and older versions raise ArgumentError: wrong number of arguments (given 2, expected 1) on every to_json/from_json when json 3.x is in the bundle. With representable 3.3.1 and json 3.1.0, the google-apis-core specs give:

multi_json 1.21.1: 524 examples, 44 failures (all ArgumentError)
multi_json 1.21.2: 524 examples, 0 failures

One bundle lock --update multi_json representable --conservative would pick up both bumps in Gemfile.lock. With both changes merged onto current main, the specs pass on Ruby 3.2 through 4.0.

[quartzmo]

Thanks for your patience with this review, and sorry for the delays. If you don't have time for these two tweaks, no problem: I'm happy to push them to your branch in a couple of days so we can get this merged.

[larouxn]

👋 @quartzmo, thanks a bunch for the review and good call on setting the minimum allowed versions in the Gemspec for multi_json and representable. I have made both changes and rebased on latest main.