praxis-mapper + activesupport 4.x do not play well together with Time

[stevecrozz]

Praxis mapper defines data accessors that freeze underlying data objects:
https://github.com/praxis/praxis-mapper/blob/c391302b8ed7637fa40af9492868d19b913b81d3/lib/praxis-mapper/model.rb

But activesupport 4.x foolishly defines a to_time method that mutates Time objects:
https://github.com/rails/rails/blob/v4.2.8/activesupport/lib/active_support/core_ext/date_and_time/compatibility.rb#L19-L25

This effectively prevents us from rendering models that have times and in our application logs we get:

2017-03-10 10:08:39 -0800: [] [ERROR] [WORKER] SAVE_TO_CACHE (failed) Account: 7954, Error: Attributor::DumpError: Error while dumping attribute last_volume_attachment of type V2::MediaTypes::Volume for context volume-F69NQB79UM6HV. Reason: can't modify frozen Time, Cause: can't modify frozen Time
2017-03-10 10:08:39 -0800: [] [ERROR] [WORKER] SAVE_TO_CACHE (failed) Backtrace:
/home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/renderer.rb:79:in `rescue in block (2 levels) in _render'
/home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/renderer.rb:76:in `block (2 levels) in _render'
/home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/renderer.rb:75:in `each'
/home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/renderer.rb:75:in `each_with_object'
/home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/renderer.rb:75:in `block in _render'
/home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-4.2.8/lib/active_support/notifications.rb:166:in `instrument'
/home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/renderer.rb:74:in `_render'
/home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/renderer.rb:50:in `render'
/home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/view.rb:35:in `render'
/home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/blueprint.rb:307:in `render'
/home/stevecrozz/Projects/rs/account_overview/app/v2/modules/big_brother_stat_calculator.rb:550:in `rescue in block in render_resources'
...

I dug into this for a while and ended up upgrading to activesupport 5.x which doesn't have this problem. I'm not sure on the right fix or even if praxis-mapper has a problem. IMO this is more of an activesupport 4.x problem, but since that's such a popular library and already superceded by 5.x, it seems unlikely that it can be fixed in activesupport.

[careo]

Yeah. I hit something like this too and was confused why it was frozen myself. I'm sure we had a reason for freezing it, but I've no idea what that was.

…

On Mar 10, 2017, at 10:22 AM, Stephen Crosby ***@***.***> wrote: Praxis mapper defines data accessors that freeze underlying data objects: https://github.com/praxis/praxis-mapper/blob/c391302b8ed7637fa40af9492868d19b913b81d3/lib/praxis-mapper/model.rb But activesupport 4.x foolishly defines a to_time method that mutates Time objects: https://github.com/rails/rails/blob/v4.2.8/activesupport/lib/active_support/core_ext/date_and_time/compatibility.rb#L19-L25 This effectively prevents us from rendering models that have times and in our application logs we get: 2017-03-10 10:08:39 -0800: [] [ERROR] [WORKER] SAVE_TO_CACHE (failed) Account: 7954, Error: Attributor::DumpError: Error while dumping attribute last_volume_attachment of type V2::MediaTypes::Volume for context volume-F69NQB79UM6HV. Reason: can't modify frozen Time, Cause: can't modify frozen Time 2017-03-10 10:08:39 -0800: [] [ERROR] [WORKER] SAVE_TO_CACHE (failed) Backtrace: /home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/renderer.rb:79:in `rescue in block (2 levels) in _render' /home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/renderer.rb:76:in `block (2 levels) in _render' /home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/renderer.rb:75:in `each' /home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/renderer.rb:75:in `each_with_object' /home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/renderer.rb:75:in `block in _render' /home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-4.2.8/lib/active_support/notifications.rb:166:in `instrument' /home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/renderer.rb:74:in `_render' /home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/renderer.rb:50:in `render' /home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/view.rb:35:in `render' /home/stevecrozz/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/praxis-blueprints-3.3/lib/praxis-blueprints/blueprint.rb:307:in `render' /home/stevecrozz/Projects/rs/account_overview/app/v2/modules/big_brother_stat_calculator.rb:550:in `rescue in block in render_resources' ... I dug into this for a while and ended up upgrading to activesupport 5.x which doesn't have this problem. I'm not sure on the right fix or even if praxis-mapper has a problem. IMO this is more of an activesupport 4.x problem, but since that's such a popular library and already superceded by 5.x, it seems unlikely that it can be fixed in activesupport. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or mute the thread.

[blanquer]

well...one reason is probably to respect the "not loaded" flagging:

praxis-mapper/lib/praxis-mapper/model.rb

Lines 232 to 235 in c391302

	def #{name}
	@__#{name} ||= @data.fetch(#{name.inspect}) do
	raise "field #{name.inspect} not loaded for #{self.inspect}."
	end.freeze

... as if the accessor is modified, then our code catching that will go away.

If necessary (and I agree that "might" not be at this point) we could make the freezing optional. Even if it was triggered by a simple Constant ("ehem") variable so one could choose setting it to false, if it is absolutely necessary to use the 4.x series.