Oj.optimize_rails breaks JSON.load - creates BigDecimal instead of Float

[seandilda]

I ran into an issue in my application after adding the oj gem. I tracked it down to oj turning some numeric values into BigDecimal objects when parsing them. Without oj, they are read as a Float object.

Loading development environment (Rails 6.1.7.6)
irb> JSON.load('{"key":175620.54484250804}')['key'].class
=> Float
irb> Oj.optimize_rails
=> nil
irb> JSON.load('{"key":175620.54484250804}')['key'].class
=> BigDecimal
irb>

Rails version: 6.1.7.6
Ruby version: 3.0

The particular issue I'm seeing happens when using JSON as the encoder for ActiveRecord::Store: https://api.rubyonrails.org/v6.1/classes/ActiveRecord/Store.html

[ohler55]

It sounds like the :bigdecimal_load option is not set to :float. It gets a bit tricky with a mixture of rails and json. The calls that start with JSON. are from the json gem yet rails changes some of the defaults and setting of the json gem. Can you try setting :bigdecimal_load before calling JSON.load and see if that makes a difference?

[seandilda]

Thank you. Running Oj.default_options = { bigdecimal_load: :float } did fix the issue.

Is this something that should be done automatically by Oj.optimize_rails ?
If there's a concern of breaking compatibility with existing deployments, could the rails page recommend setting this option?

[ohler55]

There might be. I'll dig into it a bit more tonight. I'm not sure what the default is for rails and json. Does your environment change any defaults that might effect the processing and if so that would they be called?