Fixed issue with ActiveRecord serialize object as JSON

[jenncoop]

With 4.1.x serialize started returning a string when JSON was passed as the second attribute. It will now return a hash as per previous versions (prior to 4.1.x)

Example: An ActiveRecord model named Post with a comment column that uses the serialize method to convert a Comment object to JSON.

class Post < ActiveRecord::Base
serialize :comment, JSON
end

class Comment
  include ActiveModel::Model
  attr_accessor :category, :text
end

post = Post.create!
post.comment = Comment.new(category: "Animals", text: "This is a comment about squirrels.")
post.save!

# This will now return a hash
post.comment

When JSON is used with serialize, ActiveRecord will use the new ActiveRecord::Coders::JSON coder which delegates ActiveRecord::Coders::JSON.dump/load to ActiveSupport::JSON.encode/decode.

Fixes #15594

[chancancode]

@jeremy @matthewd can one of you take a second look at this to see if it matches what you have in mind? If it seems fine with you we'll work on porting this to master.

[sgrif]

👍 from me on this.

[matthewd]

Even though it's not needed ::JSON may be nice here, to be very clear?

I think this probably also deserves a comment noting that we're consciously actually breaking our contract (by ignoring the #dump/#load present on the supplied object) to maintain better compatibility with 4.0.

[egilburg]

Would anyone conceivably want to actually use the native ::JSON serializer which this implementation will suppress?

An alternate (not sure if good/even possible idea but just throwing out there) is to alias within ActiveRecord::Base namespace (or ActiveRecord in general, or Rails even more general) JSON to ActiveSupport::JSON, making users always use ::JSON if they want the native serializer.

[matthewd]

👍