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jsonrubysequel

How to serialize a Sequel result into JSON

This is my Model

class Client < Sequel::Model(:clients)
end

When I execute 

Client.first.to_json

I get 

"\"#<Client:0x2594b824>\""

But when I execute 

DB[:clients].first.to_json

I correctly get:

{id: 1, name: "Someone" ... }

What am I doing wrong?... I also tried using Client.dataset.first.json having the same result.

Also I'm using a MS Access DB but I don't think that's important.

Solution

  • The json library (part of the Ruby standard library), and other gems such as ActiveSupport, monkey patch objects with a to_json method which could be what is getting called, not a the specific to_json method supplied by Sequel which knows how to convert a Sequel::Model instance to JSON. This is speculation as I'd be surprised that the JSON library monkey patches anything other than String, Array, Hash etc.

    When using DB[:clients].first you probably get back a Hash which has a to_json method, where as Client.first returns a model instance which isn't handled by the generic to_json method supplied by the json library.

    Try registering the Sequel JSON plugin, this should take precedence over the monkey patched to_json method:

    Sequel::Model.plugin :json_serializer

    By the way this is a good indicator of why monkey patching is often a bad idea, particularly monkey patching of classes which are outside a libraries/gems namespace.