I would like to pull all attributes except for a few out of a model, and convert the data to json format.
A class I defined in my model:
mdl.rb
class Mdl< ActiveRecord::Base
def self.get_json
self.all.pluck(:a, :b, :c).to_json
end
end
This returns:
[[0.0,1.0,365.0]]
I have 2 questions:
1) How can I have the json return with attribute names? i.e. [a: 0.0, b: 1.0, c: 365.0]
2) Is there a way to pull the attributes based on 'all columns except x, y, & z'?
1) Instead of doing a self.all.pluck, try
self.all.to_json or
self.all.as_json
this will give you the attribute names like you wanted.
2) You can use select, for example:
self.all.select(:a, :b, :c)
That should work
Common approach currently is to use ActiveModelSerializers gem for that. It'll allow you to manage your json serialization same way as you manage your views. So first serializer using that will be like this:
class MdlSerializer < ActiveModel::Serializer
attributes :a, :b, :c
end
and you will be able to render it to json with automatic serializer lookup like this:
render json: @mdl
ActiveModelSerializers is de-facto standard for Rails 5, and works well in Rails 4.
