JSI filter serialized ActiveRecord

jsi_filter_serialized_activerecord.rb

require 'jsi'

# db/model setup

require 'active_record'
dbpath = Pathname.new("tmp.sqlite3")
dbpath.unlink if dbpath.exist?
at_exit { dbpath.unlink }
ActiveRecord::Base.establish_connection(
  :adapter => "sqlite3",
  :database  => dbpath
)

ActiveRecord::Schema.define do
  create_table :users do |table|
    table.column :name, :string
    table.column :email, :string
    table.column :age, :integer
    table.column :secret, :string
  end
end

class User < ActiveRecord::Base
end

# record → JSON

user = User.create!(
  name: 'Me',
  email: 'me@here',
  age: 0,
  secret: '🤐',
)
user_json = user.serializable_hash # using ActiveRecord's builtin serialization
puts "json"
pp user_json
# → {"id" => 1, "name" => "Me", "email" => "me@here", "age" => 0, "secret" => "🤐"}


# Filtering by _described_ attributes

user_schema = JSI.new_schema({
  "$schema" => "http://json-schema.org/draft-07/schema",
  "type" => "object",
  "properties" => {
    "id" => {},
    "name" => {"type" => "string"},
    # ❌ no "email"
    "age" => {"type" => "integer", "minimum" => 1},
    # ❌ no "secret"
  },
})
user_jsi = user_schema.new_jsi(user_json)

user_filtered = user_jsi.jsi_select_descendents_leaf_first do |node|
  # reject nodes which have no schemas that describe them
  !node.jsi_schemas.empty?
end
puts "filter described attributes: no email, no secret"
pp user_filtered
# → #{<JSI> "id" => 1, "name" => "Me", "age" => 0}


# Filtering by _excluded_ attributes with `false` schema

user_schema = JSI.new_schema({
  "$schema" => "http://json-schema.org/draft-07/schema",
  "type" => "object",
  "properties" => {
    "id" => {},
    "name" => {"type" => "string"},
    # ✅ "email" is not specifically excluded
    "age" => {"type" => "integer", "minimum" => 1},
    "secret" => false, # ❌ will exclude "secret"
  },
})
user_jsi = user_schema.new_jsi(user_json)

user_filtered = user_jsi.jsi_select_descendents_leaf_first do |node|
  # reject nodes described by `false` schema
  !node.jsi_schemas.any? { |s| s.schema_content == false }
end
puts "filter excluded attributes: no secret"
pp user_filtered
# → #{<JSI> "id" => 1, "name" => "Me", "email" => "me@here", "age" => 0}


# Filtering by _valid_ attributes (this seems like a bad idea but worth illustrating)

user_schema = JSI.new_schema({
  "$schema" => "http://json-schema.org/draft-07/schema",
  "type" => "object",
  "properties" => {
    "id" => {},
    "name" => {"type" => "string"},
    # ✅ "email" has no schema, nothing makes it invalid
    "age" => {"type" => "integer", "minimum" => 1}, # ❌ age=0 fails validation
    "secret" => false, # ❌ nothing is valid against `false` schema
  },
})
user_jsi = user_schema.new_jsi(user_json)

user_filtered = user_jsi.jsi_select_descendents_leaf_first do |node|
  node.jsi_valid?
end
puts "filter valid attributes: no age, no secret"
pp user_filtered
# → #{<JSI> "id" => 1, "name" => "Me", "email" => "me@here"}