No validation error if invalid JSON string is passed and schema allows empty object (no presence validation)

[alexander-e1off]

Env: ruby 2.7.1, Rails 6.0.3.2
Modified given example as follows:
Schema (added empty object):

{
  "$schema": "http://json-schema.org/draft-04/schema",
  "oneOf": [
    { "$ref": "#/definitions/profile" },
    { "$ref": "#/definitions/empty" }
  ],
  "definitions": {
  "profile": {
    "type": "object",
    "properties": {
      "city": { "type": "string" },
      "country": { "type": "string" }
    },
    "required": ["country"]
  },
  "empty": {
    "type": "object",
    "properties": {},
    "additionalProperties": false
  }
}

Model (removed 'profile' presence validation):

create_table "users" do |t|
  t.string "name"
  t.json "profile" # First-class JSON with PostgreSQL, yo.
end

class User < ActiveRecord::Base
  # Constants
  PROFILE_JSON_SCHEMA = Rails.root.join('config', 'schemas', 'profile.json_schema').to_s

  # Validations
  validates :name, presence: true
  validates :profile, json: { schema: PROFILE_JSON_SCHEMA }
end

Expected result:

user = User.new(name: 'Samuel Garneau', profile: '{invalid JSON":}')
user.valid? # => false
user.profile_invalid_json # => '{invalid JSON":}'

Observed result:

user = User.new(name: 'Samuel Garneau', profile: '{invalid JSON":}')
user.valid? # => true
user.profile_invalid_json # => '{invalid JSON":}'

Since attribute setter got JSON parsing error, it replaces it with empty object {} which is passed then to validate_each, and if schema supports empty object, validation is passed and no error is added even if "#{attribute}_invalid_json" is not empty.

It seems it is needed to add in the beginning of validate_each method something like:

return record.errors.add(attribute, 'JSON parse error') if record.send(:"#{attribute}_invalid_json").present?

[remi]

Hi Alexander,

Very sorry about the delayed response. Can you tell me if the issue is still present in 2.0+, now that the json_schemer gem is used?

And if so, would you mind sending a pull request with your proposed changes?

Thank you! ✌️