ActiveRecord::JSONValidator
makes it easy to validate
JSON attributes against a JSON schema.
Add this line to your application's Gemfile:
gem 'activerecord_json_validator', '~> 3.0.0'
Schemas should be a JSON file
{
"type": "object",
"$schema": "http://json-schema.org/draft-04/schema#",
"properties": {
"city": { "type": "string" },
"country": { "type": "string" }
},
"required": ["country"]
}
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')
# Validations
validates :name, presence: true
validates :profile, presence: true, json: { schema: PROFILE_JSON_SCHEMA }
end
user = User.new(name: 'Samuel Garneau', profile: { city: 'Quebec City' })
user.valid? # => false
user = User.new(name: 'Samuel Garneau', profile: { city: 'Quebec City', country: 'Canada' })
user.valid? # => true
user = User.new(name: 'Samuel Garneau', profile: '{invalid JSON":}')
user.valid? # => false
user.profile_invalid_json # => '{invalid JSON":}'
Option | Description |
---|---|
:schema |
The JSON schema to validate the data against (see Schema section) |
:value |
The actual value to use when validating (see Value section) |
:message |
The ActiveRecord message added to the record errors (see Message section) |
:options |
A Hash of json_schemer -supported options to pass to the validator |
ActiveRecord::JSONValidator
uses the json_schemer gem to validate the JSON
data against a JSON schema.
Additionally, you can use a Symbol
or a Proc
. Both will be executed in the
context of the validated record (Symbol
will be sent as a method and the
Proc
will be instance_exec
ed)
class User < ActiveRecord::Base
# Constants
PROFILE_REGULAR_JSON_SCHEMA = Rails.root.join('config', 'schemas', 'profile.json_schema')
PROFILE_ADMIN_JSON_SCHEMA = Rails.root.join('config', 'schemas', 'profile_admin.json_schema')
# Validations
validates :profile, presence: true, json: { schema: lambda { dynamic_profile_schema } } # `schema: :dynamic_profile_schema` would also work
def dynamic_profile_schema
admin? ? PROFILE_ADMIN_JSON_SCHEMA : PROFILE_REGULAR_JSON_SCHEMA
end
end
The schema is passed to the JSONSchemer.schema
function, so it can be anything supported by it:
class User < ActiveRecord::Base
# Constants
JSON_SCHEMA = Rails.root.join('config', 'schemas', 'profile.json_schema')
# JSON_SCHEMA = { 'type' => 'object', 'properties' => { 'foo' => { 'type' => 'integer', 'minimum' => 3 } } }
# JSON_SCHEMA = '{"type":"object","properties":{"foo":{"type":"integer","minimum":3}}}'
# Validations
validates :profile, presence: true, json: { schema: JSON_SCHEMA }
end
By default, the validator will use the โgetterโ method to the fetch attribute value and validate the schema against it.
# Will validate `self.foo`
validates :foo, json: { schema: SCHEMA }
But you can change this behavior if the getter method doesnโt return raw JSON data (a Hash
):
# Will validate `self[:foo]`
validates :foo, json: { schema: SCHEMA, value: ->(record, _, _) { record[:foo] } }
You could also implement a โraw getterโ if you want to avoid the value
option:
# Will validate `self[:foo]`
validates :raw_foo, json: { schema: SCHEMA }
def raw_foo
self[:foo]
end
Like any other ActiveModel validation, you can specify either a Symbol
or
String
value for the :message
option. The default value is :invalid_json
.
However, you can also specify a Proc
that returns an array of errors. The
Proc
will be called with a single argument โ an array of errors returned by
the JSON schema validator. So, if youโd like to add each of these errors as
a first-level error for the record, you can do this:
class User < ActiveRecord::Base
# Validations
validates :profile, presence: true, json: { message: ->(errors) { errors }, schema: 'foo.json_schema' }
end
user = User.new.tap(&:valid?)
user.errors.full_messages
# => [
# 'The property '#/email' of type Fixnum did not match the following type: string in schema 2d44293f-cd9d-5dca-8a6a-fb9db1de722b#',
# 'The property '#/full_name' of type Fixnum did not match the following type: string in schema 2d44293f-cd9d-5dca-8a6a-fb9db1de722b#',
# ]
The tests require a database. We've provided a simple docker-compose.yml
that will make
it trivial to run the tests against PostgreSQL. Simply run docker compose up -d
followed by rake spec
. When you're done, run docker compose down
to stop the database.
In order to use another database, simply define the DATABASE_URL
environment variable
appropriately.
ActiveRecord::JSONValidator
is ยฉ 2013-2024 Mirego and may be freely distributed under the New BSD license. See the LICENSE.md
file.
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