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Action Policy GraphQL

This gem provides an integration for using Action Policy as an authorization framework for GraphQL applications (built with graphql ruby gem).

This integration includes the following features:

Fields & mutations authorization
List and connections scoping
Exposing permissions/authorization rules in the API.

📑 Documentation

Installation

Add this line to your application's Gemfile:

gem "action_policy-graphql"

Usage

NOTE: this is a quick overview of the functionality provided by the gem. For more information see the documentation.

To start using Action Policy in GraphQL-related code, you need to enhance your base classes with ActionPolicy::GraphQL::Behaviour:

# For fields authorization, lists scoping and rules exposing
class Types::BaseObject < GraphQL::Schema::Object
  include ActionPolicy::GraphQL::Behaviour
end

# For using authorization helpers in mutations
class Types::BaseMutation < GraphQL::Schema::Mutation
  include ActionPolicy::GraphQL::Behaviour
end

# For using authorization helpers in resolvers
class Types::BaseResolver < GraphQL::Schema::Resolver
  include ActionPolicy::GraphQL::Behaviour
end

`authorize: *`

You can add authorization to the fields by specifying the authorize: * option:

field :home, Home, null: false, authorize: true do
  argument :id, ID, required: true
end

# field resolver method
def home(id:)
  Home.find(id)
end

The code above is equal to:

field :home, Home, null: false do
  argument :id, ID, required: true
end

def home(id:)
  Home.find(id).tap { |home| authorize! home, to: :show? }
end

You can customize the authorization options, e.g. authorize: {to: :preview?, with: CustomPolicy}.

If you don't want to raise an exception but return a null instead, you should set a raise: false option.

Note: it does not make too much sense to use authorize in mutations since it's checking authorization rules after mutation is executed. Therefore authorize marked as deprecated when used in mutations and will raise error in future releases.

`authorized_scope: *`

You can add authorized_scope: true option to the field (list or connection field) to apply the corresponding policy rules to the data:

class CityType < ::Common::Graphql::Type
  # It would automatically apply the relation scope from the EventPolicy to
  # the relation (city.events)
  field :events, EventType.connection_type, null: false, authorized_scope: true

  # you can specify the policy explicitly
  field :events, EventType.connection_type, null: false, authorized_scope: {with: CustomEventPolicy}
end

NOTE: you cannot use authorize: * and authorized_scope: * at the same time but you can combine preauthorize: * or authorize_field: * with authorized_scope: *.

`preauthorize: *`

If you want to perform authorization before resolving the field value, you can use preauthorize: * option:

field :homes, [Home], null: false, preauthorize: {with: HomePolicy}

def homes
  Home.all
end

The code above is equal to:

field :homes, [Home], null: false

def homes
  authorize! "homes", to: :index?, with: HomePolicy
  Home.all
end

NOTE: we pass the field's name as the record to the policy rule. We assume that preauthorization rules do not depend on the record itself and pass the field's name for debugging purposes only.

You can customize the authorization options, e.g. preauthorize: {to: :preview?, with: CustomPolicy}.

NOTE: unlike authorize: * you MUST specify the with: SomePolicy option. The default authorization rule depends on the type of the field:

for lists we use index? (configured by ActionPolicy::GraphQL.default_preauthorize_list_rule parameter)
for singleton fields we use show? (configured by ActionPolicy::GraphQL.default_preauthorize_node_rule parameter)

`authorize_field: *`

If you want to perform authorization before resolving the field value on the base of the upper object, you can use authorize_field: * option:

field :homes, Home, null: false, authorize_field: true

def homes
  Home.all
end

The code above is equal to:

field :homes, [Home], null: false

def homes
  authorize! object, to: :homes?
  Home.all
end

By default we use #{underscored_field_name}? authorization rule.

You can customize the authorization options, e.g. authorize_field: {to: :preview?, with: CustomPolicy}.

`expose_authorization_rules`

You can add permissions/authorization exposing fields to "tell" clients which actions could be performed against the object or not (and why).

For example:

class ProfileType < ::Common::Graphql::Type
  # Adds can_edit, can_destroy fields with
  # AuthorizationResult type.

  # NOTE: prefix "can_" is used by default, no need to specify it explicitly
  expose_authorization_rules :edit?, :destroy?, prefix: "can_"
end

Then the client could perform the following query:

{
  post(id: $id) {
    canEdit {
      # (bool) true|false; not null
      value
      # top-level decline message ("Not authorized" by default); null if value is true
      message
      # detailed information about the decline reasons; null if value is true
      reasons {
        details # JSON-encoded hash of the failure reasons (e.g., {"event" => [:seats_available?]})
        fullMessages # Array of human-readable reasons (e.g., ["This event is sold out"])
      }
    }

    canDestroy {
      # ...
    }
  }
}

You can specify a custom field name as well (only for a single rule):

class ProfileType < ::Common::Graphql::Type
  # Adds can_create_post field.

  expose_authorization_rules :create?, with: PostPolicy, field_name: "can_create_post"
end

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/palkan/action_policy-graphql.

License

The gem is available as open source under the terms of the MIT License.