graphql-guard

This tiny gem provides a field-level authorization for graphql-ruby.

Usage

Define a GraphQL schema:

# define type
PostType = GraphQL::ObjectType.define do
  name "Post"
  field :id, !types.ID
  field :title, !types.String
end

# define query
QueryType = GraphQL::ObjectType.define do
  name "Query"
  field :posts, !types[PostType] do
    argument :user_id, !types.ID
    resolve ->(_obj, args, _ctx) { Post.where(user_id: args[:user_id]) }
  end
end

# define schema
Schema = GraphQL::Schema.define do
  query QueryType
end

# execute query
GraphSchema.execute(
  query,
  variables: { user_id: 1 },
  context: { current_user: current_user }
)

Inline policies

Add GraphQL::Guard to your schema:

Schema = GraphQL::Schema.define do
  query QueryType
  use GraphQL::Guard.new # <======= ʘ‿ʘ
end

Now you can define guard for a field, which will check permissions before resolving the field:

QueryType = GraphQL::ObjectType.define do
  name "Query"
  field :posts, !types[PostType] do
    argument :user_id, !types.ID
    guard ->(_obj, args, ctx) { args[:user_id] == ctx[:current_user].id } # <======= ʘ‿ʘ
    ...
  end
end

You can also define guard, which will be executed for all fields in the type:

PostType = GraphQL::ObjectType.define do
  name "Post"
  guard ->(_post, ctx) { ctx[:current_user].admin? } # <======= ʘ‿ʘ
  ...
end

If guard block returns false, then it'll raise a GraphQL::Guard::NotAuthorizedError error.

Policy object

Alternatively, it's possible to describe all policies by using PORO (Plain Old Ruby Object), which should implement a guard method. For example:

class GraphqlPolicy
  RULES = {
    QueryType => {
      posts: ->(_obj, args, ctx) { args[:user_id] == ctx[:current_user].id }
    },
    PostType => {
      '*': ->(post, ctx) { ctx[:current_user].admin? }
    }
  }

  def self.guard(type, field)
    RULES.dig(type, field)
  end
end

Use pass this object to GraphQL::Guard:

Schema = GraphQL::Schema.define do
  query QueryType
  use GraphQL::Guard.new(policy_object: GraphqlPolicy) # <======= ʘ‿ʘ
end

Order of priority

GraphQL::Guard will use the policy in the following order of priority:

1. Inline policy on the field.
2. Policy from the policy object on the field.
3. Inline policy on the type.
4. Policy from the policy object on the type.

class GraphqlPolicy
  RULES = {
    PostType => {
      title: ->(_post, ctx) { ctx[:current_user].admin? },                                # <======= 2
      '*': ->(_post, ctx) { ctx[:current_user].admin? }                                   # <======= 4
    }
  }

  def self.guard(type, field)
    RULES.dig(type, field)
  end
end

PostType = GraphQL::ObjectType.define do
  name "Post"
  guard ->(_post, ctx) { ctx[:current_user].admin? }                                      # <======= 3
  field :title, !types.String, guard: ->(_post, _args, ctx) { ctx[:current_user].admin? } # <======= 1
end

Schema = GraphQL::Schema.define do
  query QueryType
  use GraphQL::Guard.new(policy_object: GraphqlPolicy)
end

Installation

Add this line to your application's Gemfile:

gem 'graphql-guard'

And then execute:

$ bundle

Or install it yourself as:

$ gem install graphql-guard

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/exAspArk/graphql-guard. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

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

Code of Conduct

Everyone interacting in the Graphql::Guard project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.