This gem provides a field-level authorization for graphql-ruby.
- Usage
- Priority order
- Integration
- Error handling
- Schema masking
- Installation
- Testing
- Development
- Contributing
- License
- Code of Conduct
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Define a GraphQL schema:
# Define a type
PostType = GraphQL::ObjectType.define do
name "Post"
field :id, !types.ID
field :title, types.String
end
# Define a 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 a schema
Schema = GraphQL::Schema.define do
query QueryType
end
# Execute query
Schema.execute(query, variables: { user_id: 1 }, context: { current_user: current_user })
Add GraphQL::Guard
to your schema:
Schema = GraphQL::Schema.define do query QueryType use GraphQL::Guard.new 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 } ... end end
You can also define guard
, which will be executed for every *
field in the type:
PostType = GraphQL::ObjectType.define do name "Post" guard ->(obj, args, ctx) { ctx[:current_user].admin? } ... end
If guard
block returns nil
or false
, then it'll raise a GraphQL::Guard::NotAuthorizedError
error.
Alternatively, it's possible to extract and 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 => { '*': ->(obj, args, ctx) { ctx[:current_user].admin? } } } def self.guard(type, field) RULES.dig(type, field) end end
Pass this object to GraphQL::Guard
:
Schema = GraphQL::Schema.define do query QueryType use GraphQL::Guard.new(policy_object: GraphqlPolicy) end
When using a policy object, you may want to allow introspection queries to skip authorization. A simple way to avoid having to whitelist every introspection type in the RULES
hash of your policy object is to check the type
parameter in the guard
method:
def self.guard(type, field) type.introspection? ? ->(_obj, _args, _ctx) { true } : RULES.dig(type, field) # or "false" to restrict an access end
GraphQL::Guard
will use the policy in the following order of priority:
- Inline policy on the field.
- Policy from the policy object on the field.
- Inline policy on the type.
- Policy from the policy object on the type.
class GraphqlPolicy RULES = { PostType => { '*': ->(obj, args, ctx) { ctx[:current_user].admin? }, # <=== 4 title: ->(obj, args, ctx) { ctx[:current_user].admin? } # <=== 2 } } def self.guard(type, field) RULES.dig(type, field) end end PostType = GraphQL::ObjectType.define do name "Post" guard ->(obj, args, ctx) { ctx[:current_user].admin? } # <=== 3 field :title, !types.String, guard: ->(obj, args, ctx) { ctx[:current_user].admin? } # <=== 1 end Schema = GraphQL::Schema.define do query QueryType use GraphQL::Guard.new(policy_object: GraphqlPolicy) end
You can simply reuse your existing policies if you really want. You don't need any monkey patches or magic for it ;)
# Define an ability class Ability include CanCan::Ability def initialize(user) user ||= User.new if user.admin? can :manage, :all else can :read, Post, author_id: user.id end end end # Use the ability in your guard PostType = GraphQL::ObjectType.define do name "Post" guard ->(post, args, ctx) { ctx[:current_ability].can?(:read, post) } ... end # Pass the ability Schema.execute(query, context: { current_ability: Ability.new(current_user) })
# Define a policy class PostPolicy < ApplicationPolicy def show? user.admin? || record.author_id == user.id end end # Use the ability in your guard PostType = GraphQL::ObjectType.define do name "Post" guard ->(post, args, ctx) { PostPolicy.new(ctx[:current_user], post).show? } ... end # Pass current_user Schema.execute(query, context: { current_user: current_user })
By default GraphQL::Guard
raises a GraphQL::Guard::NotAuthorizedError
exception if access to the field is not authorized.
You can change this behavior, by passing custom not_authorized
lambda. For example:
SchemaWithErrors = GraphQL::Schema.define do query QueryType use GraphQL::Guard.new( # By default it raises an error # not_authorized: ->(type, field) { raise GraphQL::Guard::NotAuthorizedError.new("#{type}.#{field}") } # Returns an error in the response not_authorized: ->(type, field) { GraphQL::ExecutionError.new("Not authorized to access #{type}.#{field}") } ) end
In this case executing a query will continue, but return nil
for not authorized field and also an array of errors
:
SchemaWithErrors.execute("query { posts(user_id: 1) { id title } }") # => { # "data" => nil, # "errors" => [{ # "messages" => "Not authorized to access Query.posts", # "locations": { "line" => 1, "column" => 9 }, # "path" => ["posts"] # }] # }
In more advanced cases, you may want not to return errors
only for some unauthorized fields. Simply return nil
if user is not authorized to access the field. You can achieve it, for example, by placing the logic into your PolicyObject
:
class GraphqlPolicy RULES = { PostType => { '*': { guard: ->(obj, args, ctx) { ... }, not_authorized: ->(type, field) { GraphQL::ExecutionError.new("Not authorized to access #{type}.#{field}") } } title: { guard: ->(obj, args, ctx) { ... }, not_authorized: ->(type, field) { nil } # simply return nil if not authorized, no errors } } } def self.guard(type, field) RULES.dig(type, field, :guard) end def self.not_authorized_handler(type, field) RULES.dig(type, field, :not_authorized) || RULES.dig(type, :'*', :not_authorized) end end Schema = GraphQL::Schema.define do query QueryType mutation MutationType use GraphQL::Guard.new( policy_object: GraphqlPolicy, not_authorized: ->(type, field) { handler = GraphqlPolicy.not_authorized_handler(type, field) handler.call(type, field) } ) end
It's possible to hide fields from being introspectable and accessible based on the context. For example:
PostType = GraphQL::ObjectType.define do name "Post" field :id, !types.ID field :title, types.String do # The field "title" is accessible only for beta testers mask ->(ctx) { ctx[:current_user].beta_tester? } end end
Add this line to your application's Gemfile:
gem 'graphql-guard'
And then execute:
$ bundle
Or install it yourself as:
$ gem install graphql-guard
It's possible to test fields with guard
in isolation:
# Your type QueryType = GraphQL::ObjectType.define do name "Query" field :posts, !types[!PostType], guard ->(obj, args, ctx) { ... } end # Your test require "graphql/guard/testing" posts = QueryType.field_with_guard('posts') result = posts.guard(obj, args, ctx) expect(result).to eq(true)
If you would like to test your fields with policy objects:
# Your type QueryType = GraphQL::ObjectType.define do name "Query" field :posts, !types[!PostType] end # Your policy object class GraphqlPolicy def self.guard(type, field) ->(obj, args, ctx) { ... } end end # Your test require "graphql/guard/testing" posts = QueryType.field_with_guard('posts', GraphqlPolicy) result = posts.guard(obj, args, ctx) expect(result).to eq(true)
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.
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.
The gem is available as open source under the terms of the MIT License.
Everyone interacting in the Graphql::Guard project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.