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
Define a GraphQL schema:
# Define a type
class PostType < GraphQL::Schema::Object
field :id, ID, null: false
field :title, String, null: true
end
# Define a query
class QueryType < GraphQL::Schema::Object
field :posts, [PostType], null: false do
argument :user_id, ID, required: true
end
def posts(user_id:)
Post.where(user_id: user_id)
end
end
# Define a schema
class Schema < GraphQL::Schema
use GraphQL::Execution::Interpreter
use GraphQL::Analysis::AST
query QueryType
end
# Execute query
Schema.execute(query, variables: { userId: 1 }, context: { current_user: current_user })Add GraphQL::Guard to your schema:
class Schema < GraphQL::Schema use GraphQL::Execution::Interpreter use GraphQL::Analysis::AST query QueryType use GraphQL::Guard.new end
Now you can define guard for a field, which will check permissions before resolving the field:
class QueryType < GraphQL::Schema::Object
field :posts, [PostType], null: false do
argument :user_id, ID, required: true
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:
class PostType < GraphQL::Schema::Object
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:
class Schema < GraphQL::Schema use GraphQL::Execution::Interpreter use GraphQL::Analysis::AST 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
class PostType < GraphQL::Schema::Object
guard ->(obj, args, ctx) { ctx[:current_user].admin? } # <=== 3
field :title, String, null: true, guard: ->(obj, args, ctx) { ctx[:current_user].admin? } # <=== 1
end
class Schema < GraphQL::Schema
use GraphQL::Execution::Interpreter
use GraphQL::Analysis::AST
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
class PostType < GraphQL::Schema::Object
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
class PostType < GraphQL::Schema::Object
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:
class SchemaWithErrors < GraphQL::Schema
use GraphQL::Execution::Interpreter
use GraphQL::Analysis::AST
query QueryType
use GraphQL::Guard.new(
# By default it raises an error
# not_authorized: ->(type, field) do
# raise GraphQL::Guard::NotAuthorizedError.new("#{type}.#{field}")
# end
# Returns an error in the response
not_authorized: ->(type, field) do
GraphQL::ExecutionError.new("Not authorized to access #{type}.#{field}")
end
)
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
class Schema < GraphQL::Schema
use GraphQL::Execution::Interpreter
use GraphQL::Analysis::AST
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:
class PostType < GraphQL::Schema::Object
field :id, ID, null: false
field :title, String, null: true 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
class QueryType < GraphQL::Schema::Object
field :posts, [PostType], null: false, 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
class QueryType < GraphQL::Schema::Object
field :posts, [PostType], null: false
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.
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