GraphQL backend with Ruby

Implementing GraphQL API with Ruby

Transcript

1. GraphQL backend with Ruby Daniel Hejl
2. productboard
3. gem 'graphql'
4. GraphQL::Pro
5. PostType = GraphQL::ObjectType.define do name "Post" description "A blog post" field :id, !types.ID field :title, !types.String field :body, !types.String field :author, !AuthorType field :comments, types[!CommentType] field :teaser, types.String, "The teaser of the Post" do resolve ->(post, args, ctx) { post.body[0, 40] } end end
6. QueryType = GraphQL::ObjectType.define do name "Query" description "The query root of this schema" field :post do type PostType argument :id, !types.ID description "Find a Post by ID" resolve ->(obj, args, context) { Post.find(args["id"]) } end field :posts do type types[PostType] resolve ->(obj, args, context) { Post.all } end end Schema = GraphQL::Schema.define do query QueryType end
7. def create query_string = params[:query] query_variables = params[:variables] || {} document = GraphQL.parse(query_string) result = Schema.execute(document: document, variables: query_variables) render json: result end
8. Mutations
9. PostInputType = GraphQL::InputObjectType.define do name "PostInputType" description "Properties for creating a Post" argument :title, !types.String argument :body, types.String end
10. MutationRoot = GraphQL::ObjectType.define do name "Mutation" field :addPost, Post do description "Adds a Post." argument :post, PostInputType resolve ->(t, args, c) { Post.create( title: args['post']['title'], body: args['post']['body'] ) } end end Schema = GraphQL::Schema.define do mutation MutationRoot end
11. PostType = GraphQL::ObjectType.define do # ... field :errors, types[types.String] do description "Reasons the object couldn't be created or updated" resolve ->(obj, args, ctx) { obj.errors.full_messages } end end
12. GraphiQL-Rails
14. Ok, but is it fast?
16. { query { posts { id title teaser author { name } } } }
17. { query { posts { id title teaser author { name } } } } QueryType = GraphQL::ObjectType.define do name "Query" description "The query root of this schema" field :post do type PostType argument :id, !types.ID description "Find a Post by ID" resolve ->(obj, args, context) { Post.find(args["id"]) } end field :posts do type types[PostType] resolve ->(obj, args, context) { Post.all } end end
18. { query { posts { id title teaser author { name } } } } QueryType = GraphQL::ObjectType.define do name "Query" description "The query root of this schema" field :post do type PostType argument :id, !types.ID description "Find a Post by ID" resolve ->(obj, args, context) { Post.find(args["id"]) } end field :posts do type types[PostType] resolve ->(obj, args, context) { Post.all } end end
19. { query { posts { id title teaser author { name } } } } Post Load (2.3ms) SELECT "posts".* FROM "posts"
20. { query { posts { id title teaser author { name } } } } PostType = GraphQL::ObjectType.define do name "Post" description "A blog post" field :id, !types.ID field :title, !types.String field :body, !types.String field :author, !AuthorType field :comments, types[!CommentType] field :teaser, types.String, do resolve ->(post, args, ctx) { post.body[0, 40] } end end
21. { query { posts { id title teaser author { name } } } } Author Load (1.4ms) SELECT "authors".* FROM "authors" WHERE "authors"."id" = $1 LIMIT 1 [["id", 12]] Author Load (1.2ms) SELECT "authors".* FROM "authors" WHERE "authors"."id" = $1 LIMIT 1 [["id", 13]] Author Load (1.3ms) SELECT "authors".* FROM "authors" WHERE "authors"."id" = $1 LIMIT 1 [["id", 14]]
22. gem 'graphql-batch'
23. class RecordLoader < GraphQL::Batch::Loader def initialize(model) @model = model end def perform(ids) @model.where(id: ids).each { |record| fulfill(record.id, record) } ids.each { |id| fulfill(id, nil) unless fulfilled?(id) } end end # Then, in your type definition field :author, !AuthorType do resolve -> (post, args, context) { RecordLoader.for(Author).load(post.author_id) } end
24. { query { posts { id title teaser author { name } } } } Author Load (1.9ms) SELECT "authors".* FROM "authors" WHERE "authors"."id" = IN (12, 13, 14)
25. gem 'graphql-query-resolver'
26. gem 'graphql-active_record_batcher'
27. http://mgiroux.me/2016/graphql-query-caching-with-rails/ Query parsing & caching def create query_string = params[:query] query_variables = params[:variables] || {} document = get_document(query_string) result = Schema.execute(document: document, variables: query_variables) render json: result end def get_document(query_string) cache_key = Digest::MD5.hexdigest(query_string) document = Rails.cache.fetch(cache_key) unless document document = GraphQL.parse(query_string) Rails.cache.write(cache_key, document) end document end
28. Persisted queries WebRepository = GraphQL::Pro::Repository.define do schema MySchema path Rails.root.join("app/graphql/documents/") end result = WebRepository.execute( operation_name: params[:operationName] variables: ensure_hash(params[:variables]) ) render json: result
29. gem 'graphql-persisted_documents'
31. Security? $
32. Limiting Visibility top_secret = ->(schema_member, ctx) { schema_member.metadata[:internal_only]} MySchema.execute(query_string, except: top_secret) # OR filter = PermissionWhitelist.new(@current_user) MySchema.execute(query_string, only: filter) class PermissionWhitelist def initialize(user) @user = user end def call(schema_member, ctx) Permissions.allowed?(user, schema_member) end end
33. Evil clients
34. Timeouts & throttling MySchema.middleware << GraphQL::Schema::TimeoutMiddleware.new(max_seconds: 2) do |err, query| Rails.logger.info("GraphQL Timeout: #{query.query_string}") end
35. Prevent deeply nested queries # Schema-level: MySchema = GraphQL::Schema.define do # ... max_depth 10 end # Query-level, which overrides the schema-level setting: MySchema.execute(query_string, max_depth: 10)
36. Calculate complexity # Constant complexity: field :top_score, types.Int, complexity: 10 # Dynamic complexity: field :top_scorers, types[PlayerType] do argument :limit, types.Int, default_value: 5 complexity ->(ctx, args, child_complexity) { if ctx[:current_user].staff? 0 else args[:limit] * child_complexity end } end MySchema = GraphQL::Schema.define do # ... max_complexity 100 end
37. Monitoring & instrumentation &
38. Custom execution decorator (or GraphQL::Pro) https://eatcodeplay.com/graphql-performance-monitoring-with-new-relic-20070571a5d2 class SerialExecutionWithNewRelic < GraphQL::Query::SerialExecution def execute(ast_operation, root_type, query_object) irep_root = query_object.internal_representation[ast_operation.name] begin ::NewRelic::Agent.set_transaction_name(newrelic_name(irep_root)) ::NewRelic::Agent.add_custom_attributes(provided_variables(query_object)) rescue Exception => e Rails.logger.error('NewRelic set_transaction_name and add_custom_attributes failure: ' + e.message) end super end def newrelic_name(irep_root) name_to_report = irep_root.name || irep_root.children.keys.join(' - ') ['GraphQL', name_to_report].join(' - ') end def provided_variables(query_object) variables = query_object.variables.instance_variable_get(:@provided_variables) || {} ActionDispatch::Http::ParameterFilter.new(Rails.application.config.filter_parameters).filter(variables) end end
39. Apollo Optics
41. Thanks a lot! daniel@productboard.com