GraphQL API in Clojure

GraphQL API in Clojure

lagénorhynque (defprofile lagénorhynque :aliases [ :languages :interests ] [Clojure Common-Lisp Scheme Haskell English français] [programming Love-Live! language-learning/linguistics law mathematics] :committing [github.com/lagenorhynque/duct.module.pedestal] :contributing [github.com/japan-clojurians/clojure-site-ja])

• https://twitter.com/lagenorhynque

1. GraphQL GraphQL query GraphQL schema 2. API implementation project structure API server GraphQL implementation

Clojure Lacinia GraphQL API

• https://qiita.com/lagenorhynque/items/eebb9a36859789520dbf

example lagenorhynque/aqoursql: AqoursQL, an example GraphQL API based on Lacinia-Pedestal & Duct

• https://github.com/lagenorhynque/aqoursql

GraphQL venia & edn

GraphQL query venia

• https://github.com/Vincit/venia

query: member_by_id { member_by_id(id: 1) { id name organization_id organization_name } }

response (JSON) { "data": { "member_by_id": { "id": 1, "name": " ", "organization_id": 1, "organization_name": " } } } "

GraphiQL

Clojure REPL dev> (q #:venia{:queries [[:member_by_id {:id 1} [:id :name :organization_id :organization_name]]]}) {:data {:member_by_id {:id 1, :name " ", :organization_id 1, :organization_name " "}}}

utility function q (defn q ([query] (q query nil)) ([query variables] (lacinia/execute (:aqoursql.graphql/schema system) (venia/graphql-query query) variables {:db (:duct.database.sql/hikaricp system)}))) venia.core/graphql­query com.walmartlabs.lacinia/execute

• https://github.com/Vincit/venia/blob/v0.2.5/src/venia/core.cljc#L209-L213
• https://github.com/walmartlabs/lacinia/blob/v0.31.0/src/com/walmartlabs/lacinia.clj#L70-L121

query: songs { songs { name artist { name members { name } } } }

response (JSON) { "data": { "songs": [ { "name": " "artist": { "name": "Aqours", "members": [ { "name": " }, ... ] } }, ... ] } ", "

GraphiQL

Clojure REPL
dev> (q #:venia{:queries [[:songs
[:name
[:artist
[:name
[:members
[:name]]]]]]]})
{:data
{:songs
({:name "
",
:artist
{:name "Aqours",
:members
({:name "
"}
...

GraphQL schema edn

• https://github.com/edn-format/edn

object de nition: Member """ """ type Member { """ ID""" id: Int! """ """ name: String! """ ID""" organization_id: Int! """ """ organization_name: String! }

resources/aqoursql/graphql-schema.edn {:objects {:Member {:description " " :fields {:id {:type (non-null Int) :description " ID"} :name {:type (non-null String) :description " "} :organization_id {:type (non-null Int) :description " ID"} :organization_name {:type (non-null String) :description " "}}}}}

• https://github.com/lagenorhynque/aqoursql/blob/master/resources/aqoursql/graphql-schema.edn

object de nition: Song """ """ type Song { """ ID""" id: Int! """ """ name: String! """" ID"" artist_id: Int! """ """ artist: Artist! """ (YYYY-MM-DD)""" release_date: String! }

resources/aqoursql/graphql-schema.edn {:objects {:Song {:description " " :fields {:id {:type (non-null Int) :description " ID"} :name {:type (non-null String) :description " "} :artist_id {:type (non-null Int) :description " ID"} :artist {:type (non-null :Artist) :description " "} :release_date {:type (non-null String) :description " (YYYY-MM-DD)"}}}}}

• https://github.com/lagenorhynque/aqoursql/blob/master/resources/aqoursql/graphql-schema.edn

query de nition: member_by_id type Query { """ID member_by_id( " ID" id: Int! ): Member } """

resources/aqoursql/graphql-schema.edn {:queries {:member_by_id {:type :Member :description "ID " :args {:id {:type (non-null Int) :description " ID"}} :resolve :query/member-by-id}}}

• https://github.com/lagenorhynque/aqoursql/blob/master/resources/aqoursql/graphql-schema.edn

query de nition: songs type Query { """ """ songs( " ( )" name: String ): [Song] }

{:queries {:songs {:type (list :Song) :description " " :args {:name {:type String :description " :resolve :query/songs}}} ( )"}}

API implementation Duct + Pedestal + Lacinia

project structure Duct

• https://github.com/duct-framework/duct

Clojure Duct

• https://qiita.com/lagenorhynque/items/8201c116c87b40eb9c22

resources/aqoursql/con g.edn {:duct.profile/base {:duct.core/project-ns aqoursql :duct.server/pedestal { ... } :aqoursql.graphql/schema {} :aqoursql.graphql/service { ... }} :duct.profile/dev #duct/include "dev" :duct.profile/test #duct/include "test" :duct.profile/local #duct/include "local" :duct.profile/prod {} :duct.module/logging {} :duct.module/sql { ... } :duct.module/pedestal {}}

• https://github.com/lagenorhynque/aqoursql/blob/master/resources/aqoursql/config.edn

API server Pedestal duct.module.pedestal

• https://github.com/pedestal/pedestal
• https://github.com/lagenorhynque/duct.module.pedestal

Clojure Pedestal

• https://qiita.com/lagenorhynque/items/fbd66ebaa0352ec4253d

resources/aqoursql/con g.edn {:duct.profile/base {:duct.core/project-ns aqoursql :duct.server/pedestal {:base-service #ig/ref :aqoursql.graphql/service :service #:io.pedestal.http{:join? true :host #duct/env "SERVER_HOST" :port #duct/env ["SERVER_PORT" Int :or 8888]}} ... } ... :duct.module/pedestal {}}

• https://github.com/lagenorhynque/aqoursql/blob/master/resources/aqoursql/config.edn

GraphQL implementation Lacinia Lacinia-Pedestal

• https://github.com/walmartlabs/lacinia
• https://github.com/walmartlabs/lacinia-pedestal

resources/aqoursql/con g.edn {:duct.profile/base {:duct.core/project-ns aqoursql ... :aqoursql.graphql/schema {} :aqoursql.graphql/service {:schema #ig/ref :aqoursql.graphql/schema :options {:graphiql true :app-context {:db #ig/ref :duct.database/sql} :env :prod}}} ... }

• https://github.com/lagenorhynque/aqoursql/blob/master/resources/aqoursql/config.edn

src/aqoursql/graphql.clj
(defmethod ig/init-key ::schema
[_ _]
(-> (io/resource "aqoursql/graphql-schema.edn")
slurp
edn/read-string
(util/attach-resolvers resolver-map)
schema/compile))
(defmethod ig/init-key ::service
[_ {:keys [schema options]}]
(lacinia/service-map schema options))

• https://github.com/lagenorhynque/aqoursql/blob/master/src/aqoursql/graphql.clj

resolver (function) src/aqoursql/graphql.clj (def resolver-map {:query/artist-by-id artists/fetch-artist-by-id :query/artists artists/list-artists :query/member-by-id members/fetch-member-by-id :query/members members/list-members :query/song-by-id songs/fetch-song-by-id :query/songs songs/list-songs})

• https://github.com/lagenorhynque/aqoursql/blob/master/src/aqoursql/graphql.clj

src/aqoursql/resolver/members.clj (defn fetch-member-by-id [{:keys [db]} {:keys [id]} _] (db.member/find-member-by-id db id)) resolver function spec (s/fdef resolver :args (s/cat :app-context map? :arguments (s/nilable map?) :resovled-value (s/nilable map?)))

• https://github.com/lagenorhynque/aqoursql/blob/master/src/aqoursql/resolver/members.clj

boundary (DB) src/aqoursql/boundary/db/member.clj (s/def ::id nat-int?) (s/def ::name string?) (s/def ::organization_id ::organization/id) (s/def ::organization_name ::organization/name) (s/def ::artist_id ::artist/id) (s/def ::artist_ids (s/coll-of ::artist/id)) (s/def ::member (s/keys :req-un [::id ::name ::organization_id] :opt-un [::organization_name ::artist_id]))

• https://github.com/lagenorhynque/aqoursql/blob/master/src/aqoursql/boundary/db/member.clj

(s/fdef find-member-by-id :args (s/cat :db ::db/db :id ::id) :ret (s/nilable ::member)) ... (defprotocol Member (find-member-by-id [db id]) ... )

dev> (aqoursql.boundary.db.member/find-member-by-id
(:duct.database.sql/hikaricp system) 1)
{:id 1, :name "
", :organization_id 1,
:organization_name "
"}
dev> (aqoursql.resolver.members/fetch-member-by-id
{:db (:duct.database.sql/hikaricp system)}
{:id 1} nil)
{:id 1, :name "
", :organization_id 1,
:organization_name "
"}
dev> (q #:venia{:queries [[:member_by_id {:id 1}
[:name
:organization_name]]]})
{:data {:member_by_id {:name "
",
:organization_name "
"}}}

Further Reading Lacinia Lacinia Lacinia-Pedestal: Expose Lacinia GraphQL as Pedestal endpoints Clojure Lacinia GraphQL API example: lagenorhynque/aqoursql Clojure GraphQL Lacinia Tips

• https://github.com/lagenorhynque/aqoursql
• https://github.com/walmartlabs/lacinia
• https://github.com/walmartlabs/lacinia-pedestal
• https://qiita.com/lagenorhynque/items/eebb9a36859789520dbf
• https://qiita.com/223kazuki/items/ba4ba84e2da1daea3b52
• https://qiita.com/223kazuki/items/50e5f62f19fed751ba40

Duct Duct duct.module.pedestal: Duct module for Pedestal Clojure Duct

• https://github.com/duct-framework/duct
• https://github.com/lagenorhynque/duct.module.pedestal
• https://qiita.com/lagenorhynque/items/8201c116c87b40eb9c22

Pedestal Pedestal Clojure Pedestal

• http://pedestal.io/
• https://qiita.com/lagenorhynque/items/fbd66ebaa0352ec4253d

GraphQL venia: Clojure(Script) graphql query generation GraphQL | A query language for your API How to GraphQL - The Fullstack Tutorial for GraphQL GraphQL ─ REST API Learning GraphQL

• https://github.com/Vincit/venia
• https://graphql.org/
• https://www.howtographql.com/
• https://employment.en-japan.com/engineerhub/entry/2018/12/26/103000
• http://shop.oreilly.com/product/0636920137269.do