Fauna Adventures <!-- Put the link to this slide here so people can follow --> slide: https://hackmd.io/@gozala/fauna-adventures/ --- ## Supports GraphQL  Just import the schema and db is generate for you --- Schema In ```graphql type User { name: String! cars: [Car!] @relation } type Car { plate: String! owner: User! } ``` --- Schema Out ```graphql type Mutation { createCar(data: CarInput!): Car! deleteCar(id: ID!): Car updateCar(id: ID! data: CarInput!): Car # Same for User } input CarInput { plate: String! owner: CarOwnerRelation } input CarOwnerRelation { create: UserInput connect: ID } ``` --- (More) Schema Out ```graphql type Query { findUserByID(id: ID!): User findCarByID(id: ID!): Car } ``` 🤔 What's that `id` you speak of ? --- (Even more) Schema Out ```graphql type User { _id: ID! # <- here's our ID _ts: Long! name: String! cars(_size: Int, _cursor: String): CarPage! } type CarPage { data: [Car]! after: String before: String } ``` --- What I need 🥺 ```graphql input UserFilter { name: String } type Query { findCarsByUser(user: UserFilter): [Car!] } ``` What I get 😳 ```graphql type Query { findUserByID(id: ID!): User findCarByID(id: ID!): Car } ``` --- If you import that schema you'll get 😤  --- Why can't I just SQL 😭 ```sql SELECT * FORM cars INNER JOIN users ON user.id = cars.ownerid WHERE users.name = "gozala" ``` --- Enter  Fauna Query Language (FQL) --- Where our query looks like 🤮 ```fql Reduce(Lambda(["acc", "user"], Let({ owners: Match(Index("car_owner_by_user"), Var("user")), cars: Map(Paginate(Var("owners")), Lambda(["ref"], Get(Var("ref")))) }, Append(Var("cars"), Var("acc")))), [], Filter(Documents(Collection("User")), Lambda(["user"], Equals( Select(["data", "name"], Get(Var("user"))), "gozala")))) ``` And don't miss any of the commas or 💣 --- On the other hand it's uglier lisp 🤓 ```scheme (reduce (lambda (acc user) (let* ([owners (match index("car_owner_by_user") user)] [cars (map (paginate owners) (lambda ref (get ref)))]) (append cars acc))) [] (filter (documents (collections "User")) (lambda user (= (select ["data" "name"] user))))) ``` _P.S: Barely resisted writing lisp to FQL compiler_ --- Expose FQL query as User-defined function (UDF) via `@resolver` directive 🥳 ```graphql type Query { findCarsByUser(user: UserFilter): [Car!] @resolver } ``` --- How's GraphQL params looks in UDF ? 😅 ```fql Abort(Format('%@', Var("options"))) ``` Welcome to exception based debugging club! --- Modeling `N:M` relations are tricky 🧐 ```graphql type Block { hash: ID! @unique tokens: [Token!] @relation # ⚠️ Usually >1 token } type Token { id: String! @unique blocks: [Block!] @relation # ⚠️ May appear >1 block tokenID: String! tokenAsset: TokenAsset contract: TokenContract! @relation owner: Owner! @relation # ... } ``` 🚨 Arrays of refs aren't going to work 🚨 --- Fauna generates relation tables  Just Work™ in GraphQL --- VSCode Plugin 💚  Lets you execute FQL queries --- ## Challenges 😬 - Derived aggregate state (e.g. doc count) - Enforce invariants (type unions / state machines) - [Prevent generating GraphQL CRUD endpoints](https://forums.fauna.com/t/provide-a-mechanism-to-prevent-queries-and-mutations-being-autogenerated-for-a-given-type/35) - [Migrations]() --- ## Resources - [FQL Cheat Sheet](https://docs.fauna.com/fauna/current/api/fql/cheat_sheet) - [FQL for SQL users](https://docs.fauna.com/fauna/current/start/fql_for_sql_users) - [awesome-faunadb](https://github.com/n400/awesome-faunadb/) ---