Rust + GraphQL + Juniper + Diesel + Postgres + Actix

Yes, I know that this is a borderline absurd web stack for the ubiquitous TODO application but I had a lot of trouble getting this all to work. I started using these things for a more ambitious project and I'd love to spare you the trouble. So here's some basic boilerplate to get you up and running.

Components

Here's what does what:

Component	Tool/lib
Web server	actix-web
Database	PostgreSQL
SQL engine	Diesel
GraphQL library	Juniper
GraphQL UI	GraphQL Playground

Run locally

Before you get started, make sure that you have PostgreSQL, Rust, Cargo, and the Diesel CLI installed and that you have Postgres running somewhere.

# Fetch the repo
git clone https://github.com/lucperkins/rust-actix-diesel-postgres-juniper
cd rust-actix-diesel-postgres-juniper

# Set up the database
cp .env.example .env # Modify this file to match your Postgres installation

diesel setup
diesel migration run

cargo run # could take a while!

The DATABASE_URL can be any Postgres installation. For my purposes, I have it set to postgres://localhost:5432/todos.

Once the server is running, you can access the GraphQL Playground UI at http://localhost:4000/graphql.

Schema

The server implements the following GraphQL schema:

type Todo {
  id: ID!
  task: String!
  done: Boolean!
}

input CreateTodoInput {
  task: String!
  done: Boolean
}

type Query {
  allTodos: [Todo!]!
  getTodoById(id: Int): Todo
}

type Mutation {
  createTodo(input: CreateTodoInput): Todo
  markTodoAsDone(id: Int): Todo
  markTodoAsNotDone(id: Int): Todo
}

schema {
  Query
  Mutation
}

Tour of the codebase

File	What it provides
`context.rs`	The GraphQL context that handles query execution
`data.rs`	A `Todos` struct and some helper functions encapsulate the Diesel-powered Postgres querying logic
`db.rs`	The connection pool that handles the Postgres connection
`endpoints.rs`	The `/graphql` HTTP endpoint that makes GraphQL and the GraphQL Playground work
`graphql.rs`	The `Query`, `Mutation`, and `Schema` objects that undergird the GraphQL interface
`lib.rs`	Just the standard `lib.rs`
`main.rs`	Actix HTTP server setup
`models.rs`	All of the data types used for querying Postgres and providing GraphQL results
`schema.rs`	The Diesel-generated table schema

Future TODOs

Get it? Anyway, here's some areas for improvement (pull requests very much welcome):

Error handling — Right now errors basically propagate directly from Diesel/Postgres into the GraphQL JSON output, which is subpar. If any of you can point me to good educational resources on this, please file an issue!
Better execution engine — The server uses the extremely powerful actix-web but the actual DB interactions don't use Actix actors and it'd take this setup to the next level if they did.
Use macros for schema generation — The powerful juniper_from_schema macro could help reduce boilerplate and improve development velocity.

Acknowledgments

I'm basically a beginner with Rust and would not have been able to put this together without peeking long and hard at the example projects and blog posts listed below. The lower-level bits you see here are basically stolen from BrendanBall. All that I've added is the Todos data construct for executing queries.

lucperkins/rust-graphql-juniper-actix-diesel-postgres

lucperkins

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