Overview

LazyBE (Lazy Backend) is a collection of building blocks for quickly building a backend CRUD application. It provides macros and trait implementations that can be composed without being too opinionated about how to structure your application.

A typical backend application usually has boring parts, where you just need to do basic CRUD, and fun parts, where you get to do crazy stuff. LazyBE lets you skip the boring parts and focus on the fun ones.

Features

• Derive the data access layer from a struct
  • Uses sea-query and sqlx under the hood, which means you can use Postgres and SQLite (no MySQL support yet, but adding it should be trivial)
  • Automatically handles created_at and updated_at timestamps
  • See Minimal DAL example
• Derive axum endpoints from a struct (See Minimal API example)
• Derive OpenAPI specification from a struct (See Todo example)
• Custom validation support (See Validation example)
• Custom ID generation (See Custom ID example)
• Custom collection API support filter, sort, pagination (See Collection API example)
• Built-in support for JSON field (See JSON example)

A quick glance

Here’s a quick glance at what LazyBE looks like.

#[derive(Debug, Clone, Serialize, Deserialize, Entity, ToSchema)]
#[lazybe(table = "book", endpoint = "/books", derive_to_schema)]
pub struct Book {
    #[lazybe(primary_key)]
    pub id: u32,
    pub title: String,
    pub author: String,
    pub publication_date: NaiveDate,
    #[lazybe(created_at)]
    pub created_at: DateTime<Utc>,
    #[lazybe(updated_at)]
    pub updated_at: DateTime<Utc>,
}

The Entity macro derives traits and sibling types to implement commonly used backend layers.

• The attribute table = "book" defines the database table used for CRUD operations.
• The optional attribute endpoint = "/books" defines the URL path where the resource is exposed.
• The optional attribute derive_to_schema ensures that utoipa::ToSchema is derived for sibling types.
• The attribute #[lazybe(primary_key)] defines the primary key, allowing you to fetch a book by its ID.
• The attributes #[lazybe(created_at)] and #[lazybe(updated_at)] automatically timestamp when a record is created or updated.

With this macro, the following backend layers are automatically implemented:

1. Data access layer – using sqlx and sea-query
2. API layer – using axum and serde
3. OpenAPI specification – using utoipa

You can then expose Book on a REST API using axum like this:

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    let ctx = SqliteDbCtx;
    let pool = SqlitePool::connect("sqlite::memory:").await?;

    let openapi = OpenApiBuilder::new()
        .info(Info::new("Example", "0.1.0"))
        .servers(Some([Server::new("http://localhost:8080")]))
        .build()
        .merge_from(Book::get_endpoint_doc(None))
        .merge_from(Book::list_endpoint_doc(None))
        .merge_from(Book::create_endpoint_doc(None))
        .merge_from(Book::update_endpoint_doc(None))
        .merge_from(Book::replace_endpoint_doc(None))
        .merge_from(Book::delete_endpoint_doc(None));

    let app = Router::new()
        .merge(Redoc::with_url("/", openapi))
        .merge(Book::get_endpoint())
        .merge(Book::list_endpoint())
        .merge(Book::create_endpoint())
        .merge(Book::update_endpoint())
        .merge(Book::replace_endpoint())
        .merge(Book::delete_endpoint())
        .with_state(AppState { ctx, pool });

    let listener = tokio::net::TcpListener::bind("0.0.0.0:8080").await?;
    tracing::info!("Server is listening on 0.0.0.0:8080");
    lazybe::axum::serve(listener, app).await?;
    Ok(())
}

This will generate the following endpoints for the Book resource:

• POST /books – Create a new book and save it to the book table
• GET /books – Retrieve a collection of books
• GET /books/{id} – Retrieve a book by its ID
• PUT /books/{id} – Replace an existing book
• PATCH /books/{id} – Partially update an existing book
• DELETE /books/{id} – Delete a book by its ID

It will also generate the OpenAPI specification for the Book resource and serve it using the Redoc UI.

This is just a high-level overview. For a complete working example, see the minimal API example.

Documentation

• Example directory
• docs.rs

Releasing

# Prepare a new version, then merge the PR and create a tag
nix run .#bump

# Publish to crates.io
cargo publish -p lazybe-macros
cargo publish -p lazybe