atrg-db

Database layer for at-rust-go: SQLite and PostgreSQL connection pooling and migrations.

Part of at-rust-go (atrg) — a batteries-included AT Protocol backend framework for Rust.

What this crate provides

DbPool — enum wrapping either sqlx::SqlitePool or sqlx::PgPool, the primary database handle used throughout atrg
connect(url) — create a connection pool, dispatching by URL scheme (sqlite://, sqlite::memory:, postgres://, postgresql://)
run_internal_migrations(pool) — apply atrg's own embedded migrations (sessions table, etc.) using the dialect matching the pool variant; idempotent on every startup
run_user_migrations(pool, dir) — discover and apply application-specific .sql migrations from a directory, silently skipping if the directory is missing or empty

The crate does not provide an ORM. Write SQL with sqlx.

Cargo features

Feature	Default	Effect
`sqlite`	✅	Pulls in the `sqlx/sqlite` driver and enables `DbPool::Sqlite`.
`postgres`	❌	Pulls in the `sqlx/postgres` driver and enables `DbPool::Postgres`.

At least one of sqlite or postgres must be enabled (a compile_error! fires otherwise). Enabling both is supported; connect() picks the backend at runtime from the URL scheme.

Usage

[dependencies]
# SQLite only (default)
atrg-db = "0.1"

# PostgreSQL only
atrg-db = { version = "0.1", default-features = false, features = ["postgres"] }

# Both backends — let `connect()` choose at runtime
atrg-db = { version = "0.1", features = ["postgres"] }

use atrg_db::DbPool;

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    // Pick the backend from the URL scheme
    let pool: DbPool = atrg_db::connect("sqlite://atrg.db").await?;
    // or: let pool = atrg_db::connect("postgres://user:pass@host/db").await?;

    // Run atrg internal migrations (sessions, OAuth state, etc.)
    atrg_db::run_internal_migrations(&pool).await?;

    // Run your app's migrations from the migrations/ directory
    atrg_db::run_user_migrations(&pool, std::path::Path::new("./migrations")).await?;

    // Borrow the underlying sqlx pool to run queries
    if let Some(sqlite) = pool.as_sqlite() {
        let row: (i32,) = sqlx::query_as("SELECT 1").fetch_one(sqlite).await?;
        assert_eq!(row.0, 1);
    }

    Ok(())
}

Connection defaults

SQLite

Setting	Value
Journal mode	WAL
Foreign keys	ON
Create if missing	Yes
Max connections	8

PostgreSQL

Setting	Value
Max connections	8

Migration conventions

atrg's internal migrations live in this crate under migrations/sqlite/ and migrations/postgres/. The set matching the active DbPool variant is run automatically. User migrations live in your project's migrations/ directory and are applied in filename order against the same backend:

migrations/
├── 0001_create_posts.sql
└── 0002_create_follows.sql

License

LGPL-3.0-only — see LICENSE.

atrg-db 0.1.3