Weather API — Complete Example

Fetches weather from Open-Meteo, caches results in SQLite. Source: examples/09_weather_api.rs and examples/10_weather_users_api.rs.

Run:

cargo run --example 09_weather_api --features axum
cargo run --example 10_weather_users_api --features axum

Architecture

AppConfig (#[injectable(ctor)] reads env)
    ↓
make_pool (#[injectable(factory)])   make_http_client (#[injectable(factory)])
    ↓                               ↓
WeatherService (#[injectable] ← pool, client)
    ↓
UserService (#[injectable] ← pool, Arc<WeatherService>)

Pool factory with sqlite::memory: note

#[injectable(factory)]
async fn make_pool(cfg: Inject<AppConfig>) -> Result<Pool<Sqlite>, InjectableError> {
    sqlx::sqlite::SqlitePoolOptions::new()
        .max_connections(1)        // REQUIRED for sqlite::memory:
        .idle_timeout(None)        // prevent connection recycling
        .max_lifetime(None)
        .connect(&cfg.database_url)
        .await
        .map_err(|e| InjectableError::ConstructionFailed {
            type_name: "SqlitePool",
            reason: e.to_string(),
        })
}

HTTP client factory

async fn make_http_client(_ctx: &ResolveContext)
    -> Result<reqwest::Client, InjectableError>
{
    reqwest::Client::builder()
        .timeout(std::time::Duration::from_secs(10))
        .user_agent("injectable-example/1.0")
        .build()
        .map_err(|e| InjectableError::ConstructionFailed {
            type_name: "reqwest::Client",
            reason: e.to_string(),
        })
}

Key patterns

Pattern	Where used
#[injectable(factory)] for pool	make_pool
use_factory_async field	pool on WeatherService
use_factory_sync field	client on WeatherService (sync factory)
Arc<WeatherService> dep	weather_service field on UserService
#[injectable(post_construct)] migration	WeatherService, UserService
#[injectable(pre_destruct)] close	Pool close
Custom AppState	Implements InjectableState

See full sources in examples/.