harmony/harmony_config/examples/basic.rs

//! Basic example showing harmony_config with SQLite backend
//!
//! This example demonstrates:
//! - Zero-setup SQLite backend (no configuration needed)
//! - Using the `#[derive(Config)]` macro
//! - Environment variable override (HARMONY_CONFIG_TestConfig overrides SQLite)
//! - Direct set/get operations (prompting requires a TTY)
//!
//! Run with:
//! - `cargo run --example basic` - creates/reads config from SQLite
//! - `HARMONY_CONFIG_TestConfig='{"name":"from_env","count":42}' cargo run --example basic` - uses env var

use std::sync::Arc;

use harmony_config::{Config, ConfigClient, EnvSource, SqliteSource};
use log::info;
use schemars::JsonSchema;
use serde::{Deserialize, Serialize};

#[derive(Debug, Clone, Serialize, Deserialize, JsonSchema, Config)]
struct TestConfig {
    name: String,
    count: u32,
}

impl Default for TestConfig {
    fn default() -> Self {
        Self {
            name: "default_name".to_string(),
            count: 0,
        }
    }
}

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    env_logger::init();

    // Namespace the SQLite file so this example's state doesn't
    // collide with other harmony binaries that also use SqliteSource.
    let sqlite = SqliteSource::for_namespace("harmony_config-basic-example").await?;
    let manager = ConfigClient::new(vec![Arc::new(EnvSource), Arc::new(sqlite)]);

    info!("1. Attempting to get TestConfig (expect NotFound on first run)...");
    match manager.get::<TestConfig>().await {
        Ok(config) => {
            info!("   Found config: {:?}", config);
        }
        Err(harmony_config::ConfigError::NotFound { .. }) => {
            info!("   NotFound - as expected on first run");
        }
        Err(e) => {
            info!("   Error: {:?}", e);
        }
    }

    info!("\n2. Setting config directly...");
    let config = TestConfig {
        name: "from_code".to_string(),
        count: 42,
    };
    manager.set(&config).await?;
    info!("   Set config: {:?}", config);

    info!("\n3. Getting config back from SQLite...");
    let retrieved: TestConfig = manager.get().await?;
    info!("   Retrieved: {:?}", retrieved);

    info!("\n4. Using env override...");
    info!("   Env var HARMONY_CONFIG_TestConfig overrides SQLite");
    let env_config = TestConfig {
        name: "from_env".to_string(),
        count: 99,
    };
    unsafe {
        std::env::set_var(
            "HARMONY_CONFIG_TestConfig",
            serde_json::to_string(&env_config)?,
        );
    }
    let from_env: TestConfig = manager.get().await?;
    info!("   Got from env: {:?}", from_env);
    unsafe {
        std::env::remove_var("HARMONY_CONFIG_TestConfig");
    }

    info!("\nDone! Config persisted at ~/.local/share/harmony/config/config.db");

    Ok(())
}