prefer_db 0.3.4

# prefer_db

Database source for the [prefer](https://crates.io/crates/prefer) configuration library.

This crate provides a `DbSource` that implements `prefer::Source`, allowing configuration to be loaded from a database and layered with other prefer sources.

## Usage

Add to your `Cargo.toml`:

```toml
[dependencies]
prefer_db = "0.3"
prefer = "0.3"
async-trait = "0.1"
```

Implement the `ConfigLoader` trait for your database:

```rust
use prefer_db::{ConfigLoader, ConfigEntry, DbSource};
use async_trait::async_trait;

struct MyDbLoader {
    // your database connection
}

#[async_trait]
impl ConfigLoader for MyDbLoader {
    async fn load_config(&self) -> Option<ConfigEntry> {
        // Load from your database
        Some(ConfigEntry {
            format: "json".to_string(),
            data: r#"{"key": "value"}"#.to_string(),
        })
    }

    fn name(&self) -> &str {
        "my_database"
    }
}
```

Use with prefer's `ConfigBuilder`:

```rust
use prefer::Config;
use prefer_db::DbSource;

#[tokio::main]
async fn main() -> prefer::Result<()> {
    let config = Config::builder()
        .add_source(DbSource::new(MyDbLoader { /* ... */ }))
        .add_file("config.toml")  // File overrides DB
        .build()
        .await?;

    Ok(())
}
```

## Supported Formats

Configuration data can be stored in any of these formats:

- JSON
- TOML
- YAML

The format is determined by the `format` field in `ConfigEntry`.

## License

MIT