## Compile-time dependency inject
spring-rs provides a special Component - [Service](https://docs.rs/spring/latest/spring/plugin/service/index.html), which supports injecting dependent components at compile time.
Like the following example, `UserService` only needs to derive the `Service` feature. In order to distinguish the injected dependencies, you need to specify whether the dependency is a Component or a Config through the attribute macros `#[component]` and `#[config]`.
```rust
use spring_sqlx::ConnectPool;
use spring::config::Configurable;
use spring::plugin::service::Service;
use serde::Deserialize;
#[derive(Clone, Configurable, Deserialize)]
#[config_prefix = "user"]
struct UserConfig {
username: String,
project: String,
}
#[derive(Clone, Service)]
struct UserService {
#[component]
db: ConnectPool,
#[config]
config: UserConfig,
}
```
For the complete code, see [`dependency-inject-example`](https://github.com/spring-rs/spring-rs/tree/master/examples/dependency-inject-example).