Dependency Graph

The graph is validated automatically at Container::builder().build().

Error types

match container_result {
    Err(InjectableError::GraphValidationFailed { errors }) => {
        for e in &errors {
            eprintln!("Graph error: {e}");
        }
    }
    Err(e) => eprintln!("Build error: {e}"),
    Ok(c) => { /* use container */ }
}

Common errors and fixes

Circular dependency

`UserService` → `OrderService` → `UserService` (cycle)

Fix: introduce an interface layer or refactor the dependency.

Missing registration

`UserService` depends on `EmailClient`, which is not registered

Fix: add #[injectable] to EmailClient or register via DynProvider.

Scope mismatch

Singleton `UserService` cannot depend on Transient `RequestContext`

Fix: make RequestContext singleton, or make UserService transient.

Inspect registered types

let container = Container::builder().build().await?;
let types = container.registered_types();
println!("Registered: {:?}", types);
// ["Database", "UserService", "OrderService", …]

Use container! macro for compile-time validation

use injectable::container;

container! {
    Database,
    Cache { scope: "transient" },
    UserService { deps: [Database, Cache] },
}
// Compile error if circular deps, scope mismatches, or missing deps.

Check specific type is registered

assert!(container.registered_types().contains(&"Database"));

// Non-failing check:
let result: Option<Database> = container.try_resolve().await?;
if result.is_none() {
    println!("Database not registered");
}

See guides/12-dependency-graph.md.