Provide & Inject

Components can share values with their descendants without passing them explicitly through props. A parent calls Provide to expose a value, and nested components can access it with Inject.

Providing a Value

Call Provide inside a lifecycle hook such as OnMount to make a value available to child components:

func (c *ParentComponent) OnMount() {
    c.Provide("user", "Ada")
}

Injecting a Value

Use Inject to search up the component tree for a matching key:

name, ok := core.Inject[string](c, "user")
if ok {
    // use name
}

If no provider is found, ok is false.

DI Container Injection

rfw v2 supports dependency injection via *t.Inject[T] struct fields and the composition.Container():

// Register a dependency globally
composition.Container().Provide("logger", myLogger)

// Inject into a struct field
type MyPage struct {
    composition.Component
    Logger *t.Inject[Logger]
}

When composition.New(&MyPage{}) is called, *t.Inject[T] fields are automatically resolved from the container using the lowercase field name as the key. The Logger field above resolves from Container().Get("logger").

Custom keys work by renaming the field:

type Page struct {
    composition.Component
    AppLog *t.Inject[Logger] // resolves from Container().Get("applog")
}

Full Example

parent := core.NewComponent("Parent", parentTpl, nil)
child := core.NewComponent("Child", childTpl, nil)

parent.Provide("answer", 42)
parent.AddDependency("child", child)

answer, _ := core.Inject[int](child, "answer") // 42

When to Use

• Provide/Inject for values that flow down the component tree (parent → child).
  
• *t.Inject[T] field for global singletons and services registered in the container.