Container

Default options

The simplest way to start is to use the default parameters:

import "github.com/samber/do/v2"

injector := do.New()

Global container

For a quick start, you may use the default global container. This is highly discouraged in production.

import "github.com/samber/do/v2"

do.Provide(nil, ...)
do.Invoke(nil, ...)

// equivalent to:

do.Provide(do.DefaultRootScope, ...)
do.Invoke(do.DefaultRootScope, ...)

Register services on container initialization

The services can be assembled into a package, and then, imported all at once into a new container.

// pkg/stores/package.go

var Package = do.Package(
    do.Lazy(NewPostgreSQLConnectionService),
    do.Lazy(NewUserRepository),
    do.Lazy(NewArticleRepository),
    do.EagerNamed("repository.logger", slog.New(slog.NewTextHandler(os.Stdout, nil))),
)

// cmd/main.go

import "example/pkg/stores"

injector := do.New(stores.Package)

Custom options

import "github.com/samber/do/v2"

injector := do.NewWithOpts(&do.InjectorOpts{
    HookBeforeRegistration: []func(scope *do.Scope, serviceName string){},
    HookAfterRegistration:  []func(scope *do.Scope, serviceName string){},
    HookBeforeInvocation:   []func(scope *do.Scope, serviceName string){},
    HookAfterInvocation:    []func(scope *do.Scope, serviceName string, err error){},
    HookBeforeShutdown:     []func(scope *do.Scope, serviceName string){},
    HookAfterShutdown:      []func(scope *do.Scope, serviceName string, err error){},

    Logf: func(format string, args ...any) {
        // ...
    },

    HealthCheckParallelism:   100,
    HealthCheckGlobalTimeout: 1 * time.Second,
    HealthCheckTimeout:       100 * time.Millisecond,
})

Add hooks at runtime

Hooks can also be registered after the injector is created using helper methods on the root scope. These append to the corresponding hook lists in do.InjectorOpts and apply to subsequent registrations/invocations/shutdowns.

import "github.com/samber/do/v2"

injector := do.New()

// Registration hooks
injector.AddBeforeRegistrationHook(func(scope *do.Scope, serviceName string) {
    // ...
})
injector.AddAfterRegistrationHook(func(scope *do.Scope, serviceName string) {
    // ...
})

// Invocation hooks
injector.AddBeforeInvocationHook(func(scope *do.Scope, serviceName string) {
    // ...
})
injector.AddAfterInvocationHook(func(scope *do.Scope, serviceName string, err error) {
    // ...
})

// Shutdown hooks
injector.AddBeforeShutdownHook(func(scope *do.Scope, serviceName string) {
    // ...
})
injector.AddAfterShutdownHook(func(scope *do.Scope, serviceName string, err error) {
    // ...
})