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Service registration

injector.ListProvidedServices() and injector.ListInvokedServices() return every service registered on an injector and, separately, every service that has actually been instantiated so far. Comparing the two lists is the fastest way to spot a service that's registered but never used, or one that's missing entirely.

Spec​

injector.ListProvidedServices() []do.ServiceDescription
injector.ListInvokedServices() []do.ServiceDescription

type ServiceDescription struct {
	ScopeID   string
	ScopeName string
	Service   string
}

Service name​

Each service is identified in the DI container by a slug.

When using implicit naming, the do framework infers the service name from the type, by using the go-type-to-string library.

For debugging purposes, you might want to print the service name.

Play: https://go.dev/play/p/g549GqBbj-n

i := do.New()

do.Provide(i, func(i do.Injector) (*MyService, error) {
    return &MyService{}, nil
})

println(do.NameOf[*MyService]())

Output:

// *github.com/samber/example.MyService

Provided services​

For debugging purposes, the list of services provided to the container can be printed:

Play: https://go.dev/play/p/e_oxd7b-q9h

i := do.New()

do.Provide(i, func(i do.Injector) (*MyService, error) {
    return &MyService{}, nil
})
do.ProvideNamed(i, "a-number", 42)

services := i.ListProvidedServices()
println(services)

Output:

[
   {ScopeID: "xxxxx", ScopeName: "[root]", Service: "*github.com/samber/example.MyService"},
   {ScopeID: "xxxxx", ScopeName: "[root]", Service: "a-number"}
]

Invoked services​

For debugging purposes, the list of invoked services can be printed:

Play: https://go.dev/play/p/pJcJGOF5zeK

i := do.New()

do.Provide(i, func(i do.Injector) (*MyService, error) {
    return &MyService{}, nil
})
do.ProvideNamed(i, "a-number", 42)

services := i.ListInvokedServices()
println(services)

Output:

[
   {ScopeID: "xxxxx", ScopeName: "[root]", Service: "a-number"}
]

In the example above, the lazy-loaded service *MyService has not been invoked.

Finding registered-but-unused services​

Diffing ListProvidedServices() against ListInvokedServices() is a quick way to find dead registrations during cleanup: anything present in the first list but absent from the second was registered but never actually invoked in that run. This doesn't necessarily mean the service is unused in general — a service invoked only on a rarely-hit code path won't appear until that path runs — but it's a good starting point for auditing a container after a refactor.

See also the scope tree to visualize how these services relate across scopes, and service dependencies to inspect a single service's dependency chain.