func (a *App) RegisterBackend(b db.Backend) {
if b.Logger() == nil {
b.SetLogger(a.Logger())
}
isDefault := a.DefaultBackend() == nil
a.registry.AddBackend(b)
// If no backend was registered before, create a default UserService and FileService.
if isDefault && a.defaults {
if a.UserService() == nil {
a.BuildDefaultUserService(b)
}
if a.FileService() == nil {
a.BuildDefaultFileService(b)
}
if a.registry.TaskService() == nil {
a.BuildDefaultTaskService(b)
}
}
}