pkg

Pkg

pkg is a collection of Go packages that make the life of a Gopher easier.

Installation

go get github.com/katallaxie/pkg

Go has a pretty good standard library, but there are some things that are missing. This collection of small packages is meant to fill those gaps.

Casting values

There is the typical case of pointers you need to deference. For example in the strict interfaces generated by oapi-codegen.

Somestruct {
  Field: cast.Ptr(req.Field),
}

Or the other way around, you have a pointer and you want to get the value or a default value.

SomeStruct {
  Field: cast.Value(req.Field),
}

Return a default value of a nil pointer.

type Foo struct {}
cast.Zero(Foo) // &Foo{}

Converting values

There is also always the case to covert a value to a specific other value.

// String converts a value to a string.
b := true
s := cast.String(b)

fmt.Println(s) // "true"

There are functions to convert int, string and bool values.

Operators

There is the implementation of various operators.

// Is the ternary operator.
utilx.IfElse(cond, 100, 0)

Optional

There is also the Option type which is a wrapper around a value that can be nil.

// Option is a wrapper around a value that can be nil.
a := optional.Some(100)
fmt.Println(a.String()) // true

Redux-inspired state management

This is a simple state management inspired by Redux.

// FootUpdate is a simple update.
type FooUpdate struct {}

// NoopState is a simple state of a store.
type NoopState struct {
	Name string `json:"name"`
}

store := redux.New(context.Background(), NoopState{Name: "foo"}, r)
defer s.Dispose()

state := NoopState{Name: "foo"}
store := redux.NewStore(context.Background(), State)

action := func() FooUpdate {
	return "foo"
}

store.Dispatch(action)
updates := store.Subscribe()

Databases

There are also more complex tools like the Database interface which enables to easliy implement database wrappers.

// Database provides methods for transactional operations.
type Database[R, W any] interface {
	// ReadTx starts a read only transaction.
	ReadTx(context.Context, func(context.Context, R) error) error
	// ReadWriteTx starts a read write transaction.
	ReadWriteTx(context.Context, func(context.Context, W) error) error

	Migrator
	io.Closer
}

Or a simple interface to implement servers. This takes for all signal and context handling.

s, _ := server.WithContext(ctx)
s.Listen(&srv{}, true)

serverErr := &server.ServerError{}
if err := s.Wait(); errors.As(err, &serverErr) {
  log.Print(err)
	os.Exit(1)
}

FGA with OpenFGA

There is also a package to work with the OpenFGA API.

// Store is an interface that provides methods for transactional operations on the authz database.
type Store[Tx any] interface {
	// Allowed checks if the user is allowed to perform the operation on the object.
	Allowed(context.Context, User, Object, Relation) (bool, error)
	// WriteTx starts a read write transaction.
	WriteTx(context.Context, func(context.Context, Tx) error) error
}

// StoreTx is an interface that provides methods for transactional operations on the authz database.
type StoreTx interface {
	// WriteTuple writes a tuple to the authz database.
	WriteTuple(context.Context, User, Object, Relation) error
	// DeleteTuple deletes a tuple from the authz database.
	DeleteTuple(context.Context, User, Object, Relation) error
}

This can be used with the package.

authzStore, err := authx.NewStore(fgaClient, authz.NewWriteTx())
if err != nil {
  return err
}

License

MIT