🌓 Faces

Faces filters a structure using field tags. This is useful when you want to create several versions of the same structure without duplicating it. A use case could be when creating an API and not wanting to provide private information to end users.

Usage

You can find many examples in the test file but here is a simple one:

// A simple user structure
type User struct {
  Email    string
  Password string `faces:"private"` // The password is part of the user's private face.
}

// Create a user
user := &User{
  Email:    "foo@bar.com",
  Password: "private-password",
}

// Filter the user
faces.Reveal(user, "public")

fmt.Printf("%#v", user)
// Output:
// &main.User{Email:"foo@bar.com", Password:""}

As you can see, the password is now hidden (or at least, reset). This package can be combined with the JSON package as in the example below:

// A simple user structure
type User struct {
  Email    string `json:"email"`
  Password string `faces:"private" json:"password,omitempty"` // We do not want to display the field when using json
}

// Create a user
user := &User{
  Email:    "foo@bar.com",
  Password: "private-password",
}

// Filter the user
faces.Reveal(user, "public")

// Convert the user to JSON
b, _ := json.Marshal(user)

fmt.Println(string(b))
// Output:
// {"email":"foo@bar.com"}

Benchmarks

Here are the results of a benchmark executed on my laptop. The results do not represent an absolute truth but will allow me not to regress during future updates.

goos: darwin
goarch: amd64
pkg: github.com/remyduthu/faces
cpu: Intel(R) Core(TM) i7-8559U CPU @ 2.70GHz
BenchmarkReveal-8                                  	 5044090	       243.2 ns/op	      40 B/op	       4 allocs/op
BenchmarkRevealWithSlice-8                         	 2272608	       515.0 ns/op	     104 B/op	       9 allocs/op
BenchmarkRevealWithMap-8                           	 1452736	       825.9 ns/op	     256 B/op	      12 allocs/op
BenchmarkRevealWithNestedStructure-8               	 2004470	       596.9 ns/op	     112 B/op	      10 allocs/op
BenchmarkRevealWithArrayOfStructures-8             	 1725184	       699.8 ns/op	     120 B/op	      11 allocs/op
BenchmarkRevealWithoutTags-8                       	537072181	         2.258 ns/op	       0 B/op	       0 allocs/op
BenchmarkRevealWithSomethingElseThanAStructure-8   	100000000	        10.50 ns/op	       0 B/op	       0 allocs/op
PASS
coverage: 100.0% of statements