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Faker: random fake data and struct generator for Go. #faker @pioz

Random fake data and struct generator for Go.

https://github.com/pioz/faker

  • More than 100 generator functions
  • Struct generator
  • Unique data generator
  • Builtin types support
  • Easily customizable
  • Zero dependencies
  • Recursive infinite loop detector
  • Benchmarks (coming soon)

Struct Builder Example

faker.SetSeed(622)

// Define a new builder
colorBuilder := func(params ...string) (interface{}, error) {
  return faker.Pick("Red", "Yellow", "Blue", "Black", "White"), nil
}

// Register a new builder named "color" for string type
err := faker.RegisterBuilder("color", "string", colorBuilder)
if err != nil {
  panic(err)
}

type Animal struct {
  Name  string `faker:"username"`
  Color string `faker:"color"` // Use custom color builder
}

type Person struct {
  FirstName string            `faker:"firstName"`         // Any available function case insensitive
  LastName  *string           `faker:"lastName"`          // Pointer are also supported
  Age       int               `faker:"intinrange(0,120)"` // Can call with parameters
  UUID      string            `faker:"uuid;unique"`       // Guarantees a unique value
  Number    int               `faker:"-"`                 // Skip this field
  Code      string            // No tag to use default builder for this field type
  Pet       Animal            // Recursively fill this struct
  Nicknames []string          `faker:"username;len=3"`          // Build an array of size 3 using faker.Username function
  Extra     map[string]string `faker:"stringWithSize(3);len=2"` // map are supported
}

p := Person{}
err = faker.Build(&p)
if err != nil {
  panic(err)
}
fmt.Println(p.FirstName)
fmt.Println(*p.LastName)
fmt.Println(p.Age)
fmt.Println(p.UUID)
fmt.Println(p.Number)
fmt.Println(p.Code)
fmt.Println(p.Pet.Name)
fmt.Println(p.Pet.Color)
fmt.Println(len(p.Nicknames))
fmt.Println(p.Nicknames[0])
fmt.Println(p.Nicknames[1])
fmt.Println(p.Nicknames[2])
fmt.Println(p.Extra)
// Output: Wilber
// Gutkowski
// 25
// ff8d6917-b920-46e6-b1be-dc2d48becfcb
// 0
// z
// honegger
// Red
// 3
// teagan
// polypeptide
// chinfest
// map[70w:3F6 gQS:isq]

Factory

One of the nice things about Faker is that it can also be used as a factory library. In fact when we call the faker.Build function if a value is not zero then it is not modified, leaving the original value. This allows you to create factory functions very easily:

faker.SetSeed(623)

type User struct {
    Username string `faker:"username"`
    Email    string `faker:"email"`
    Country  string `faker:"CountryAlpha2"`
}

italianUserFactory := func() *User {
    u := &User{Country: "IT"}
    faker.Build(u)
    return u
}

italianUser := italianUserFactory()
fmt.Println(italianUser)
// Output: &{spicule hoag@ornamented.biz IT}
Posted by:  Enrico