Faker
Random fake data and struct generator for Go.
- More than 100 generator functions
- Struct generator
- Unique data generator
- Builtin types support
- Easily customizable
- Zero dependencies
- Recursive infinite loop detector
- Benchmarks (coming soon)
Installation
go get github.com/pioz/faker
Example
faker.SetSeed(623)
fmt.Println(faker.Username())
fmt.Println(faker.String())
fmt.Println(faker.IntInRange(1, 10))
fmt.Println(faker.CurrencyName())
// Output: spicule
// gzaazJyRGt3jDnVh6ik7R9FO0AU1HcOzdOXbmNVBRQ5pq8n9tHf9B21PIFozLEzsoY4wILvZjTxSLQmD3UOAamDgVR411T3YHleDTgLuz90XSO3NFZm1AnaJiJamVRcNGD2zmi4qWkcjKF3E4JKgn1DiCeC3eSb5WELsw8XqRzlvJqG
// 10
// Myanmar Kyat
Please refer to the godoc for all available functions and more.
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 [email protected] IT}
Customization
A builder is a variadic function that will take an arbitrary number of strings as arguments and return an interface or an error. This function (builder) can be used to generate fake data and customize the behaviour of Faker. Here an example:
faker.SetSeed(1802)
// Define a new builder
builder := func(params ...string) (interface{}, error) {
if len(params) > 0 && params[0] == "melee" {
return faker.Pick("Barbarian", "Bard", "Fighter", "Monk", "Paladin", "Rogue"), nil
}
return faker.Pick("Cleric", "Druid", "Ranger", "Sorcerer", "Warlock", "Wizard"), nil
}
// Register a new builder named "dndClass" for string type
err := faker.RegisterBuilder("dndClass", "string", builder)
if err != nil {
panic(err)
}
player := &struct {
Class string `faker:"dndClass(melee)"`
// other fields ...
}{}
// Build a struct with fake data
faker.Build(&player)
fmt.Println(player.Class)
// Output: Paladin
Contributing with new generator functions
If you want to contribute to faker with new generator functions please read this wiki!
Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/pioz/faker/issues.
License
The package is available as open source under the terms of the MIT License.
