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defaults
========
[](https://circleci.com/gh/creasty/defaults/tree/master)
[](https://codecov.io/gh/creasty/defaults)
[](https://github.com/creasty/defaults/releases)
[](./LICENSE)
Initialize structs with default values
- Supports almost all kind of types
- Scalar types
- `int/8/16/32/64`, `uint/8/16/32/64`, `float32/64`
- `uintptr`, `bool`, `string`
- Complex types
- `map`, `slice`, `struct`
- Aliased types
- `time.Duration`
- e.g., `type Enum string`
- Pointer types
- e.g., `*SampleStruct`, `*int`
- Recursively initializes fields in a struct
- Dynamically sets default values by [`defaults.Setter`](./setter.go) interface
- Preserves non-initial values from being reset with a default value
Usage
-----
```go
type Gender string
type Sample struct {
Name string `default:"John Smith"`
Age int `default:"27"`
Gender Gender `default:"m"`
Slice []string `default:"[]"`
SliceByJSON []int `default:"[1, 2, 3]"` // Supports JSON
Map map[string]int `default:"{}"`
MapByJSON map[string]int `default:"{\"foo\": 123}"`
MapOfStruct map[string]OtherStruct
MapOfPtrStruct map[string]*OtherStruct
MapOfStructWithTag map[string]OtherStruct `default:"{\"Key1\": {\"Foo\":123}}"`
Struct OtherStruct `default:"{}"`
StructPtr *OtherStruct `default:"{\"Foo\": 123}"`
NoTag OtherStruct // Recurses into a nested struct by default
OptOut OtherStruct `default:"-"` // Opt-out
}
type OtherStruct struct {
Hello string `default:"world"` // Tags in a nested struct also work
Foo int `default:"-"`
Random int `default:"-"`
}
// SetDefaults implements defaults.Setter interface
func (s *OtherStruct) SetDefaults() {
if defaults.CanUpdate(s.Random) { // Check if it's a zero value (recommended)
s.Random = rand.Int() // Set a dynamic value
}
}
```
```go
obj := &Sample{}
if err := defaults.Set(obj); err != nil {
panic(err)
}
```
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