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package mapstructure

import (

"fmt"

)

func ExampleDecode() {

type Person struct {

Name string

Age int

Emails []string

Extra map[string]string

}

// This input can come from anywhere, but typically comes from

// something like decoding JSON where we're not quite sure of the

// struct initially.

input := map[string]interface{}{

"name": "Mitchell",

"age": 91,

"emails": []string{"one", "two", "three"},

"extra": map[string]string{

"twitter": "mitchellh",

},

}

var result Person

err := Decode(input, &result)

if err != nil {

panic(err)

}

fmt.Printf("%#v", result)

// Output:

// mapstructure.Person{Name:"Mitchell", Age:91, Emails:[]string{"one", "two", "three"}, Extra:map[string]string{"twitter":"mitchellh"}}

}

func ExampleDecode_errors() {

type Person struct {

Name string

Age int

Emails []string

Extra map[string]string

}

// This input can come from anywhere, but typically comes from

// something like decoding JSON where we're not quite sure of the

// struct initially.

input := map[string]interface{}{

"name": 123,

"age": "bad value",

"emails": []int{1, 2, 3},

}

var result Person

err := Decode(input, &result)

if err == nil {

panic("should have an error")

}

fmt.Println(err.Error())

// Output:

// 5 error(s) decoding:

//

// * 'Age' expected type 'int', got unconvertible type 'string', value: 'bad value'

// * 'Emails[0]' expected type 'string', got unconvertible type 'int', value: '1'

// * 'Emails[1]' expected type 'string', got unconvertible type 'int', value: '2'

// * 'Emails[2]' expected type 'string', got unconvertible type 'int', value: '3'

// * 'Name' expected type 'string', got unconvertible type 'int', value: '123'

}

func ExampleDecode_metadata() {

type Person struct {

Name string

Age int

}

// This input can come from anywhere, but typically comes from

// something like decoding JSON where we're not quite sure of the

// struct initially.

input := map[string]interface{}{

"name": "Mitchell",

"age": 91,

"email": "foo@bar.com",

}

// For metadata, we make a more advanced DecoderConfig so we can

// more finely configure the decoder that is used. In this case, we

// just tell the decoder we want to track metadata.

var md Metadata

var result Person

config := &DecoderConfig{

Metadata: &md,

Result: &result,

}

decoder, err := NewDecoder(config)

if err != nil {

panic(err)

}

if err := decoder.Decode(input); err != nil {

panic(err)

}

fmt.Printf("Unused keys: %#v", md.Unused)

// Output:

// Unused keys: []string{"email"}

}

func ExampleDecode_weaklyTypedInput() {

type Person struct {

Name string

Age int

Emails []string

}

// This input can come from anywhere, but typically comes from

// something like decoding JSON, generated by a weakly typed language

// such as PHP.

input := map[string]interface{}{

"name": 123, // number => string

"age": "42", // string => number

"emails": map[string]interface{}{}, // empty map => empty array

}

var result Person

config := &DecoderConfig{

WeaklyTypedInput: true,

Result: &result,

}

decoder, err := NewDecoder(config)

if err != nil {

panic(err)

}

err = decoder.Decode(input)

if err != nil {

panic(err)

}

fmt.Printf("%#v", result)

// Output: mapstructure.Person{Name:"123", Age:42, Emails:[]string{}}

}

func ExampleDecode_tags() {

// Note that the mapstructure tags defined in the struct type

// can indicate which fields the values are mapped to.

type Person struct {

Name string `mapstructure:"person_name"`

Age int `mapstructure:"person_age"`

}

input := map[string]interface{}{

"person_name": "Mitchell",

"person_age": 91,

}

var result Person

err := Decode(input, &result)

if err != nil {

panic(err)

}

fmt.Printf("%#v", result)

// Output:

// mapstructure.Person{Name:"Mitchell", Age:91}

}

func ExampleDecode_embeddedStruct() {

// Squashing multiple embedded structs is allowed using the squash tag.

// This is demonstrated by creating a composite struct of multiple types

// and decoding into it. In this case, a person can carry with it both

// a Family and a Location, as well as their own FirstName.

type Family struct {

LastName string

}

type Location struct {

City string

}

type Person struct {

Family `mapstructure:",squash"`

Location `mapstructure:",squash"`

FirstName string

}

input := map[string]interface{}{

"FirstName": "Mitchell",

"LastName": "Hashimoto",

"City": "San Francisco",

}

var result Person

err := Decode(input, &result)

if err != nil {

panic(err)

}

fmt.Printf("%s %s, %s", result.FirstName, result.LastName, result.City)

// Output:

// Mitchell Hashimoto, San Francisco

}

func ExampleDecode_remainingData() {

// Note that the mapstructure tags defined in the struct type

// can indicate which fields the values are mapped to.

type Person struct {

Name string

Age int

Other map[string]interface{} `mapstructure:",remain"`

}

input := map[string]interface{}{

"name": "Mitchell",

"age": 91,

"email": "mitchell@example.com",

}

var result Person

err := Decode(input, &result)

if err != nil {

panic(err)

}

fmt.Printf("%#v", result)

// Output:

// mapstructure.Person{Name:"Mitchell", Age:91, Other:map[string]interface {}{"email":"mitchell@example.com"}}

}

func ExampleDecode_omitempty() {

// Add omitempty annotation to avoid map keys for empty values

type Family struct {

LastName string

}

type Location struct {

City string

}

type Person struct {

*Family `mapstructure:",omitempty"`

*Location `mapstructure:",omitempty"`

Age int

FirstName string

}

result := &map[string]interface{}{}

input := Person{FirstName: "Somebody"}

err := Decode(input, &result)

if err != nil {

panic(err)

}

fmt.Printf("%+v", result)

// Output:

// &map[Age:0 FirstName:Somebody]

}