selective

Documentation

Overview

Package selective provides functionality to translate one struct type into another by selectively including fields with matching field tags.

Index

• func Encode(i interface{}, tag string) (interface{}, error)

Examples

• Encode

Functions

func Encode

func Encode(i interface{}, tag string) (interface{}, error)

Encode returns a value for an input struct value calculated by:

• If no fields non-empty "selective" tag values, the input is returned directly, retaining unexported fields and methods.

• Any field with a non-empty "selective" tag value is retained only if its tag contains the tag provided to Encode.

• Struct field values are calculated by calling this function on the input field's value with the same tag.

Returned values with changes (structs that contain at least one field with a non-empty "selective" tag) will lose unexported fields and methods. This is due to reflection being unable to retain them.

Example

package main

import (
	"encoding/json"
	"fmt"

	"github.com/splunk/go-splunk-client/pkg/selective"
)

type Discography struct {
	Albums  []string `json:"albums" selective:"albums"`
	Singles []string `json:"singles" selective:"singles"`
}

type Artist struct {
	// Name defines no selective tag, so it is always selected
	Name string `json:"name"`

	// Discography is selected for both albums and singles
	Discography Discography `json:"discography" selective:"albums,singles"`

	// Members is selected only for personnel
	Members []string `json:"members" selective:"personnel"`
}

func main() {
	artist := Artist{
		Name: "The Refreshments",
		Discography: Discography{
			Albums: []string{
				"Fizzy Fuzzy Big and Buzzy",
				"The Bottle and Fresh Horses",
			},
			Singles: []string{
				"Yahoos and Triangles",
			},
		},
		Members: []string{
			"Roger Clyne",
			"Dusty Denham",
			"P.H. Naffah",
			"Buddy Edwards",
			"Brian David Blush",
		},
	}

	artistAlbumsOnly, _ := selective.Encode(artist, "albums")
	artistAlbumsOnlyJSON, _ := json.MarshalIndent(artistAlbumsOnly, "", "  ")

	fmt.Printf("%s", artistAlbumsOnlyJSON)
}

Output:

{
  "name": "The Refreshments",
  "discography": {
    "albums": [
      "Fizzy Fuzzy Big and Buzzy",
      "The Bottle and Fresh Horses"
    ]
  }
}