github.com/elastic/go-elasticsearch/_examples/encoding

Example: encoding

Examples in this folder demonstrate how to use helper methods and third-party packages for JSON decoding and encoding.

tidwall/gjson

The github.com/tidwall/gjson package allows an easy access to JSON properties, without parsing the payload into a data structure, and is therefore convenient when accessing only selected parts of the response.

var json = `{"foo":{"bar":"BAZ"}}`
fmt.Println(gjson.Get(json, "foo.bar"))
// => BAZ

The gjson.go example displays data from the Cluster Stats API.

go run gjson.go

mailru/easyjson

The github.com/mailru/easyjson package uses code generation to provide fast encoding and decoding of struct types.

The easyjson.go example uses custom types for representing simpleArticle documents and index and search responses, including error responses.

make clean setup
go run easyjson.go

esutil.JSONReader()

The esutil.JSONReader() helper method takes a struct, a map, or any other serializable object, and converts it to JSON wrapped in a reader, for convenient passing to the WithBody() methods:

type Document struct{ Title string }
doc := Document{Title: "Test"}
es.Search(es.Search.WithBody(esutil.NewJSONReader(&doc)))

Benchmarks

Both mailru/easyjson and tidwall/gjson provide significant performance gains in different scenarios.

You can run the included benchmarks by executing the make bench command; example output below.

BenchmarkEncode/Article_-_json         	  500000	      2969 ns/op	     856 B/op	       8 allocs/op
BenchmarkEncode/Article_-_JSONReader   	  500000	      2957 ns/op	     920 B/op	      10 allocs/op
BenchmarkEncode/Article_-_easyjson     	 1000000	      1089 ns/op	     736 B/op	       5 allocs/op
BenchmarkEncode/map_-_json             	 1000000	      2074 ns/op	     720 B/op	      18 allocs/op
BenchmarkEncode/map_-_JSONReader       	 1000000	      2168 ns/op	     784 B/op	      20 allocs/op

BenchmarkDecode/Search_-_json          	   50000	     38922 ns/op	    8456 B/op	      60 allocs/op
BenchmarkDecode/Search_-_easyjson      	  100000	     14344 ns/op	    7992 B/op	      52 allocs/op
BenchmarkDecode/Cluster_-_json_-_map   	   20000	     85742 ns/op	   31972 B/op	     391 allocs/op
BenchmarkDecode/Cluster_-_json_-_stc   	   30000	     50852 ns/op	   15048 B/op	      17 allocs/op
BenchmarkDecode/Cluster_-_gjson        	 1000000	      2284 ns/op	     264 B/op	       3 allocs/op