Golang dynamic struct

Package dynamic struct provides possibility to dynamically, in runtime, extend or merge existing defined structs or to provide completely new struct.

Main features:

Building completely new struct in runtime
Extending existing struct in runtime
Merging multiple structs in runtime
Adding new fields into struct
Removing existing fields from struct
Modifying fields' types and tags
Easy reading of dynamic structs
Mapping dynamic struct with set values to existing struct
Make slices and maps of dynamic structs

Works out-of-the-box with:

Benchmarks

Environment:

MacBook Pro (13-inch, Early 2015), 2,7 GHz Intel Core i5
go version go1.11 darwin/amd64

goos: darwin
goarch: amd64
pkg: github.com/ompluscator/dynamic-struct
BenchmarkClassicWay_NewInstance-4                 2000000000     0.34 ns/op
BenchmarkNewStruct_NewInstance-4                    10000000      141 ns/op
BenchmarkNewStruct_NewInstance_Parallel-4           20000000     89.6 ns/op
BenchmarkExtendStruct_NewInstance-4                 10000000      135 ns/op
BenchmarkExtendStruct_NewInstance_Parallel-4        20000000     89.5 ns/op
BenchmarkMergeStructs_NewInstance-4                 10000000      140 ns/op
BenchmarkMergeStructs_NewInstance_Parallel-4        20000000     94.3 ns/op

Add new struct

package main

import (
	"encoding/json"
	"fmt"
	"log"

	"github.com/ompluscator/dynamic-struct"
)

func main() {
	instance := dynamicstruct.NewStruct().
		AddField("Integer", 0, `json:"int"`).
		AddField("Text", "", `json:"someText"`).
		AddField("Float", 0.0, `json:"double"`).
		AddField("Boolean", false, "").
		AddField("Slice", []int{}, "").
		AddField("Anonymous", "", `json:"-"`).
		Build().
		New()

	data := []byte(`
{
    "int": 123,
    "someText": "example",
    "double": 123.45,
    "Boolean": true,
    "Slice": [1, 2, 3],
    "Anonymous": "avoid to read"
}
`)

	err := json.Unmarshal(data, &instance)
	if err != nil {
		log.Fatal(err)
	}

	data, err = json.Marshal(instance)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println(string(data))
	// Out:
	// {"int":123,"someText":"example","double":123.45,"Boolean":true,"Slice":[1,2,3]}
}

Extend existing struct

package main

import (
	"encoding/json"
	"fmt"
	"log"

	"github.com/ompluscator/dynamic-struct"
)

type Data struct {
	Integer int `json:"int"`
}

func main() {
	instance := dynamicstruct.ExtendStruct(Data{}).
		AddField("Text", "", `json:"someText"`).
		AddField("Float", 0.0, `json:"double"`).
		AddField("Boolean", false, "").
		AddField("Slice", []int{}, "").
		AddField("Anonymous", "", `json:"-"`).
		Build().
		New()

	data := []byte(`
{
    "int": 123,
    "someText": "example",
    "double": 123.45,
    "Boolean": true,
    "Slice": [1, 2, 3],
    "Anonymous": "avoid to read"
}
`)

	err := json.Unmarshal(data, &instance)
	if err != nil {
		log.Fatal(err)
	}

	data, err = json.Marshal(instance)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println(string(data))
	// Out:
	// {"int":123,"someText":"example","double":123.45,"Boolean":true,"Slice":[1,2,3]}
}

Merge existing structs

package main

import (
	"encoding/json"
	"fmt"
	"log"

	"github.com/ompluscator/dynamic-struct"
)

type DataOne struct {
	Integer int     `json:"int"`
	Text    string  `json:"someText"`
	Float   float64 `json:"double"`
}

type DataTwo struct {
	Boolean bool
	Slice []int
	Anonymous string `json:"-"`
}

func main() {
	instance := dynamicstruct.MergeStructs(DataOne{}, DataTwo{}).
		Build().
		New()

	data := []byte(`
{
"int": 123,
"someText": "example",
"double": 123.45,
"Boolean": true,
"Slice": [1, 2, 3],
"Anonymous": "avoid to read"
}
`)

	err := json.Unmarshal(data, &instance)
	if err != nil {
		log.Fatal(err)
	}

	data, err = json.Marshal(instance)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println(string(data))
	// Out:
	// {"int":123,"someText":"example","double":123.45,"Boolean":true,"Slice":[1,2,3]}
}

Read dynamic struct

package main

import (
	"encoding/json"
	"fmt"
	"log"

	"github.com/ompluscator/dynamic-struct"
)

type DataOne struct {
	Integer int     `json:"int"`
	Text    string  `json:"someText"`
	Float   float64 `json:"double"`
}

type DataTwo struct {
	Boolean bool
	Slice []int
	Anonymous string `json:"-"`
}

func main() {
	instance := dynamicstruct.MergeStructs(DataOne{}, DataTwo{}).
		Build().
		New()

	data := []byte(`
{
"int": 123,
"someText": "example",
"double": 123.45,
"Boolean": true,
"Slice": [1, 2, 3],
"Anonymous": "avoid to read"
}
`)

	err := json.Unmarshal(data, &instance)
	if err != nil {
		log.Fatal(err)
	}

	reader := dynamicstruct.NewReader(instance)

	fmt.Println("Integer", reader.GetField("Integer").Int())
	fmt.Println("Text", reader.GetField("Text").String())
	fmt.Println("Float", reader.GetField("Float").Float64())
	fmt.Println("Boolean", reader.GetField("Boolean").Bool())
	fmt.Println("Slice", reader.GetField("Slice").Interface().([]int))
	fmt.Println("Anonymous", reader.GetField("Anonymous").String())

	var dataOne DataOne
	err = reader.ToStruct(&dataOne)
	fmt.Println(err, dataOne)

	var dataTwo DataTwo
	err = reader.ToStruct(&dataTwo)
	fmt.Println(err, dataTwo)
	// Out:
	// Integer 123
	// Text example
	// Float 123.45
	// Boolean true
	// Slice [1 2 3]
	// Anonymous
	// <nil> {123 example 123.45}
	// <nil> {true [1 2 3] }
}

Make a slice of dynamic struct

package main

import (
	"encoding/json"
	"fmt"
	"log"

	"github.com/ompluscator/dynamic-struct"
)

type Data struct {
	Integer   int     `json:"int"`
	Text      string  `json:"someText"`
	Float     float64 `json:"double"`
	Boolean   bool
	Slice     []int
	Anonymous string `json:"-"`
}

func main() {
	definition := dynamicstruct.ExtendStruct(Data{}).Build()

	slice := definition.NewSliceOfStructs()

	data := []byte(`
[
	{
		"int": 123,
		"someText": "example",
		"double": 123.45,
		"Boolean": true,
		"Slice": [1, 2, 3],
		"Anonymous": "avoid to read"
	}
]
`)

	err := json.Unmarshal(data, &slice)
	if err != nil {
		log.Fatal(err)
	}

	data, err = json.Marshal(slice)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println(string(data))
	// Out:
	// [{"Boolean":true,"Slice":[1,2,3],"int":123,"someText":"example","double":123.45}]

	reader := dynamicstruct.NewReader(slice)
	readersSlice := reader.ToSliceOfReaders()
	for k, v := range readersSlice {
		var value Data
		err := v.ToStruct(&value)
		if err != nil {
			log.Fatal(err)
		}

		fmt.Println(k, value)
	}
	// Out:
	// 0 {123 example 123.45 true [1 2 3] }
}

Make a map of dynamic struct

package main

import (
	"encoding/json"
	"fmt"
	"log"

	"github.com/ompluscator/dynamic-struct"
)

type Data struct {
	Integer   int     `json:"int"`
	Text      string  `json:"someText"`
	Float     float64 `json:"double"`
	Boolean   bool
	Slice     []int
	Anonymous string `json:"-"`
}

func main() {
	definition := dynamicstruct.ExtendStruct(Data{}).Build()

	mapWithStringKey := definition.NewMapOfStructs("")

	data := []byte(`
{
	"element": {
		"int": 123,
		"someText": "example",
		"double": 123.45,
		"Boolean": true,
		"Slice": [1, 2, 3],
		"Anonymous": "avoid to read"
	}
}
`)

	err := json.Unmarshal(data, &mapWithStringKey)
	if err != nil {
		log.Fatal(err)
	}

	data, err = json.Marshal(mapWithStringKey)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println(string(data))
	// Out:
	// {"element":{"int":123,"someText":"example","double":123.45,"Boolean":true,"Slice":[1,2,3]}}

	reader := dynamicstruct.NewReader(mapWithStringKey)
	readersMap := reader.ToMapReaderOfReaders()
	for k, v := range readersMap {
		var value Data
		err := v.ToStruct(&value)
		if err != nil {
			log.Fatal(err)
		}

		fmt.Println(k, value)
	}
	// Out:
	// element {123 example 123.45 true [1 2 3] }
}

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