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gf框架提供了非常强大的类型转换包gconv,可以实现将任何数据类型转换为指定的数据类型,对常用基本数据类型之间的无缝转换,同时也支持任意类型到struct对象的属性赋值。由于gconv模块内部大量使用了断言而非反射(仅struct转换使用到了反射),因此执行的效率非常高。

使用方式:

import "gitee.com/johng/gf/g/util/gconv"

方法列表: godoc.org/github.com/johng-cn/gf/g/util/gconv

// 基本类型
func Bool(i interface{}) bool
func Float32(i interface{}) float32
func Float64(i interface{}) float64
func Int(i interface{}) int
func Int16(i interface{}) int16
func Int32(i interface{}) int32
func Int64(i interface{}) int64
func Int8(i interface{}) int8
func String(i interface{}) string
func Uint(i interface{}) uint
func Uint16(i interface{}) uint16
func Uint32(i interface{}) uint32
func Uint64(i interface{}) uint64
func Uint8(i interface{}) uint8

// slice类型
func Bytes(i interface{}) []byte
func Ints(i interface{}) []int
func Floats(i interface{}) []float64
func Strings(i interface{}) []string
func Interfaces(i interface{}) []interface{}

// 时间类型
func Time(i interface{}, format ...string) time.Time
func TimeDuration(i interface{}) time.Duration

// Map转换, 支持的类型包括:任意map或struct
func Map(i interface{}, noTagCheck...bool) map[string]interface{}

// 对象转换
func Struct(params interface{}, objPointer interface{}, attrMapping ...map[string]string) error

// 根据类型名称执行基本类型转换(非struct转换))
func Convert(i interface{}, t string, extraParams ...interface{}) interface{}

基本使用

常用基本类型的转换方法比较简单,我们这里使用一个例子来演示转换方法的使用及效果。

package main

import (
    "fmt"
    "gitee.com/johng/gf/g/util/gconv"
)

func main() {
    i := 123
    fmt.Printf("%10s %v\n", "Int:",        gconv.Int(i))
    fmt.Printf("%10s %v\n", "Int8:",       gconv.Int8(i))
    fmt.Printf("%10s %v\n", "Int16:",      gconv.Int16(i))
    fmt.Printf("%10s %v\n", "Int32:",      gconv.Int32(i))
    fmt.Printf("%10s %v\n", "Int64:",      gconv.Int64(i))
    fmt.Printf("%10s %v\n", "Uint:",       gconv.Uint(i))
    fmt.Printf("%10s %v\n", "Uint8:",      gconv.Uint8(i))
    fmt.Printf("%10s %v\n", "Uint16:",     gconv.Uint16(i))
    fmt.Printf("%10s %v\n", "Uint32:",     gconv.Uint32(i))
    fmt.Printf("%10s %v\n", "Uint64:",     gconv.Uint64(i))
    fmt.Printf("%10s %v\n", "Float32:",    gconv.Float32(i))
    fmt.Printf("%10s %v\n", "Float64:",    gconv.Float64(i))
    fmt.Printf("%10s %v\n", "Bool:",       gconv.Bool(i))
    fmt.Printf("%10s %v\n", "String:",     gconv.String(i))

    fmt.Printf("%10s %v\n", "Bytes:",      gconv.Bytes(i))
    fmt.Printf("%10s %v\n", "Strings:",    gconv.Strings(i))
    fmt.Printf("%10s %v\n", "Ints:",       gconv.Ints(i))
    fmt.Printf("%10s %v\n", "Floats:",     gconv.Floats(i))
    fmt.Printf("%10s %v\n", "Interfaces:", gconv.Interfaces(i))
}

执行后,输出结果为:

      Int: 123
     Int8: 123
    Int16: 123
    Int32: 123
    Int64: 123
     Uint: 123
    Uint8: 123
   Uint16: 123
   Uint32: 123
   Uint64: 123
  Float32: 123
  Float64: 123
     Bool: true
   String: 123
    Bytes: [123]
  Strings: [123]
     Ints: [123]
   Floats: [123]
Interfaces: [123]

Map转换

gconv.Map支持将任意的mapstruct类型转换为 map[string]interface{} 类型,需要注意的是当转换struct类型时,支持自动识别struct的json tag,但是可以通过Map方法的第二个参数noTagCheck进行忽略。 如果转换失败,返回nil

// Map转换, 支持的类型包括:任意map或struct
func Map(i interface{}, noTagCheck...bool) map[string]interface{}

使用示例:

package main

import (
    "fmt"
    "gitee.com/johng/gf/g/util/gconv"
)

func main() {
    type User struct {
        Uid  int    `json:"uid"`
        Name string `json:"name"`
    }
    // 对象
    fmt.Println(gconv.Map(User{
        Uid      : 1,
        Name     : "john",
    }))
    // 对象指针
    fmt.Println(gconv.Map(&User{
        Uid      : 1,
        Name     : "john",
    }))

    // 任意map类型
    fmt.Println(gconv.Map(map[int]int{
        100 : 10000,
    }))
}

执行后,输出结果如下:

map[uid:1 name:john]
map[uid:1 name:john]
map[100:10000]

Struct转换

项目中我们经常会遇到大量struct的使用,以及各种数据类型到struct的转换/赋值(特别是json/xml/各种协议编码转换的时候)。为提高编码及项目维护效率,gconv模块为各位开发者带来了极大的福利,为数据解析提供了更高的灵活度。

gconv模块执行struct转换的方法仅有一个,定义如下:

func Struct(params interface{}, objPointer interface{}, attrMapping ...map[string]string) error

其中: 1. params为需要转换到struct的变量参数,可以为任意数据类型,常见的数据类型为map; 1. objPointer为需要执行转的目标struct对象,这个参数必须为该struct的对象指针,转换成功后该对象的属性将会更新; 1. attrMapping为自定义的map键名strcut属性之间的映射关系,此时params参数必须为map类型,否则该参数无意义;

转换规则

gconv模块的struct转换特性非常强大,支持任意数据类型到struct属性的映射转换。在没有提供自定义attrMapping转换规则的情况下,默认的转换规则如下: 1. struct中需要匹配的属性必须为公开属性(首字母大写); 2. 根据params类型的不同,逻辑会有不同: - params参数为map: 键名会自动按照 不区分大小写忽略-/_/空格符号 的形式与struct属性进行匹配; - params参数为其他类型: 将会把该变量值与struct的第一个属性进行匹配; - 此外,如果struct的属性为复杂数据类型如slice,map,strcut那么会进行递归匹配赋值; 3. 如果匹配成功,那么将键值赋值给属性,如果无法匹配,那么忽略;

以下是几个匹配的示例:

map键名    struct属性     是否匹配
name       Name           match
Email      Email          match
nickname   NickName       match
NICKNAME   NickName       match
Nick-Name  NickName       match
nick_name  NickName       match
nick name  NickName       match
NickName   Nick_Name      match
Nick-name  Nick_Name      match
nick_name  Nick_Name      match
nick name  Nick_Name      match

示例1,基本使用

package main

import (
    "gitee.com/johng/gf/g"
    "gitee.com/johng/gf/g/util/gconv"
)

type User struct {
    Uid      int
    Name     string
    Site_Url string
    NickName string
    Pass1    string `gconv:"password1"`
    Pass2    string `gconv:"password2"`
}

func main() {
    user    := (*User)(nil)

    // 使用默认映射规则绑定属性值到对象
    user     = new(User)
    params1 := g.Map{
        "uid"       : 1,
        "Name"      : "john",
        "siteurl"   : "https://gfer.me",
        "nick_name" : "johng",
        "PASS1"     : "123",
        "PASS2"     : "456",
    }
    if err := gconv.Struct(params1, user); err == nil {
        g.Dump(user)
    }

    // 使用struct tag映射绑定属性值到对象
    user     = new(User)
    params2 := g.Map {
        "uid"       : 2,
        "name"      : "smith",
        "site-url"  : "https://gfer.me",
        "nick name" : "johng",
        "password1" : "111",
        "password2" : "222",
    }
    if err := gconv.Struct(params2, user); err == nil {
        g.Dump(user)
    }
}

可以看到,我们可以直接通过Struct方法将map按照默认规则绑定到struct上,也可以使用struct tag的方式进行灵活的设置。此外,Struct方法有第三个map参数,用于指定自定义的参数名称到属性名称的映射关系。

执行后,输出结果为:

{
	"Uid": 1,
	"Name": "john",
	"Site_Url": "https://gfer.me",
	"NickName": "johng",
	"Pass1": "123",
	"Pass2": "456"
}
{
	"Uid": 2,
	"Name": "smith",
	"Site_Url": "https://gfer.me",
	"NickName": "johng",
	"Pass1": "111",
	"Pass2": "222"
}

示例2,复杂类型转换

1. slice基本类型属性

package main

import (
    "gitee.com/johng/gf/g/util/gconv"
    "gitee.com/johng/gf/g"
    "fmt"
)

// 演示slice类型属性的赋值
func main() {
    type User struct {
        Scores []int
    }

    user   := new(User)
    scores := []interface{}{99, 100, 60, 140}

    // 通过map映射转换
    if err := gconv.Struct(g.Map{"Scores" : scores}, user); err != nil {
        fmt.Println(err)
    } else {
        g.Dump(user)
    }

    // 通过变量映射转换,直接slice赋值
    if err := gconv.Struct(scores, user); err != nil {
        fmt.Println(err)
    } else {
        g.Dump(user)
    }
}

执行后,输出结果为:

{
	"Scores": [
		99,
		100,
		60,
		140
	]
}
{
	"Scores": [
		99,
		100,
		60,
		140
	]
}

2. struct属性为struct

package main

import (
    "gitee.com/johng/gf/g/util/gconv"
    "gitee.com/johng/gf/g"
    "fmt"
)

func main() {
    type Score struct {
        Name   string
        Result int
    }
    type User struct {
        Scores Score
    }

    user   := new(User)
    scores := map[string]interface{}{
        "Scores" : map[string]interface{}{
            "Name"   : "john",
            "Result" : 100,
        },
    }

    // 嵌套struct转换
    if err := gconv.Struct(scores, user); err != nil {
        fmt.Println(err)
    } else {
        g.Dump(user)
    }
}

执行后,输出结果为:

{
	"Scores": {
		"Name": "john",
		"Result": 100
	}
}

3. struct属性为slice,数值为slice

package main

import (
    "gitee.com/johng/gf/g/util/gconv"
    "gitee.com/johng/gf/g"
    "fmt"
)

func main() {
    type Score struct {
        Name   string
        Result int
    }
    type User struct {
        Scores []Score
    }

    user   := new(User)
    scores := map[string]interface{}{
        "Scores" : []interface{}{
            map[string]interface{}{
                "Name"   : "john",
                "Result" : 100,
            },
            map[string]interface{}{
                "Name"   : "smith",
                "Result" : 60,
            },
        },
    }

    // 嵌套struct转换,属性为slice类型,数值为slice map类型
    if err := gconv.Struct(scores, user); err != nil {
        fmt.Println(err)
    } else {
        g.Dump(user)
    }
}

执行后,输出结果为:

{
	"Scores": [
		{
			"Name": "john",
			"Result": 100
		},
		{
			"Name": "smith",
			"Result": 60
		}
	]
}

4. struct属性为slice,数值为非slice

package main

import (
    "gitee.com/johng/gf/g/util/gconv"
    "gitee.com/johng/gf/g"
    "fmt"
)

func main() {
    type Score struct {
        Name   string
        Result int
    }
    type User struct {
        Scores []Score
    }

    user   := new(User)
    scores := map[string]interface{}{
        "Scores" : map[string]interface{}{
            "Name"   : "john",
            "Result" : 100,
        },
    }

    // 嵌套struct转换,属性为slice类型,数值为map类型
    if err := gconv.Struct(scores, user); err != nil {
        fmt.Println(err)
    } else {
        g.Dump(user)
    }
}

执行后,输出结果为:

{
	"Scores": [
		{
			"Name": "john",
			"Result": 100
		}
	]
}

基准性能测试

测试转换变量值为123456789,类型int

john@john-B85M:~/Workspace/Go/GOPATH/src/gitee.com/johng/gf/g/util/gconv$ go test *.go -bench=".*" -benchmem
goos: linux
goarch: amd64
BenchmarkString-4               20000000                71.8 ns/op            24 B/op          2 allocs/op
BenchmarkInt-4                  100000000               22.2 ns/op             8 B/op          1 allocs/op
BenchmarkInt8-4                 100000000               24.5 ns/op             8 B/op          1 allocs/op
BenchmarkInt16-4                50000000                23.8 ns/op             8 B/op          1 allocs/op
BenchmarkInt32-4                100000000               24.1 ns/op             8 B/op          1 allocs/op
BenchmarkInt64-4                100000000               21.7 ns/op             8 B/op          1 allocs/op
BenchmarkUint-4                 100000000               22.2 ns/op             8 B/op          1 allocs/op
BenchmarkUint8-4                50000000                25.6 ns/op             8 B/op          1 allocs/op
BenchmarkUint16-4               50000000                32.1 ns/op             8 B/op          1 allocs/op
BenchmarkUint32-4               50000000                27.7 ns/op             8 B/op          1 allocs/op
BenchmarkUint64-4               50000000                28.1 ns/op             8 B/op          1 allocs/op
BenchmarkFloat32-4              10000000               155 ns/op              24 B/op          2 allocs/op
BenchmarkFloat64-4              10000000               177 ns/op              24 B/op          2 allocs/op
BenchmarkTime-4                  5000000               240 ns/op              72 B/op          4 allocs/op
BenchmarkTimeDuration-4         50000000                26.2 ns/op             8 B/op          1 allocs/op
BenchmarkBytes-4                10000000               149 ns/op             128 B/op          3 allocs/op
BenchmarkStrings-4              10000000               223 ns/op              40 B/op          3 allocs/op
BenchmarkInts-4                 20000000                55.0 ns/op            16 B/op          2 allocs/op
BenchmarkFloats-4               10000000               186 ns/op              32 B/op          3 allocs/op
BenchmarkInterfaces-4           20000000                66.6 ns/op            24 B/op          2 allocs/op
PASS
ok      command-line-arguments  35.356s