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。

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
// 对象转换
func Struct(params interface{}, objPointer interface{}, attrMapping ...map[string]string) error
// 类型名称转换
func Convert(i interface{}, t string, extraParams ...interface{}) interface{}

基本使用

使用示例：

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]

Struct转换

示例1，基本使用

package main
import (
    "fmt"
    "gitee.com/johng/gf/g"
    "gitee.com/johng/gf/g/util/gconv"
)
type User struct {
    Uid   int
    Name  string
    Pass1 string `gconv:"password1"`
    Pass2 string `gconv:"password2"`
}
func main() {
    user    := (*User)(nil)
    // 使用map直接映射绑定属性值到对象
    user     = new(User)
    params1 := g.Map{
        "uid"   : 1,
        "name"  : "john",
        "pass1" : "123",
        "pass2" : "123",
    }
    if err := gconv.Struct(params1, user); err == nil {
        fmt.Println(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",
        "password1" : "456",
        "password2" : "456",
    }
    if err := gconv.Struct(params2, user); err == nil {
        fmt.Println(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：

&{1 john 123 123}
&{2 smith 456 456}

示例2，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
    ]
}

示例3，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
    }
}

示例4，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
        }
    ]
}

示例5，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
        }
    ]
}