GitHub - Eun/go-convert: Convert a value into another type (original) (raw)

Convert a value into another type.

go get -u github.com/Eun/go-convert

Usage

package main

import ( "fmt"

"github.com/Eun/go-convert"

)

func main() { // convert a int to a string var s string convert.MustConvert(1, &s) fmt.Printf("%s\n", s)

// convert a map into a struct
type User struct {
    ID   int
    Name string
}
var u User
convert.MustConvert(map[string]string{
    "Name": "Joe",
    "ID":   "10",
}, &u)
fmt.Printf("%#v\n", u)

// convert Id to int and Groups to []int and keep the rest
m := map[string]interface{}{
    "Id":     0,
    "Groups": []int{},
}
// convert a map into well defined map
convert.MustConvert(
    map[string]interface{}{
        "Id":      "1",
        "Name":    "Joe",
        "Groups":  []string{"3", "6"},
        "Country": "US",
    },
    &m,
)
fmt.Printf("%v\n", m)

// convert a interface slice into well defined interface slice
// making the first one an integer, the second a string and the third an float
sl := []interface{}{0, "", 0.0}
convert.MustConvert([]string{"1", "2", "3"}, &sl)
fmt.Printf("%v\n", sl)

}

Recipe system

go-convert uses a recipe system that defines how and which types should be converted in which type. A lot of recipes are already builtin (see recipes.go), however you can add your own or overwrite the builtin ones.

package main

import ( "fmt" "strings"

"github.com/Eun/go-convert"

)

type Roles struct { IsAdmin bool IsDeveloper bool }

type User struct { ID int Name string Roles Roles }

func main() { // this is the data we want to convert data := map[string]string{ "id": "10", "Name": "Joe", "roles": "AD", // this user is Admin (A) and Developer (D) }

// create a converter
conv := convert.New(convert.Options{
    Recipes: convert.MustMakeRecipes(
        // convert string into Roles
        func(_ convert.Converter, in string, out *Roles) error {
            (*out).IsAdmin = false
            (*out).IsDeveloper = false
            if strings.Contains(in, "A") {
                (*out).IsAdmin = true
            }
            if strings.Contains(in, "D") {
                (*out).IsDeveloper = true
            }
            return nil
        },
    ),
})

var user User
conv.MustConvert(data, &user)
// user is now an instance of User
fmt.Printf("%#v\n", user)

}

Adding inline recipes

You can also add recipes inline by implementing a ConvertRecipes() []Recipe function.
Example:

package main

import ( "fmt" "strings"

"github.com/Eun/go-convert"

)

type Roles struct { IsAdmin bool IsDeveloper bool }

type User struct { ID int Name string Roles Roles }

func (user *User) ConvertRecipes() []convert.Recipe { return convert.MustMakeRecipes( // convert string into Roles func(_ convert.Converter, in string, out *Roles) error { out.IsAdmin = false out.IsDeveloper = false if strings.Contains(in, "A") { out.IsAdmin = true } if strings.Contains(in, "D") { out.IsDeveloper = true } return nil }, ) }

func main() { // this is the data we want to convert data := []map[string]string{ { "id": "10", "Name": "Joe", "roles": "AD", // this user is Admin (A) and Developer (D) }, { "id": "21", "Name": "Alice", "roles": "D", // this user is Developer (D) }, }

var users []User
convert.MustConvert(data, &users)
// users is now an instance of []User
fmt.Printf("%#v\n", users)

}

Notice

This library is using reflection so be aware it might be slow in your usecase.