go-convert

Convert a value into another type

Programming language: Go

License: MIT License

Tags: Utilities    

README

go-convert

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](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.