structer

Facilitates the loading of environment, and default values for a struct. The loading of these values happens in the order of environment variables first then default if empty. Data type defaults on struct properties if not strictly set will folow the associated data type. Configuration using the struct tag default:"myvalue" or env:"environment property name". A .env file is required for environment variables to work.

Reasons to use this library.

• Supports almost all kind of types
  • Scalar types
    • int/8/16/32/64, uint/8/16/32/64, float32/64
    • uintptr, bool, string
  • Complex types
    • map, slice, struct
  • Nested types
    • map[K1]map[K2]Struct, []map[K1]Struct[]
  • Aliased types
    • time.Duration
    • e.g., type Enum string
  • Pointer types
    • e.g., *SampleStruct, *int
• Recursively initializes fields in a struct
• Dynamically sets default values using [structer.Values.Set] method
• No instantiation is required.
• Preserves non-initial values from being reset with a default value

Installation

go get github.com/michaellanpart/structer@latest

Usage

// this code with associated env file are in ./example folder
package main

import (
	"github.com/joho/godotenv"
	"github.com/cranialfeed/structer"
)

func main() {

	// load environment variables
	godotenv.Load("./example/example.env")

	// instantiate struct
	user := &User{}

	// load env and default values
	structer.SetDefaults(user)

	// output object to console
	structer.PrettyPrint(user)
}

type Contact struct {
	Number string `json:"number"`
}
type User struct {
	ID               int       `default:"0" env:"EmployeeID" json:"id"`
	Name             string    `default:"" env:"EmployeeName" json:"name"`
	EmploymentStatus string    `default:"Employed" json:"employment_status"`
	Contacts         []Contact `default:"[{\"Number\":\"817-273-3746\"},{\"Number\":\"415-384-9919\"}]" json:"contacts"`
}

console output

{
    "id": 39438454,
    "name": "Roger Rabit",
    "employment_status": "Employed",
    "contacts": [
        {
            "number": "817-273-3746"
        },
        {
            "number": "415-384-9919"
        }
    ]
}