README.md

ext_model

ext_model provides a small generic map container for business models.

This directory is an independent Go module.

Core Types

ExtObj

Any value stored in ExtMap must implement:

type ExtObj interface {
    Key() string
}

Key() is the only source of truth for the map key.

ExtModel[V ExtObj]

ExtModel is the behavior interface implemented by ExtMap.

type ExtModel[V ExtObj] interface {
    Get(key string) (V, bool)
    Set(value V)
    Del(key string) (V, bool)
    ForEach(fn func(value V))
}

ExtMap[V ExtObj]

ExtMap is a concurrency-safe container built on map[string]V.

Public methods:

• Set(value V)
• Get(key string) (V, bool)
• Del(key string) (V, bool)
• ForEach(fn func(value V))

Behavior

• The zero value of ExtMap is ready to use.
• Set always writes by value.Key().
• Get and Del operate by explicit string key.
• ForEach iterates over a snapshot of current values.
• Iteration order is not guaranteed.

Because ForEach uses a snapshot, calling Set or Del inside the callback will not break the current iteration.

Example: Attach Multiple Extension Structs to UserDO

The following example shows how to attach multiple extension records to one user object.

package main

import (
	"github.com/daidai21/biz_ext_framework/ext_model"
	"testing"
)

type userInfo struct {
	UserId int64
	ext_model.ExtModel
}

var (
	_ ext_model.ExtObj = userTaxInfo{}
	_ ext_model.ExtObj = userPhdInfo{}
)

type userTaxInfo struct {
	TaxId string
}

func (u userTaxInfo) Key() string {
	return "userTaxInfo"
}

type userPhdInfo struct {
	PhdId string
}

func (u userPhdInfo) Key() string {
	return "userPhdInfo"
}

func main(t *testing.T) {
	info := userInfo{
		UserId:   1,
		ExtModel: ext_model.NewExtModel(),
	}
	info.Set(userTaxInfo{TaxId: "tax_2313"})
	info.Set(userPhdInfo{PhdId: "phd_6748392"})
	t.Log(info)
	info.ForEach(func(value ext_model.ExtObj) {
		t.Log(value)
	})
}

Copy Utility

If you need to copy an ExtMap, use ext_model.CopyExtMap:

import "github.com/daidai21/biz_ext_framework/ext_model"

copied := ext_model.CopyExtMap(src)
filtered := ext_model.CopyExtMap(src, ext_model.WithKeyFilter[User](func(key string) bool {
    return key == "u1"
}))
deepCopied := ext_model.CopyExtMap(src, ext_model.WithDeepCopy[User](func(value User) User {
    return value
}))

Available options:

• WithDeepCopy
• WithKeyFilter