如何在GoLang中创建单例数据库类

本文介绍了如何在GoLang中创建单例数据库类的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 如何创建单身人士，但我希望在那些方法，并称他们单身人士参考。我的代码如下： Mgr 是一个导出的全局变量，可以为其他包分配一个新的值（例如 dbprovider.Mgr = nil ）。如果你想避免这种情况，你必须使它不被导出，并为它提供一个getter函数，例如： var mgr = newManager（） func Mgr（）Manager {return mgr} err：= dbprovider.Mgr（）。AddArticle（someArticle） EDITED Solved:How should i create singleton DBManager class in GoLang.I Referred few code sample of how to create go singleton but i wish to have methods in those and call them on their singleton reference. My Code is as followspackage dbproviderimport ( "github.com/jinzhu/gorm" _"github.com/jinzhu/gorm/dialects/sqlite" "rest/article" "log")type DBOperations interface { AddArticle(article *article.Article)}type DBManager struct { db *gorm.DB isInitialized bool}var dbManagerInstance = new()func GetDBManager() DBManager { return dbManagerInstance}func new() DBManager { localDbRef, err := gorm.Open("sqlite3", "../articles.db") if (err != nil) { panic("Error initializing db") } else { log.Print("DB Initialized successfully") } return DBManager{db:localDbRef, isInitialized:true}}func (dbManager DBManager) AddArticle(article article.Article) (err error) { if (dbManager.isInitialized) { tx := dbManager.db.Begin() //dbManager.db.NewRecord(article) //dbManager.db.Commit() tx.NewRecord(article) tx.Commit() errs := dbManager.db.GetErrors() if (len(errs) > 0) { err = errs[0] } else { log.Print("No error in this transactions") } } return}With new answer i have updated this question including answer. But i have few queries. How to cathc and return exception from gorm.Create(..) 解决方案 One way is to create an exported interface with the methods, and make the implementing type unexported. Create a global variable of the interface type, and initialize it with a package init() function. You don't need any synchronization as the package init() function will run only once, safely.Package init() functions are executed once, automatically, by the runtime, before you could refer to anything from the package. For details, see Spec: Package initialization.For example:package dbprovidertype Manager interface { AddArticle(article *article.Article) error // Add other methods}type manager struct { db *gorm.DB}var Mgr Managerfunc init() { db, err := gorm.Open("sqlite3", "../articles.db") if err != nil { log.Fatal("Failed to init db:", err) } Mgr = &manager{db: db}}func (mgr *manager) AddArticle(article *article.Article) (err error) { mgr.db.Create(article) if errs := mgr.db.GetErrors(); len(errs) > 0 { err = errs[0] } return}Using it:import "dbprovider"if err := dbprovider.Mgr.AddArticle(someArticle); err != nil { // Handle error}You could also do it without an init() function, e.g.:var Mgr = newManager()func newManager() Manager { db, err := gorm.Open("sqlite3", "../articles.db") if err != nil { log.Fatal("Failed to init db:", err) } return &manager{db: db}}With this you may decide to make newManager() exported and users of your package could decide to use the shared Mgr instance, or they could create another Manager, e.g. for testing purposes.Notes: Mgr is an exported global variable, and it is possible to assign a new value to it by other packages (e.g. dbprovider.Mgr = nil). If you want to avoid this, you have to make it unexported, and provide a "getter" function for it, e.g.:var mgr = newManager()func Mgr() Manager { return mgr }And using it:err := dbprovider.Mgr().AddArticle(someArticle) 这篇关于如何在GoLang中创建单例数据库类的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！