# 08-Follower 这章将告诉你如何实现类似于Twitter和其他社交网络的“粉丝”功能。 在本章中，我将更多地使用应用的数据库。 我希望应用的用户能够轻松便捷地关注其他用户。 *本章的GitHub链接为：* [Source](https://github.com/bonfy/go-mega-code/tree/08-Follower), [Diff](https://github.com/bonfy/go-mega-code/compare/07-Profile-Page...08-Follower), [Zip](https://github.com/bonfy/go-mega-code/archive/v0.8.zip) ## 完善用户模型 首先我们列下要实现的用户操作: * 关注 - Follow * 取消关注 - UnFollow * 关注自己 - FollowSelf * follower数量 - FollowersCount * following数量 - FollowingCount * 关注的Posts - FollowingPosts 这个将被用在页面美化那章中的登陆后的IndexView显示 * 判断是否被关注 - IsFollowedByUser * (\*)创建Post - CreatePost 这个是我们为了方便创建数据加入的，和粉丝操作关系不大 > Tip: 这里 Followers 可以通过 Gorm 的 `Association("Followers")`来实现， Following 好像不支持(不确定，看了几遍文档没有找到)，不过这里我们一顿骚操作，自己来实现一下嘛 model/user.go ```go ... // Follow func // follow someone usr_id other.id follow_id u.id func (u *User) Follow(username string) error { other, err := GetUserByUsername(username) if err != nil { return err } return db.Model(other).Association("Followers").Append(u).Error } // Unfollow func func (u *User) Unfollow(username string) error { other, err := GetUserByUsername(username) if err != nil { return err } return db.Model(other).Association("Followers").Delete(u).Error } // FollowSelf func func (u *User) FollowSelf() error { return db.Model(u).Association("Followers").Append(u).Error } // FollowersCount func func (u *User) FollowersCount() int { return db.Model(u).Association("Followers").Count() } // FollowingIDs func func (u *User) FollowingIDs() []int { var ids []int rows, err := db.Table("follower").Where("follower_id = ?", u.ID).Select("user_id, follower_id").Rows() if err != nil { log.Println("Counting Following error:", err) return ids } defer rows.Close() for rows.Next() { var id, followerID int rows.Scan(&id, &followerID) ids = append(ids, id) } return ids } // FollowingCount func func (u *User) FollowingCount() int { ids := u.FollowingIDs() return len(ids) } // FollowingPosts func func (u *User) FollowingPosts() (*[]Post, error) { var posts []Post ids := u.FollowingIDs() if err := db.Preload("User").Order("timestamp desc").Where("user_id in (?)", ids).Find(&posts).Error; err != nil { return nil, err } return &posts, nil } // IsFollowedByUser func func (u *User) IsFollowedByUser(username string) bool { user, _ := GetUserByUsername(username) ids := user.FollowingIDs() for _, id := range ids { if u.ID == id { return true } } return false } // CreatePost func func (u *User) CreatePost(body string) error { post := Post{Body: body, UserID: u.ID} return db.Create(&post).Error } ... ``` 然后在 AddUser 的时候加入 FollowSelf, 即自己关注自己，方便在显示 Profile 页的时候，展示 FollowingPosts 将自己的 Post 也列进去 model/user.go ```go // AddUser func func AddUser(username, password, email string) error { user := User{Username: username, Email: email} user.SetPassword(password) user.SetAvatar(email) if err := db.Create(&user).Error; err != nil { return err } return user.FollowSelf() } ``` 由于我们一开始的建立用户，没有加入 Follower 功能，我们重新初始化一遍数据 cmd/init\_db\main.go ```go package main import ( "log" "github.com/bonfy/go-mega-code/model" _ "github.com/jinzhu/gorm/dialects/mysql" ) func main() { log.Println("DB Init ...") db := model.ConnectToDB() defer db.Close() model.SetDB(db) db.DropTableIfExists(model.User{}, model.Post{}, "follower") db.CreateTable(model.User{}, model.Post{}) model.AddUser("bonfy", "abc123", "i@bonfy.im") model.AddUser("rene", "abc123", "rene@test.com") u1, _ := model.GetUserByUsername("bonfy") u1.CreatePost("Beautiful day in Portland!") model.UpdateAboutMe(u1.Username, `I'm the author of Go-Mega Tutorial you are reading now!`) u2, _ := model.GetUserByUsername("rene") u2.CreatePost("The Avengers movie was so cool!") u2.CreatePost("Sun shine is beautiful") u1.Follow(u2.Username) } ``` 执行 ``` $ go run cmd/db_init/main.go ``` 然后查看 `follower` 表，里面就有数据了 ![08-01](https://3602083476-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LL8KjUVhGbbzzmqhH-q%2F-LO2UlBfWbAiv6YVxW64%2F-LO2UlexAX9hTbIOxxiX%2F08-01.png?generation=1538730697998808\&alt=media) > 说明: 如上图 user\_id 表示用户， follower\_id 表示关注者， bonfy（id:1) 关注者 只有自己, 而 rene(id:2) 关注者 有两位, 这也是 u1.Follow(u2.Username) 的执行结果 > > 本小节 [Diff](https://github.com/bonfy/go-mega-code/commit/ef4e3aaab2a4ba077edf687e6af7dc2a907df3db) ## 完善页面显示 ### 增加 Follow and Unfollow 操作 controller/home.go ```go ... func (h home) registerRoutes() { r := mux.NewRouter() r.HandleFunc("/logout", middleAuth(logoutHandler)) r.HandleFunc("/login", loginHandler) r.HandleFunc("/register", registerHandler) r.HandleFunc("/user/{username}", middleAuth(profileHandler)) r.HandleFunc("/follow/{username}", middleAuth(followHandler)) r.HandleFunc("/unfollow/{username}", middleAuth(unFollowHandler)) r.HandleFunc("/profile_edit", middleAuth(profileEditHandler)) r.HandleFunc("/", middleAuth(indexHandler)) http.Handle("/", r) } ... func followHandler(w http.ResponseWriter, r *http.Request) { vars := mux.Vars(r) pUser := vars["username"] sUser, _ := getSessionUser(r) err := vm.Follow(sUser, pUser) if err != nil { log.Println("Follow error:", err) w.Write([]byte("Error in Follow")) return } http.Redirect(w, r, fmt.Sprintf("/user/%s", pUser), http.StatusSeeOther) } func unFollowHandler(w http.ResponseWriter, r *http.Request) { vars := mux.Vars(r) pUser := vars["username"] sUser, _ := getSessionUser(r) err := vm.UnFollow(sUser, pUser) if err != nil { log.Println("UnFollow error:", err) w.Write([]byte("Error in UnFollow")) return } http.Redirect(w, r, fmt.Sprintf("/user/%s", pUser), http.StatusSeeOther) } ``` `Follow` 和 `Unfollow`之后通过 Redirect 回到原来的页面 ### 完善Profile页面 vm/profile.go ```go package vm import "github.com/bonfy/go-mega-code/model" // ProfileViewModel struct type ProfileViewModel struct { BaseViewModel Posts []model.Post Editable bool IsFollow bool FollowersCount int FollowingCount int ProfileUser model.User } // ProfileViewModelOp struct type ProfileViewModelOp struct{} // GetVM func func (ProfileViewModelOp) GetVM(sUser, pUser string) (ProfileViewModel, error) { v := ProfileViewModel{} v.SetTitle("Profile") u, err := model.GetUserByUsername(pUser) if err != nil { return v, err } posts, _ := model.GetPostsByUserID(u.ID) v.ProfileUser = *u v.Editable = (sUser == pUser) if !v.Editable { v.IsFollow = u.IsFollowedByUser(sUser) } v.FollowersCount = u.FollowersCount() v.FollowingCount = u.FollowingCount() v.Posts = *posts v.SetCurrentUser(sUser) return v, nil } // Follow func : A follow B func Follow(a, b string) error { u, err := model.GetUserByUsername(a) if err != nil { return err } return u.Follow(b) } // UnFollow func : A unfollow B func UnFollow(a, b string) error { u, err := model.GetUserByUsername(a) if err != nil { return err } return u.Unfollow(b) } ``` templates/content/profile.html ```markup ... {{if .ProfileUser.LastSeen}}

Last seen on: {{ .ProfileUser.LastSeen }}

{{end}}

{{ .FollowersCount }} followers, {{ .FollowingCount }} following.

{{if .Editable}}

Edit your profile

{{else}} {{if .IsFollow}}

Unfollow

{{else}}

Follow

{{end}} {{end}} ... ``` 运行 ``` $ go run main.go ``` ![08-02](https://3602083476-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LL8KjUVhGbbzzmqhH-q%2F-LO2UlBfWbAiv6YVxW64%2F-LO2Ulf2w4gEVJ1R9WSI%2F08-02.png?generation=1538730698136385\&alt=media) > 说明: 这个是通过 rene 登陆之后访问 `http://127.0.0.1:8888/user/bonfy` 查看 bonfy 的profile, 由于 rene 没有 follow bonfy，可以点击 `Follow` 按钮，实现Follow操作 > > 本小节 [Diff](https://github.com/bonfy/go-mega-code/commit/b1502cf92a9e1ee9f77cfa2b661646e6e4fd414c) ## Links * [目录](https://go-mega.bonfy.im/master) * 上一节: [07-Profile-Page-And-Avatar](https://go-mega.bonfy.im/07-profile-page-and-avatar) * 下一节: [09-Pagination](https://go-mega.bonfy.im/09-pagination)