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, Diff, 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

...
// 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

// 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

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

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

完善页面显示

增加 Follow and Unfollow 操作

controller/home.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)
}

FollowUnfollow之后通过 Redirect 回到原来的页面

完善Profile页面

vm/profile.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

...
{{if .ProfileUser.LastSeen}}
<p>Last seen on: {{ .ProfileUser.LastSeen }}</p>
{{end}}
<p>{{ .FollowersCount }} followers, {{ .FollowingCount }} following.</p>
{{if .Editable}}
<p><a href="/profile_edit">Edit your profile</a></p>
{{else}}
{{if .IsFollow}}
<p><a href="/unfollow/{{.ProfileUser.Username}}">Unfollow</a></p>
{{else}}
<p><a href="/follow/{{.ProfileUser.Username}}">Follow</a></p>
{{end}}
{{end}}
...

运行

$ go run main.go
08-02

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

Links