09-Pagination add paginate

controller/g.go

@@ -12,13 +12,15 @@ var (
 	sessionName    string
 	flashName      string
 	store          *sessions.CookieStore
+	pageLimit      int
 )
 
 func init() {
 	templates = PopulateTemplates()
 	store = sessions.NewCookieStore([]byte("something-very-secret"))
 	sessionName = "go-mega"
 	flashName = "go-flash"
+	pageLimit = 5
 }
 
 // Startup func

controller/home.go

@@ -28,10 +28,11 @@ func (h home) registerRoutes() {
 func indexHandler(w http.ResponseWriter, r *http.Request) {
 	tpName := "index.html"
 	vop := vm.IndexViewModelOp{}
+	page := getPage(r)
 	username, _ := getSessionUser(r)
 	if r.Method == http.MethodGet {
 		flash := getFlash(w, r)
-		v := vop.GetVM(username, flash)
+		v := vop.GetVM(username, flash, page, pageLimit)
 		templates[tpName].Execute(w, &v)
 	}
 	if r.Method == http.MethodPost {
@@ -119,8 +120,9 @@ func profileHandler(w http.ResponseWriter, r *http.Request) {
 	vars := mux.Vars(r)
 	pUser := vars["username"]
 	sUser, _ := getSessionUser(r)
+	page := getPage(r)
 	vop := vm.ProfileViewModelOp{}
-	v, err := vop.GetVM(sUser, pUser)
+	v, err := vop.GetVM(sUser, pUser, page, pageLimit)
 	if err != nil {
 		msg := fmt.Sprintf("user ( %s ) does not exist", pUser)
 		w.Write([]byte(msg))

controller/utils.go

@@ -8,6 +8,7 @@ import (
 	"net/http"
 	"os"
 	"regexp"
+	"strconv"
 
 	"github.com/bonfy/go-mega-code/vm"
 )
@@ -192,3 +193,19 @@ func getFlash(w http.ResponseWriter, r *http.Request) string {
 	session.Save(r, w)
 	return fmt.Sprintf("%v", fm[0])
 }
+
+func getPage(r *http.Request) int {
+	url := r.URL         // net/url.URL
+	query := url.Query() // Values (map[string][]string)
+
+	q := query.Get("page")
+	if q == "" {
+		return 1
+	}
+
+	page, err := strconv.Atoi(q)
+	if err != nil {
+		return 1
+	}
+	return page
+}

model/post.go

@@ -21,3 +21,15 @@ func GetPostsByUserID(id int) (*[]Post, error) {
 	}
 	return &posts, nil
 }
+
+// GetPostsByUserIDPageAndLimit func
+func GetPostsByUserIDPageAndLimit(id, page, limit int) (*[]Post, int, error) {
+	var total int
+	var posts []Post
+	offset := (page - 1) * limit
+	if err := db.Preload("User").Order("timestamp desc").Where("user_id=?", id).Offset(offset).Limit(limit).Find(&posts).Error; err != nil {
+		return nil, total, err
+	}
+	db.Model(&Post{}).Where("user_id=?", id).Count(&total)
+	return &posts, total, nil
+}

model/user.go

@@ -96,6 +96,19 @@ func (u *User) FollowingPosts() (*[]Post, error) {
 	return &posts, nil
 }
 
+// FollowingPostsByPageAndLimit func
+func (u *User) FollowingPostsByPageAndLimit(page, limit int) (*[]Post, int, error) {
+	var total int
+	var posts []Post
+	offset := (page - 1) * limit
+	ids := u.FollowingIDs()
+	if err := db.Preload("User").Order("timestamp desc").Where("user_id in (?)", ids).Offset(offset).Limit(limit).Find(&posts).Error; err != nil {
+		return nil, total, err
+	}
+	db.Model(&Post{}).Where("user_id in (?)", ids).Count(&total)
+	return &posts, total, nil
+}
+
 // IsFollowedByUser func
 func (u *User) IsFollowedByUser(username string) bool {
 	user, _ := GetUserByUsername(username)

templates/content/index.html

@@ -16,8 +16,16 @@ <h1>Hello, {{.CurrentUser}}!</h1>
         <table>
             <tr valign="top">
                 <td><img src="{{.User.Avatar}}&s=36"></td>
-                <td>{{ .User.Username }} says:<br>{{ .Body }}</td>
+                <td><a href="/user/{{.User.Username}}">{{ .User.Username }}</a> says:<br>{{ .Body }}</td>
             </tr>
         </table>
     {{end}}
+
+    {{ if gt .PrevPage 0 }}
+        <a href="/?page={{.PrevPage}}">Newer posts</a>
+    {{ end }}
+    {{ if gt .NextPage 0 }}
+        <a href="/?page={{.NextPage}}">Older posts</a>
+    {{ end }}
+
 {{end}}

templates/content/profile.html

@@ -34,9 +34,16 @@ <h1>User: {{.ProfileUser.Username}}</h1>
         <table>
             <tr valign="top">
                 <td><img src="{{.User.Avatar}}&s=36"></td>
-                <td>{{ .User.Username }} says:<br>{{ .Body }}</td>
+                <td><a href="/user/{{.User.Username}}">{{ .User.Username }}</a> says:<br>{{ .Body }}</td>
             </tr>
         </table>
     {{end}}
 
+    {{ if gt .PrevPage 0 }}
+        <a href="/user/{{.ProfileUser.Username}}?page={{.PrevPage}}">Newer posts</a>
+    {{ end }}
+    {{ if gt .NextPage 0 }}
+        <a href="/user/{{.ProfileUser.Username}}?page={{.NextPage}}">Older posts</a>
+    {{ end }}
+
 {{end}}

vm/g.go

@@ -15,3 +15,31 @@ func (v *BaseViewModel) SetTitle(title string) {
 func (v *BaseViewModel) SetCurrentUser(username string) {
 	v.CurrentUser = username
 }
+
+// BasePageViewModel struct
+type BasePageViewModel struct {
+	PrevPage    int
+	NextPage    int
+	Total       int
+	CurrentPage int
+	Limit       int
+}
+
+// SetPrevAndNextPage func
+func (v *BasePageViewModel) SetPrevAndNextPage() {
+	if v.CurrentPage > 1 {
+		v.PrevPage = v.CurrentPage - 1
+	}
+
+	if (v.Total-1)/v.Limit >= v.CurrentPage {
+		v.NextPage = v.CurrentPage + 1
+	}
+}
+
+// SetBasePageViewModel func
+func (v *BasePageViewModel) SetBasePageViewModel(total, page, limit int) {
+	v.Total = total
+	v.CurrentPage = page
+	v.Limit = limit
+	v.SetPrevAndNextPage()
+}

vm/index.go

@@ -7,16 +7,22 @@ type IndexViewModel struct {
 	BaseViewModel
 	Posts []model.Post
 	Flash string
+
+	BasePageViewModel
 }
 
 // IndexViewModelOp struct
 type IndexViewModelOp struct{}
 
 // GetVM func
-func (IndexViewModelOp) GetVM(username string, flash string) IndexViewModel {
+func (IndexViewModelOp) GetVM(username, flash string, page, limit int) IndexViewModel {
 	u, _ := model.GetUserByUsername(username)
-	posts, _ := u.FollowingPosts()
-	v := IndexViewModel{BaseViewModel{Title: "Homepage"}, *posts, flash}
+	posts, total, _ := u.FollowingPostsByPageAndLimit(page, limit)
+	v := IndexViewModel{}
+	v.SetTitle("Homepage")
+	v.Posts = *posts
+	v.Flash = flash
+	v.SetBasePageViewModel(total, page, limit)
 	v.SetCurrentUser(username)
 	return v
 }

vm/profile.go

@@ -11,23 +11,24 @@ type ProfileViewModel struct {
 	FollowersCount int
 	FollowingCount int
 	ProfileUser    model.User
+	BasePageViewModel
 }
 
 // ProfileViewModelOp struct
 type ProfileViewModelOp struct{}
 
 // GetVM func
-func (ProfileViewModelOp) GetVM(sUser, pUser string) (ProfileViewModel, error) {
+func (ProfileViewModelOp) GetVM(sUser, pUser string, page, limit int) (ProfileViewModel, error) {
 	v := ProfileViewModel{}
 	v.SetTitle("Profile")
 	u, err := model.GetUserByUsername(pUser)
 	if err != nil {
 		return v, err
 	}
-	posts, _ := model.GetPostsByUserID(u.ID)
+	posts, total, _ := model.GetPostsByUserIDPageAndLimit(u.ID, page, limit)
 	v.ProfileUser = *u
 	v.Editable = (sUser == pUser)
-
+	v.SetBasePageViewModel(total, page, limit)
 	if !v.Editable {
 		v.IsFollow = u.IsFollowedByUser(sUser)
 	}