add form validation

templates/post.html

@@ -20,8 +20,10 @@
                     <div class="text-right">
                         <form action="/threads/{{.Thread.ID}}/{{.Post.ID}}" method="POST">
                             {{.CSRF}}
-                            <textarea name="content" class="form-control border-0 border-bottom-1 p-3"
+                            <textarea name="content" class="form-control border-0 border-bottom-1 p-3 {{with .Form.Errors.Content}}is-invalid{{end}}"
-                                placeholder="What are your thoughts?" rows="4"></textarea>
+                                placeholder="What are your thoughts?" rows="4">
+                                {{- with .Form.Content}}{{.}}{{end -}}
+                            </textarea>
                             <div class="border-top p-1">
                                 <button class="btn btn-primary btn-sm">Comment</button>
                             </div>

templates/post_create.html

@@ -9,12 +9,19 @@
                     {{.CSRF}}
                     <div class="form-group">
                         <label>Title</label>
-                        <input name="title" type="text" class="form-control" placeholder="Give your post a great title">
+                        <input name="title" type="text" class="form-control {{with .Form.Errors.Title}}is-invalid{{end}}" placeholder="Give your post a great title" value="{{with .Form.Title}}{{.}}{{end}}">
+                        {{with .Form.Errors.Title}}
+                            <div class="invalid-feedack">{{.}}</div>
+                        {{end}}
                     </div>
                     <div class="form-group">
                         <label>Text</label>
-                        <textarea name="content" class="form-control" rows="3"
+                        <textarea name="content" class="form-control {{with .Form.Errors.Content}}is-invalid{{end}}" rows="3" placeholder="Tell people about your thoughts">
-                            placeholder="Tell people about your thoughts"></textarea>
+                            {{- with .Form.Content}}{{.}}{{end -}}
+                        </textarea>
+                            {{with .Form.Errors.Content}}
+                            <div class="invalid-feedack">{{.}}</div>
+                            {{end}}
                     </div>
                     <button type="submit" class="btn btn-primary">Submit Post</button>
                 </form>

templates/thread_create.html

@@ -7,12 +7,20 @@
                     {{.CSRF}}
                     <div class="form-group">
                         <label>Title</label>
-                        <input name="title" type="text" class="form-control" placeholder="Give your thread a great title">
+                        <input name="title" type="text" class="form-control {{with .Form.Errors.Title}}is-invalid{{end}}" placeholder="Give your thread a great title" value="{{with .Form.Title}}{{.}}{{end}}">
+                        {{with .Form.Errors.Title}}
+                        <div class="invalid-feedack">{{.}}</div>
+                        {{end}}
                     </div>
                     <div class="form-group">
                         <label>Description</label>
-                        <textarea name="description" class="form-control" rows="3"
+                        <textarea name="description" class="form-control {{with .Form.Errors.Description}}is-invalid{{end}}" rows="3"
-                            placeholder="Tell people what your thread is about"></textarea>
+                            placeholder="Tell people what your thread is about">
+                            {{- with .Form.Description}}{{.}}{{end -}}
+                        </textarea>
+                        {{with .Form.Errors.Description}}
+                        <div class="invalid-feedack">{{.}}</div>
+                        {{end}}
                     </div>
                     <button type="submit" class="btn btn-primary">Create Thread</button>
                 </form>

web/comment_handler.go

@@ -16,7 +16,15 @@ type CommentHandler struct {
 
 func (h *CommentHandler) Store() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
-		content := r.FormValue("content")
+		form := CreateCommentForm{
+			Content: r.FormValue("content"),
+		}
+		if !form.Validate() {
+			h.sessions.Put(r.Context(), "form", form)
+			http.Redirect(w, r, r.Referer(), http.StatusFound)
+			return
+		}
+
 		idStr := chi.URLParam(r, "postID")
 
 		id, err := uuid.Parse(idStr)
@@ -28,7 +36,7 @@ func (h *CommentHandler) Store() http.HandlerFunc {
 		if err := h.store.CreateComment(&goddit.Comment{
 			ID:      uuid.New(),
 			PostID:  id,
-			Content: content,
+			Content: form.Content,
 		}); err != nil {
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 			return

web/forms.go

@@ -0,0 +1,68 @@
+package web
+
+import "encoding/gob"
+
+func init() {
+	gob.Register(CreatePostForm{})
+	gob.Register(CreateThreadForm{})
+	gob.Register(CreateCommentForm{})
+	gob.Register(FormErrors{})
+}
+
+type FormErrors map[string]string
+
+type CreatePostForm struct {
+	Title   string
+	Content string
+
+	Errors FormErrors
+}
+
+func (f *CreatePostForm) Validate() bool {
+	f.Errors = FormErrors{}
+
+	if f.Title == "" {
+		f.Errors["Title"] = "Please enter a title!"
+	}
+	if f.Content == "" {
+		f.Errors["Content"] = "Please enter a text!"
+	}
+
+	return len(f.Errors) == 0
+}
+
+type CreateThreadForm struct {
+	Title       string
+	Description string
+
+	Errors FormErrors
+}
+
+func (f *CreateThreadForm) Validate() bool {
+	f.Errors = FormErrors{}
+
+	if f.Title == "" {
+		f.Errors["Title"] = "Please enter a title!"
+	}
+	if f.Description == "" {
+		f.Errors["Description"] = "Please enter a description!"
+	}
+
+	return len(f.Errors) == 0
+}
+
+type CreateCommentForm struct {
+	Content string
+
+	Errors FormErrors
+}
+
+func (f *CreateCommentForm) Validate() bool {
+	f.Errors = FormErrors{}
+
+	if f.Content == "" {
+		f.Errors["Content"] = "Please enter a comment!"
+	}
+
+	return len(f.Errors) == 0
+}

web/post_handler.go

@@ -102,8 +102,15 @@ func (h *PostHandler) Show() http.HandlerFunc {
 
 func (h *PostHandler) Store() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
-		title := r.FormValue("title")
+		form := CreatePostForm{
-		content := r.FormValue("content")
+			Title:   r.FormValue("title"),
+			Content: r.FormValue("content"),
+		}
+		if !form.Validate() {
+			h.sessions.Put(r.Context(), "form", form)
+			http.Redirect(w, r, r.Referer(), http.StatusFound)
+			return
+		}
 
 		idStr := chi.URLParam(r, "id")
 
@@ -122,8 +129,8 @@ func (h *PostHandler) Store() http.HandlerFunc {
 		p := &goddit.Post{
 			ID:       uuid.New(),
 			ThreadID: t.ID,
-			Title:    title,
+			Title:    form.Title,
-			Content:  content,
+			Content:  form.Content,
 		}
 
 		if err := h.store.CreatePost(p); err != nil {

web/sessions.go

@@ -22,6 +22,7 @@ func NewSessionsManager(dataSourceName string) (*scs.SessionManager, error) {
 
 type SessionData struct {
 	FlashMessage string
+	Form         interface{}
 	// UserID           uuid.UUID
 }
 
@@ -31,5 +32,10 @@ func GetSessionData(session *scs.SessionManager, ctx context.Context) SessionDat
 	data.FlashMessage = session.PopString(ctx, "flash")
 	// data.UserID, _ = session.Get(ctx "user_id").(uuid.UUID)
 
+	data.Form = session.Pop(ctx, "form")
+	if data.Form == nil {
+		data.Form = map[string]string{}
+	}
+
 	return data
 }

web/thread_handler.go

@@ -91,13 +91,20 @@ func (h *ThreadHandler) Show() http.HandlerFunc {
 
 func (h *ThreadHandler) Store() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
-		title := r.FormValue("title")
+		form := CreateThreadForm{
-		description := r.FormValue("description")
+			Title:       r.FormValue("title"),
+			Description: r.FormValue("description"),
+		}
+		if !form.Validate() {
+			h.sessions.Put(r.Context(), "form", form)
+			http.Redirect(w, r, r.Referer(), http.StatusFound)
+			return
+		}
 
 		if err := h.store.CreateThread(&goddit.Thread{
 			ID:          uuid.New(),
-			Title:       title,
+			Title:       form.Title,
-			Description: description,
+			Description: form.Description,
 		}); err != nil {
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 			return