From 4e40ef8ed90ce217e4209256136929acc35935c7 Mon Sep 17 00:00:00 2001
From: tamsin johnson <tomjohnson@ucsb.edu>
Date: Tue, 6 Feb 2024 16:46:46 -0800
Subject: [PATCH] lets-go:8.6 form parsing

---
 snippetbox/cmd/web/handlers.go | 24 +++++++-----------------
 snippetbox/cmd/web/helpers.go  | 24 ++++++++++++++++++++++++
 snippetbox/cmd/web/main.go     |  5 +++++
 snippetbox/go.mod              |  1 +
 snippetbox/go.sum              |  3 +++
 5 files changed, 40 insertions(+), 17 deletions(-)

diff --git a/snippetbox/cmd/web/handlers.go b/snippetbox/cmd/web/handlers.go
index 6e5176d..64fa536 100644
--- a/snippetbox/cmd/web/handlers.go
+++ b/snippetbox/cmd/web/handlers.go
@@ -63,32 +63,22 @@ func (app *application) snippetCreate(w http.ResponseWriter, r *http.Request) {
 }
 
 type snippetCreateForm struct {
-	Title       string
-	Content     string
-	Expires     int
-	validator.Validator
+	Title       string  `form:"title"`
+	Content     string  `form:"content"`
+	Expires     int     `form:"expires"`
+	validator.Validator `form:"-"`
 }
 
 // snippetCreatePost ...
 func (app *application) snippetCreatePost(w http.ResponseWriter, r *http.Request) {
-	err := r.ParseForm()
+	var form snippetCreateForm
+
+	err := app.decodePostForm(r, &form)
 	if err != nil {
 		app.clientError(w, http.StatusBadRequest)
 		return
 	}
 
-	expires, err := strconv.Atoi(r.PostForm.Get("expires"))
-	if err != nil {
-		app.clientError(w, http.StatusBadRequest)
-		return
-	}
-
-	form := snippetCreateForm{
-		Title:       r.PostForm.Get("title"),
-		Content:     r.PostForm.Get("content"),
-		Expires:     expires,
-	}
-
 	form.CheckField(validator.NotBlank(form.Title), "title", "This field cannot be blank")
 	form.CheckField(validator.MaxChars(form.Title, 100), "title", "This field cannot be more than 100 characters long")
 	form.CheckField(validator.NotBlank(form.Content), "content", "This field cannot be blank")
diff --git a/snippetbox/cmd/web/helpers.go b/snippetbox/cmd/web/helpers.go
index 13a9866..6fb5e0c 100644
--- a/snippetbox/cmd/web/helpers.go
+++ b/snippetbox/cmd/web/helpers.go
@@ -2,11 +2,14 @@ package main
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"log/slog"
 	"net/http"
 	"runtime/debug"
 	"time"
+
+	"github.com/go-playground/form/v4"
 )
 
 // newTemplateData ...
@@ -56,3 +59,24 @@ func (app *application) clientError(w http.ResponseWriter, status int) {
 func (app *application) notFound(w http.ResponseWriter) {
 	app.clientError(w, http.StatusNotFound)
 }
+
+// (app *application)  ...
+func (app *application) decodePostForm(r *http.Request, dst any) error {
+	err := r.ParseForm()
+	if err != nil {
+		return err
+	}
+
+	err = app.formDecoder.Decode(dst, r.PostForm)
+	if err != nil {
+		var invalidDecoderError *form.InvalidDecoderError
+
+		if errors.As(err, &invalidDecoderError) {
+			panic(err)
+		}
+
+		return err
+	}
+
+	return nil
+}
diff --git a/snippetbox/cmd/web/main.go b/snippetbox/cmd/web/main.go
index 1a09036..bc5f130 100644
--- a/snippetbox/cmd/web/main.go
+++ b/snippetbox/cmd/web/main.go
@@ -11,6 +11,7 @@ import (
 
 	"snippetbox.chaosfem.tw/internal/models"
 
+	"github.com/go-playground/form/v4"
 	_ "github.com/go-sql-driver/mysql"
 )
 
@@ -19,6 +20,7 @@ type application struct {
 	logger *slog.Logger
 	snippets *models.SnippetModel
 	templateCache map[string]*template.Template
+	formDecoder *form.Decoder
 }
 
 // main it's the snippetbox webapp
@@ -46,11 +48,14 @@ func main() {
 		os.Exit(1)
 	}
 
+	formDecoder := form.NewDecoder()
+
 	// setup the application
 	app := &application{
 		logger: logger,
 		snippets: &models.SnippetModel{DB: db},
 		templateCache: templateCache,
+		formDecoder: formDecoder,
 	}
 
 	logger.Info("starting server", slog.String("addr", *addr))
diff --git a/snippetbox/go.mod b/snippetbox/go.mod
index d6e5a42..84b9d0d 100644
--- a/snippetbox/go.mod
+++ b/snippetbox/go.mod
@@ -3,6 +3,7 @@ module snippetbox.chaosfem.tw
 go 1.21.4
 
 require (
+	github.com/go-playground/form/v4 v4.2.1 // indirect
 	github.com/go-sql-driver/mysql v1.7.1 // indirect
 	github.com/julienschmidt/httprouter v1.3.0 // indirect
 	github.com/justinas/alice v1.2.0 // indirect
diff --git a/snippetbox/go.sum b/snippetbox/go.sum
index 5138436..a9f8f45 100644
--- a/snippetbox/go.sum
+++ b/snippetbox/go.sum
@@ -1,3 +1,6 @@
+github.com/go-playground/assert/v2 v2.0.1/go.mod h1:VDjEfimB/XKnb+ZQfWdccd7VUvScMdVu0Titje2rxJ4=
+github.com/go-playground/form/v4 v4.2.1 h1:HjdRDKO0fftVMU5epjPW2SOREcZ6/wLUzEobqUGJuPw=
+github.com/go-playground/form/v4 v4.2.1/go.mod h1:q1a2BY+AQUUzhl6xA/6hBetay6dEIhMHjgvJiGo6K7U=
 github.com/go-sql-driver/mysql v1.7.1 h1:lUIinVbN1DY0xBg0eMOzmmtGoHwWBbvnWubQUrtU8EI=
 github.com/go-sql-driver/mysql v1.7.1/go.mod h1:OXbVy3sEdcQ2Doequ6Z5BW6fXNQTmx+9S1MCJN5yJMI=
 github.com/julienschmidt/httprouter v1.3.0 h1:U0609e9tgbseu3rBINet9P48AI/D3oJs4dN7jwJOQ1U=