Use slugs too to select invoice products without JavaScript

The product search returns a list of products using its slug as the
“external key”, because i do not want people seeing the id in links,
and the search product list is just a different rendering of the product
index table.

However, now i had two almost identical select queries for product,
one using the product_id and the other its slug, the former intended for
the form to select products using checkboxes—the one non-JavaScript
users see—and the latter for the product search.

Using the slug in both forms i can now simplify the code and have a
single query.

pkg/invoices.go

@@ -437,13 +437,13 @@ func mustRenderNewInvoiceProductsForm(w http.ResponseWriter, r *http.Request, ac
 }
 
 func mustGetProductChoices(ctx context.Context, conn *Conn, company *Company) []*productChoice {
-	rows := conn.MustQuery(ctx, "select product.product_id, product.name, to_price(price, decimal_digits) from product join company using (company_id) join currency using (currency_code) where company_id = $1 order by name", company.Id)
+	rows := conn.MustQuery(ctx, "select product.slug, product.name, to_price(price, decimal_digits) from product join company using (company_id) join currency using (currency_code) where company_id = $1 order by name", company.Id)
 	defer rows.Close()
 
 	var choices []*productChoice
 	for rows.Next() {
 		entry := &productChoice{}
-		if err := rows.Scan(&entry.Id, &entry.Name, &entry.Price); err != nil {
+		if err := rows.Scan(&entry.Slug, &entry.Name, &entry.Price); err != nil {
 			panic(err)
 		}
 		choices = append(choices, entry)
@@ -462,7 +462,7 @@ type newInvoiceProductsPage struct {
 }
 
 type productChoice struct {
-	Id    int
+	Slug  string
 	Name  string
 	Price string
 }
@@ -664,8 +664,29 @@ func (form *invoiceForm) Update() {
 	}
 }
 
-func (form *invoiceForm) AddProducts(ctx context.Context, conn *Conn, productsId []string) {
+const selectProductBySlug = `
-	form.mustAddProductsFromQuery(ctx, conn, "select '', product_id, name, description, to_price(price, decimal_digits), 1 as quantity, 0 as discount, array_remove(array_agg(tax_id), null) from product join company using (company_id) join currency using (currency_code) left join product_tax using (product_id) where product_id = any ($1) group by product_id, name, description, price, decimal_digits", productsId)
+		select ''
+		     , product_id
+		     , name
+		     , description
+		     , to_price(price, decimal_digits)
+		     , 1 as quantity
+		     , 0 as discount
+		     , array_remove(array_agg(tax_id), null)
+		from product
+	    join company using (company_id)
+		join currency using (currency_code)
+		left join product_tax using (product_id)
+		where product.slug = any ($1)
+		group by product_id
+		       , name
+		       , description
+		       , price
+		       , decimal_digits
+	`
+
+func (form *invoiceForm) AddProducts(ctx context.Context, conn *Conn, productsSlug []string) {
+	form.mustAddProductsFromQuery(ctx, conn, selectProductBySlug, productsSlug)
 }
 
 func (form *invoiceForm) mustAddProductsFromQuery(ctx context.Context, conn *Conn, sql string, args ...interface{}) {
@@ -864,25 +885,8 @@ func (form *invoiceProductForm) Update() {
 }
 
 func (form *invoiceProductForm) MustFillFromDatabase(ctx context.Context, conn *Conn, slug string) bool {
-	return !notFoundErrorOrPanic(conn.QueryRow(ctx, `
+	return !notFoundErrorOrPanic(conn.QueryRow(ctx, selectProductBySlug, []string{slug}).Scan(
-		select product_id
+		form.InvoiceProductId,
-		     , name
-		     , description
-		     , to_price(price, decimal_digits)
-		     , 1 as quantity
-		     , 0 as discount
-		     , array_remove(array_agg(tax_id), null)
-		from product
-		join company using (company_id)
-		join currency using (currency_code)
-		left join product_tax using (product_id)
-		where product.slug = $1
-		group by product_id
-		       , name
-		       , description
-		       , price
-		       , decimal_digits
-		       `, slug).Scan(
 		form.ProductId,
 		form.Name,
 		form.Description,
@@ -1006,7 +1010,7 @@ func handleInvoiceAction(w http.ResponseWriter, r *http.Request, action string,
 		w.WriteHeader(http.StatusOK)
 		mustRenderNewInvoiceProductsForm(w, r, action, form)
 	case "add-products":
-		form.AddProducts(r.Context(), conn, r.Form["id"])
+		form.AddProducts(r.Context(), conn, r.Form["slug"])
 		w.WriteHeader(http.StatusOK)
 		renderForm(w, r, form)
 	default:

web/template/invoices/products.gohtml

@@ -52,10 +52,10 @@
                 </thead>
                 <tbody>
                 {{ with .Products }}
-                    {{- range $product, $key := . }}
+                    {{- range . }}
                         <tr>
-                            <td><input type="checkbox" name="id" id="new-product-id-{{$key}}" value="{{.Id}}"></td>
+                            <td><input type="checkbox" name="slug" id="product-{{ .Slug }}" value="{{.Slug}}"></td>
-                            <td><label for="new-product-id-{{$key}}">{{ .Name }}</label></td>
+                            <td><label for="product-{{ .Slug }}">{{ .Name }}</label></td>
                             <td class="numeric">{{ .Price | formatPrice }}</td>
                         </tr>
                     {{- end }}