Add BE validator

cmd/api/handlers-api.go

@@ -9,6 +9,7 @@ import (
 	"myapp/internal/cards/encryption"
 	"myapp/internal/models"
 	"myapp/internal/urlsigner"
+	"myapp/internal/validator"
 	"net/http"
 	"strconv"
 	"strings"
@@ -124,6 +125,14 @@ func (app *application) CreateCustomerAndSubscribeToPlan(w http.ResponseWriter,
 		return
 	}
 
+	// validate data
+	v := validator.New()
+	v.Check(len(data.FirstName) > 1, "first_name", "must be at least 2 characters")
+	if !v.Valid() {
+		app.failedValidation(w, r, v.Errors)
+		return
+	}
+
 	app.infoLog.Println(data.Email, data.LastFour, data.PaymentMethod, data.Plan)
 
 	card := cards.Card{

cmd/api/helpers.go

@@ -95,3 +95,20 @@ func (app *application) passwordMatches(hash, password string) (bool, error) {
 
 	return true, nil
 }
+
+func (app *application) failedValidation(
+	w http.ResponseWriter,
+	r *http.Request,
+	errors map[string]string,
+) {
+	var payload struct {
+		OK      bool              `json:"ok"`
+		Message string            `json:"message"`
+		Errors  map[string]string `json:"errors"`
+	}
+
+	payload.OK = false
+	payload.Message = "failed validation"
+	payload.Errors = errors
+	app.writeJSON(w, http.StatusUnprocessableEntity, payload)
+}

cmd/web/templates/bronze-plan.page.gohtml

@@ -14,18 +14,22 @@ Bronze Plan
       class="d-blick needs-validation charge-form"
       autocomplete="off"
       novalidate="">
-    <input type="hidden" id="product_id" name="product_id" value="{{$widget.ID}}">
+    <input type="hidden"
+           id="product_id"
+           name="product_id"
+           value="{{$widget.ID}}">
     <input type="hidden" id="amount" name="amount" value="{{$widget.Price}}">
     <p class="mt-2 mb-3 text-center">{{$widget.Description}}</p>
     <hr>
     <div class="mb-3">
-        <label for="first-name" class="form-label">First Name</label>
+        <label for="first_name" class="form-label">First Name</label>
         <input type="text"
-               id="first-name"
+               id="first_name"
                name="first_name"
-               autocomplete="first-name-new"
+               autocomplete="first_name-new"
                required=""
                class="form-control">
+        <div id="first_name-help" class="d-none"></div>
     </div>
     <div class="mb-3">
         <label for="last-name" class="form-label">Last Name</label>

internal/validator/validator.go

@@ -0,0 +1,25 @@
+package validator
+
+type Validator struct {
+	Errors map[string]string
+}
+
+func New() *Validator {
+	return &Validator{Errors: make(map[string]string)}
+}
+
+func (v *Validator) Valid() bool {
+	return len(v.Errors) == 0
+}
+
+func (v *Validator) AddError(key, message string) {
+	if _, exists := v.Errors[key]; !exists {
+		v.Errors[key] = message
+	}
+}
+
+func (v *Validator) Check(ok bool, key, message string) {
+	if !ok {
+		v.AddError(key, message)
+	}
+}

static/js/stripe-plan.js

@@ -47,7 +47,7 @@ function stripePaymentMethodHandler(result, plan_id, api) {
             card_brand: result.paymentMethod.card.brand,
             expiry_month: result.paymentMethod.card.exp_month,
             expiry_year: result.paymentMethod.card.exp_year,
-            first_name: document.getElementById("first-name").value,
+            first_name: document.getElementById("first_name").value,
             last_name: document.getElementById("last-name").value,
             amount: document.getElementById("amount").value,
         };
@@ -65,9 +65,22 @@ function stripePaymentMethodHandler(result, plan_id, api) {
             .then(response => response.json())
             .then(function (data) {
                 console.log(data);
+                if (data.ok === false) {
+                    document.getElementById("charge_form").classList.remove("was-validated")
+                    Object.entries(data.errors).forEach((i) => {
+                        const [key, value] = i
+                        document.getElementById(key).classList.add("is-invalid");
+                        document.getElementById(key + "-help").classList.remove("valid-feedback");
+                        document.getElementById(key + "-help").classList.remove("d-none");
+                        document.getElementById(key + "-help").classList.add("invalid-feedback");
+                        document.getElementById(key + "-help").innerText = value;
+                    });
+                    showPayButton();
+                    return
+                }
                 processing.classList.add("d-none");
                 showSuccess("card-messages", "Transaction successful!");
-                sessionStorage.first_name = document.getElementById("first-name").value;
+                sessionStorage.first_name = document.getElementById("first_name").value;
                 sessionStorage.last_name = document.getElementById("last-name").value;
                 sessionStorage.amount = document.getElementById("amount").value;
                 sessionStorage.last_four = result.paymentMethod.card.last4;