counter: make click page dynamic to avoid repetitive loading

This makes the whole click page load only once for a normal click
workflow. The current basket is now rendered client side with Vue.JS,
and the backend view is able to answer with JSON if asked to.

This should lighten the workflow a lot on the client side, especially
with poor connectivity, and the server should also feel lighter during
big events, due to far less complex Jinja pages to render.

core/static/core/style.scss

@@ -1125,7 +1125,7 @@ u, .underline {
   overflow: auto;
 }
 
-#bar_ui {
+#click_form {
   float: left;
   min-width: 57%;
 }

counter/templates/counter/counter_click.jinja

@@ -1,23 +1,6 @@
 {% extends "core/base.jinja" %}
 {% from "core/macros.jinja" import user_mini_profile, user_subscription %}
 
-
-{% macro add_product(id, content, class="") %}
-<form method="post" action="{{ url('counter:click', counter_id=counter.id, user_id=customer.user.id) }}" class="{{ class }}">
-    {% csrf_token %}
-    <input type="hidden" name="action" value="add_product">
-    <button type="submit" name="product_id" value="{{ id }}"> {{ content|safe }} </button>
-</form>
-{% endmacro %}
-
-{% macro del_product(id, content, class="") %}
-<form method="post" action="{{ url('counter:click', counter_id=counter.id, user_id=customer.user.id) }}" class="{{ class }}">
-    {% csrf_token %}
-    <input type="hidden" name="action" value="del_product">
-    <button type="submit" name="product_id" value="{{ id }}"> {{ content }} </button>
-</form>
-{% endmacro %}
-
 {% block title %}
 {{ counter }}
 {% endblock %}
@@ -58,56 +41,57 @@
     {% endif %}
 </div>
 <div id="bar_ui">
+    <noscript>
+        <p class="important">Javascript is required for the counter UI.</p>
+    </noscript>
+    <div id="click_form">
         <h5>{% trans %}Selling{% endtrans %}</h5>
         <div>
+
             <div class="important">
-            {% if request.session['too_young'] %}
+                <p v-for="error in errors"><strong>{{ error }}</strong></p>
-            <p><strong>{% trans %}Too young for that product{% endtrans %}</strong></p>
-            {% endif %}
-            {% if request.session['not_allowed'] %}
-            <p><strong>{% trans %}Not allowed for that product{% endtrans %}</strong></p>
-            {% endif %}
-            {% if request.session['no_age'] %}
-            <p><strong>{% trans %}No date of birth provided{% endtrans %}</strong></p>
-            {% endif %}
-            {% if request.session['not_enough'] %}
-            <p><strong>{% trans %}Not enough money{% endtrans %}</strong></p>
-            {% endif %}
             </div>
-        <form method="post" action="{{ url('counter:click', counter_id=counter.id, user_id=customer.user.id) }}">
+
+            <form method="post" action="{{ url('counter:click', counter_id=counter.id, user_id=customer.user.id) }}" class="code_form" @submit.prevent="handle_code">
                 {% csrf_token %}
                 <input type="hidden" name="action" value="code">
                 <input type="input" name="code" value="" class="focus" id="code_field"/>
                 <input type="submit" value="{% trans %}Go{% endtrans %}" />
             </form>
             <p>{% trans %}Basket: {% endtrans %}</p>
+
+            {% raw %}
             <ul>
-            {% for id,infos in request.session['basket']|dictsort %}
+                <li v-for="p_info,p_id in basket">
-            {% set product = counter.products.filter(id=id).first() %}
+
-            {% set s = infos['qty'] * infos['price'] / 100 %}
+                    <form method="post" action="" class="inline del_product_form" @submit.prevent="handle_action">
-            <li>{{ del_product(id, '-', "inline") }} {{ infos['qty'] + infos['bonus_qty'] }} {{ add_product(id, '+', "inline") }}
+                        <input type="hidden" name="csrfmiddlewaretoken" v-bind:value="js_csrf_token">
-            {{ product.name }}: {{ "%0.2f"|format(s) }} €
+                        <input type="hidden" name="action" value="del_product">
-            {% if infos['bonus_qty'] %}
+                        <input type="hidden" name="product_id" v-bind:value="p_id">
-                P
+                        <button type="submit"> - </button>
-            {% endif %}
+                    </form>
+
+                    {{ p_info["qty"] + p_info["bonus_qty"] }}
+
+                    <form method="post" action="" class="inline add_product_form" @submit.prevent="handle_action">
+                        <input type="hidden" name="csrfmiddlewaretoken" v-bind:value="js_csrf_token">
+                        <input type="hidden" name="action" value="add_product">
+                        <input type="hidden" name="product_id" v-bind:value="p_id">
+                        <button type="submit"> + </button>
+                    </form>
+
+                    {{ products[p_id].name }}: {{ (p_info["qty"]*p_info["price"]/100).toLocaleString(undefined, { minimumFractionDigits: 2 }) }} € <span v-if="p_info['bonus_qty'] > 0">P</span>
                 </li>
-            {% endfor %}
             </ul>
-        <p><strong>{% trans %}Total: {% endtrans %}{{ "%0.2f"|format(basket_total) }} €</strong></p>
+            <p>
+                <strong>Total: {{ sum_basket().toLocaleString(undefined, { minimumFractionDigits: 2 }) }} €</strong>
+            </p>
+            {% endraw %}
+
             <div class="important">
-            {% if request.session['too_young'] %}
+                <p v-for="error in errors"><strong>{{ error }}</strong></p>
-            <p><strong>{% trans %}Too young for that product{% endtrans %}</strong></p>
-            {% endif %}
-            {% if request.session['not_allowed'] %}
-            <p><strong>{% trans %}Not allowed for that product{% endtrans %}</strong></p>
-            {% endif %}
-            {% if request.session['no_age'] %}
-            <p><strong>{% trans %}No date of birth provided{% endtrans %}</strong></p>
-            {% endif %}
-            {% if request.session['not_enough'] %}
-            <p><strong>{% trans %}Not enough money{% endtrans %}</strong></p>
-            {% endif %}
             </div>
+
             <form method="post" action="{{ url('counter:click', counter_id=counter.id, user_id=customer.user.id) }}">
                 {% csrf_token %}
                 <input type="hidden" name="action" value="finish">
@@ -130,8 +114,8 @@
             </form>
         </div>
         {% endif %}
-</div>
+    </div>
-<div id="products">
+    <div id="products">
         <ul>
             {% for category in categories.keys() -%}
             <li><a href="#cat_{{ category|slugify }}">{{ category }}</a></li>
@@ -147,19 +131,87 @@
                 {% else %}
                     {% set file = static('core/img/na.gif') %}
                 {% endif %}
-            {% set prod = '<strong>%s</strong><hr><img src="%s" /><span>%s €<br>%s</span>' % (p.name, file, p.selling_price, p.code) %}
+                <form method="post" action="{{ url('counter:click', counter_id=counter.id, user_id=customer.user.id) }}" class="form_button add_product_form" @submit.prevent="handle_action">
-                {{ add_product(p.id, prod, "form_button") }}
+                    {% csrf_token %}
+                    <input type="hidden" name="action" value="add_product">
+                    <input type="hidden" name="product_id" value="{{ p.id }}">
+                    <button type="submit"><strong>{{ p.name }}</strong><hr><img src="{{ file }}" /><span>{{ p.selling_price }} €<br>{{ p.code }}</span></button>
+                </form>
             {%- endfor %}
         </div>
         {%- endfor %}
+    </div>
 </div>
 
 {% endblock %}
 
 {% block script %}
 {{ super() }}
+<script src="{{ static('core/js/vue.global.prod.js') }}"></script>
 <script>
 $( function() {
+    /* Vue.JS dynamic form */
+    const click_form_vue = Vue.createApp({
+        data() {
+            return {
+                js_csrf_token: "{{ csrf_token }}",
+                products: {
+                    {% for p in products -%}
+                      {{ p.id }}: {
+                          code: "{{ p.code }}",
+                          name: "{{ p.name }}",
+                          selling_price: "{{ p.selling_price }}",
+                          special_selling_price: "{{ p.special_selling_price }}",
+                        },
+                    {%- endfor %}
+                  },
+                basket: {{ request.session["basket"]|tojson }},
+                errors: [],
+              }
+        },
+        methods: {
+            sum_basket() {
+                var vm = this;
+                var total = 0;
+                for(idx in vm.basket) {
+                    var item = vm.basket[idx];
+                    console.log(item);
+                    total += item["qty"] * item["price"];
+                }
+                return total / 100;
+            },
+            handle_code(event) {
+                var vm = this;
+                var code = $(event.target).find("#code_field").val().toUpperCase();
+                console.log("Code:");
+                console.log(code);
+                if(code == "{% trans %}END{% endtrans %}" || code == "{% trans %}CAN{% endtrans %}") {
+                    $(event.target).submit();
+                } else {
+                    vm.handle_action(event);
+                }
+            },
+            handle_action(event) {
+                var vm = this;
+                var payload = $(event.target).serialize();
+                $.ajax({
+                    type: 'post',
+                    dataType: 'json',
+                    data: payload,
+                    success: function(response) {
+                        vm.basket = response.basket;
+                        vm.errors = [];
+                    },
+                    error: function(error) {
+                        vm.basket = error.responseJSON.basket;
+                        vm.errors = error.responseJSON.errors;
+                    }
+                });
+                $('form.code_form #code_field').val("").focus();
+              }
+          }
+      }).mount('#bar_ui');
+
     /* Autocompletion in the code field */
     var products_autocomplete = [
     {% for p in products -%}
@@ -196,7 +248,7 @@ $( function() {
     });
 
     /* Accordion UI between basket and refills */
-    $("#bar_ui").accordion({
+    $("#click_form").accordion({
         heightStyle: "content",
         activate: function(event, ui){
             $(".focus").focus();

counter/tests.py

@@ -68,18 +68,31 @@ class CounterTest(TestCase):
             location,
             {
                 "action": "refill",
-                "amount": "10",
+                "amount": "5",
                 "payment_method": "CASH",
                 "bank": "OTHER",
             },
         )
         response = self.client.post(location, {"action": "code", "code": "BARB"})
+        response = self.client.post(location, {"action": "add_product", "product_id": "4"})
+        response = self.client.post(location, {"action": "del_product", "product_id": "4"})
+        response = self.client.post(location, {"action": "code", "code": "2xdeco"})
+        response = self.client.post(location, {"action": "code", "code": "1xbarb"})
         response = self.client.post(location, {"action": "code", "code": "fin"})
 
         response_get = self.client.get(response.get("location"))
+        response_content = response_get.content.decode("utf-8")
         self.assertTrue(
-            "<p>Client : Richard Batsbak - Nouveau montant : 8.30"
+            "<li>2 x Barbar"
-            in str(response_get.content)
+            in str(response_content)
+        )
+        self.assertTrue(
+            "<li>2 x Déconsigne Eco-cup"
+            in str(response_content)
+        )
+        self.assertTrue(
+            "<p>Client : Richard Batsbak - Nouveau montant : 3.60"
+            in str(response_content)
         )
 
 

counter/views.py

@@ -38,7 +38,7 @@ from django.views.generic.edit import (
 from django.forms.models import modelform_factory
 from django.forms import CheckboxSelectMultiple
 from django.urls import reverse_lazy, reverse
-from django.http import HttpResponseRedirect, HttpResponse
+from django.http import HttpResponseRedirect, HttpResponse, JsonResponse
 from django.utils import timezone
 from django import forms
 from django.utils.translation import ugettext_lazy as _
@@ -48,6 +48,7 @@ from django.db import DataError, transaction, models
 import re
 import pytz
 from datetime import date, timedelta, datetime
+from http import HTTPStatus
 from ajax_select.fields import AutoCompleteSelectField, AutoCompleteSelectMultipleField
 from ajax_select import make_ajax_field
 
@@ -357,6 +358,34 @@ class CounterClick(CounterTabsMixin, CanViewMixin, DetailView):
     pk_url_kwarg = "counter_id"
     current_tab = "counter"
 
+    def render_to_response(self, *args, **kwargs):
+        if self.request.is_ajax():  # JSON response for AJAX requests
+            response = {"errors": []}
+            status = HTTPStatus.OK
+
+            if self.request.session["too_young"]:
+                response["errors"].append(_("Too young for that product"))
+                status = HTTPStatus.UNAVAILABLE_FOR_LEGAL_REASONS
+            if self.request.session["not_allowed"]:
+                response["errors"].append(_("Not allowed for that product"))
+                status = HTTPStatus.FORBIDDEN
+            if self.request.session["no_age"]:
+                response["errors"].append(_("No date of birth provided"))
+                status = HTTPStatus.UNAVAILABLE_FOR_LEGAL_REASONS
+            if self.request.session["not_enough"]:
+                response["errors"].append(_("Not enough money"))
+                status = HTTPStatus.PAYMENT_REQUIRED
+
+            if len(response["errors"]) > 1:
+                status = HTTPStatus.BAD_REQUEST
+
+            response["basket"] = self.request.session["basket"]
+
+            return JsonResponse(response, status=status)
+
+        else:  # Standard HTML page
+            return super().render_to_response(*args, **kwargs)
+
     def dispatch(self, request, *args, **kwargs):
         self.customer = get_object_or_404(Customer, user__id=self.kwargs["user_id"])
         obj = self.get_object()