Implement floating price items

src/conftest.py

@@ -15,7 +15,6 @@ def live_server(settings, live_server):
 
 @pytest.fixture()
 def firefox_options(firefox_options):
-    firefox_options.add_argument("-headless")
     return firefox_options
 
 

src/purchase/forms.py

@@ -7,7 +7,8 @@ from django.utils.translation import gettext as _
 from purchase.layout import BasketItemField
 from purchase.models import Basket, Product
 
-PREFIX = "product-"
+PRICED_PREFIX = "product-"
+UNPRICED_PREFIX = "unpriced_product-"
 
 
 class BasketForm(forms.ModelForm):
@@ -31,8 +32,8 @@ class BasketForm(forms.ModelForm):
             for item in basket.items.all():
                 products[item.product] = item.quantity
         fields = []
-        for product in Product.objects.all():
+        for product in Product.objects.with_fixed_price():
-            field_name = f"{PREFIX}{product.id}"
+            field_name = f"{PRICED_PREFIX}{product.id}"
             self.fields.update(
                 {
                     field_name: forms.IntegerField(
@@ -47,6 +48,7 @@ class BasketForm(forms.ModelForm):
             Div(
                 *fields,
                 css_class="row row-cols-2 row-cols-sm-3 row-cols-md-4 row-cols-lg-5 row-cols-xl-6 g-4",
+                css_id="products",
             ),
             InlineRadios("payment_method"),
         )
@@ -56,8 +58,8 @@ class BasketForm(forms.ModelForm):
         name: str
         products = {product.id: product for product in Product.objects.all()}
         for name, value in self.cleaned_data.items():
-            if name.startswith(PREFIX):
+            if name.startswith(PRICED_PREFIX):
-                product_id = int(name.removeprefix(PREFIX))
+                product_id = int(name.removeprefix(PRICED_PREFIX))
                 product = products[product_id]
                 if value > 0:
                     instance.items.update_or_create(

src/purchase/migrations/0013_remove_basketitem_unique_product_per_basket_and_more.py

@@ -0,0 +1,24 @@
+# Generated by Django 4.1.7 on 2023-03-27 13:56
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("purchase", "0012_rename_value_cache_etag_cache_last_modified"),
+    ]
+
+    operations = [
+        migrations.RemoveConstraint(
+            model_name="basketitem",
+            name="unique_product_per_basket",
+        ),
+        migrations.AlterField(
+            model_name="product",
+            name="unit_price_cents",
+            field=models.PositiveIntegerField(
+                help_text="Unit price in cents. Use zero to denote that the product has no fixed price.",
+                verbose_name="unit price (cents)",
+            ),
+        ),
+    ]

src/purchase/models.py

@@ -4,7 +4,7 @@ import hashlib
 import uuid
 
 from django.db import models
-from django.db.models import Avg, Count, F, Sum, UniqueConstraint
+from django.db.models import Avg, Count, F, Sum
 from django.db.models.functions import Coalesce
 from django.urls import reverse
 from django.utils.translation import gettext
@@ -77,6 +77,12 @@ class ProductQuerySet(models.QuerySet):
     def with_sold(self):
         return self.annotate(sold=Coalesce(Sum("basket_items__quantity"), 0))
 
+    def with_fixed_price(self):
+        return self.exclude(unit_price_cents=0)
+
+    def with_no_fixed_price(self):
+        return self.filter(unit_price_cents=0)
+
 
 class ProductManager(models.Manager):
     def get_by_natural_key(self, name):
@@ -88,7 +94,9 @@ class Product(Model):
     image = models.ImageField(null=True, blank=True, verbose_name=_("image"))
     unit_price_cents = models.PositiveIntegerField(
         verbose_name=_("unit price (cents)"),
-        help_text=_("unit price in cents"),
+        help_text=_(
+            "Unit price in cents. Use zero to denote that the product has no fixed price.",
+        ),
     )
     display_order = models.PositiveIntegerField(
         default=default_product_display_order,
@@ -115,6 +123,10 @@ class Product(Model):
             base=16,
         )
 
+    @property
+    def has_fixed_price(self) -> bool:
+        return self.unit_price_cents > 0
+
     def save(self, *args, **kwargs):
         super().save(*args, **kwargs)
         if not self.image:
@@ -223,9 +235,6 @@ class BasketItem(Model):
     class Meta:
         verbose_name = _("basket item")
         verbose_name_plural = _("basket items")
-        constraints = [
-            UniqueConstraint("product", "basket", name="unique_product_per_basket"),
-        ]
 
 
 class Cache(SingletonModel):

src/purchase/templates/purchase/basket_form.html

@@ -1,7 +1,6 @@
 {% extends "common/base.html" %}
-{% load static %}
+{% load i18n static crispy_forms_tags purchase django_htmx %}
-{% load i18n %}
+
-{% load crispy_forms_tags purchase %}
 {% block extrahead %}
     <link rel="stylesheet" href="{% static "purchase/css/basket_form.css" %}">
 {% endblock %}
@@ -18,7 +17,43 @@
         <h1>{% translate "New basket" %}</h1>
     {% endif %}
     {% crispy form %}
+    <form
+        hx-get="{% url "purchase:additional_unpriced_product" %}"
+        hx-target="#products"
+        hx-swap="beforeend"
+    >
+        <div class="input-group">
+            <select class="form-select" name="product_to_add" id="product_to_add">
+                {% for product in products %}
+                    <option value="{{ product.pk }}">{{ product.name }}</option>
+                {% endfor %}
+            </select>
+            <button
+                class="btn btn-outline-secondary"
+                type="submit"
+                id="add_product"
+            >
+                {% translate "Add product" %}
+            </button>
+        </div>
+    </form>
+    {% for item in basket.items.all %}
+        {% if item.product.unit_price_cents == 0 %}
+            <input
+                type="hidden"
+                hx-get="{% url "purchase:additional_unpriced_product" %}?product_to_add={{ item.product.pk }}&value={{ item.unit_price_cents }}"
+                hx-trigger="load"
+                hx-target="#products"
+                hx-swap="beforeend"
+            >
+        {% endif %}
+    {% endfor %}
     {% if basket %}
         <a href="{% url "purchase:new" %}" class="btn btn-secondary">{% translate "New" %}</a>
     {% endif %}
 {% endblock %}
+
+{% block extrascript %}
+    <script src="{% static 'vendor/htmx-1.8.6/htmx.min.js' %}" defer></script>
+    {% django_htmx_script %}
+{% endblock %}

src/purchase/templates/purchase/snippets/basket_unpriced_item.html

@@ -0,0 +1,23 @@
+{% load crispy_forms_field %}
+<div class="col">
+    <div class="card h-100 bg-success text-white" data-product-id="{{ product.pk }}">
+        {% if product.image %}
+            <img src="{{ product.image.url }}" class="card-img">
+        {% else %}
+            <div class="card-img product-img-placeholder"
+                 style="background-color: hsl({{ product.color_hue }}, 60%, 80%)">
+                <span>
+                    {{ product.name|slice:"1" }}
+                </span>
+            </div>
+        {% endif %}
+        <div class="card-body">
+            <h4 class="card-title">{{ product.name }}</h4>
+            <div class="input-group">
+                <input type="number" step="0.01" name="unpriced_product-{{ product.pk }}" min="0" class="numberinput form-control" required="" id="unpriced_id_product-{{ product.pk }}"
+                       value="{{ value|default:0 }}"
+                >
+            </div>
+        </div>
+    </div>
+</div>

src/purchase/tests/test_cashier_flow.py

@@ -6,6 +6,7 @@ from pytest_django.live_server_helper import LiveServer
 from selenium.webdriver import ActionChains, Keys
 from selenium.webdriver.common.by import By
 from selenium.webdriver.remote.webdriver import WebDriver
+from selenium.webdriver.support.select import Select
 from selenium.webdriver.support.wait import WebDriverWait
 
 from common.models import User
@@ -34,6 +35,11 @@ def test_cashier_create_and_update_basket(  # noqa: PLR0915
         ProductFactory(),
         ProductFactory(),
     ]
+    unpriced_products = [
+        ProductFactory(unit_price_cents=0),
+        ProductFactory(unit_price_cents=0),
+        ProductFactory(unit_price_cents=0),
+    ]
     payment_methods = [
         PaymentMethodFactory(),
         PaymentMethodFactory(),
@@ -85,6 +91,29 @@ def test_cashier_create_and_update_basket(  # noqa: PLR0915
     chain.double_click(quantity_input).perform()
     quantity_input.send_keys("4")
 
+    # Add non-fixed priced product
+    select = Select(selenium.find_element(By.ID, "product_to_add"))
+    unpriced_product = unpriced_products[1]
+    select.select_by_value(str(unpriced_product.pk))
+    selenium.find_element(By.ID, "add_product").click()
+    selenium.find_element(By.ID, "add_product").click()
+    elements = selenium.find_elements(
+        By.CSS_SELECTOR,
+        f"[data-product-id='{unpriced_product.pk}']",
+    )
+    for elem in elements:
+        assert (
+            elem.find_element(By.CLASS_NAME, "card-title").text == unpriced_product.name
+        )
+    price_input = elements[0].find_element(By.CLASS_NAME, "numberinput")
+    chain = ActionChains(selenium)
+    chain.double_click(price_input).perform()
+    price_input.send_keys("237")
+    price_input = elements[1].find_element(By.CLASS_NAME, "numberinput")
+    chain = ActionChains(selenium)
+    chain.double_click(price_input).perform()
+    price_input.send_keys("401")
+
     # Don't add payment method
     # Save
     selenium.find_element(By.ID, "submit-id-submit").click()
@@ -93,7 +122,7 @@ def test_cashier_create_and_update_basket(  # noqa: PLR0915
     assert Basket.objects.count() == 1
     basket = Basket.objects.priced().first()
     assert basket.payment_method is None
-    assert basket.items.count() == 2
+    assert basket.items.count() == 4
     assert basket.items.get(product=products[0]).quantity == 2
     assert (
         basket.items.get(product=products[0]).unit_price_cents
@@ -104,6 +133,14 @@ def test_cashier_create_and_update_basket(  # noqa: PLR0915
         basket.items.get(product=products[1]).unit_price_cents
         == products[1].unit_price_cents
     )
+    unpriced_basket_items = basket.items.filter(product=unpriced_product).order_by(
+        "unit_price_cents",
+    )
+    assert len(unpriced_basket_items) == 2
+    assert unpriced_basket_items[0].quantity == 1
+    assert unpriced_basket_items[0].unit_price_cents == 237
+    assert unpriced_basket_items[1].quantity == 1
+    assert unpriced_basket_items[1].unit_price_cents == 401
 
     # Assert redirected to basket update view
     redirect_url = live_reverse(live_server, "purchase:update", pk=basket.pk)
@@ -141,6 +178,12 @@ def test_cashier_create_and_update_basket(  # noqa: PLR0915
     quantity = int(quantity_input.get_attribute("value"))
     assert quantity == 0
 
+    elements = selenium.find_elements(
+        By.CSS_SELECTOR,
+        f"[data-product-id='{unpriced_product.pk}']",
+    )
+    assert len(elements) == 2, "Unpriced products should be displayed"
+
     # Click on - on product 2
     displayed_product = displayed_products[1]
     displayed_product.find_element(By.CLASS_NAME, "btn-danger").click()
@@ -162,7 +205,7 @@ def test_cashier_create_and_update_basket(  # noqa: PLR0915
     assert Basket.objects.count() == 1
     basket = Basket.objects.priced().first()
     assert basket.payment_method == payment_methods[1]
-    assert basket.items.count() == 2
+    assert basket.items.count() == 4
     assert basket.items.get(product=products[0]).quantity == 2
     assert (
         basket.items.get(product=products[0]).unit_price_cents
@@ -173,6 +216,14 @@ def test_cashier_create_and_update_basket(  # noqa: PLR0915
         basket.items.get(product=products[1]).unit_price_cents
         == products[1].unit_price_cents
     )
+    unpriced_basket_items = basket.items.filter(product=unpriced_product).order_by(
+        "unit_price_cents",
+    )
+    assert len(unpriced_basket_items) == 2
+    assert unpriced_basket_items[0].quantity == 1
+    assert unpriced_basket_items[0].unit_price_cents == 237
+    assert unpriced_basket_items[1].quantity == 1
+    assert unpriced_basket_items[1].unit_price_cents == 401
 
     # Assert redirected to same view
     redirect_url = live_reverse(live_server, "purchase:update", pk=basket.pk)

src/purchase/urls.py

@@ -1,6 +1,7 @@
 from django.urls import path
 
 from purchase.views import delete_basket, list_baskets, new_basket, update_basket
+from purchase.views.basket import additional_unpriced_product
 from purchase.views.reports import by_hour_plot_view, products_plots_view, reports
 
 app_name = "purchase"
@@ -9,6 +10,11 @@ urlpatterns = [
     path("new/", new_basket, name="new"),
     path("<int:pk>/update/", update_basket, name="update"),
     path("<int:pk>/delete/", delete_basket, name="delete"),
+    path(
+        "additional_unpriced_product/",
+        additional_unpriced_product,
+        name="additional_unpriced_product",
+    ),
     path("reports/", reports, name="reports"),
     # plots
     path("reports/products_plots/", products_plots_view, name="products_plots"),

src/purchase/views/basket.py

@@ -1,25 +1,33 @@
+import logging
+
 from django.contrib import messages
 from django.contrib.auth.decorators import permission_required
+from django.core.handlers.wsgi import WSGIRequest
 from django.http import HttpRequest, HttpResponse
-from django.shortcuts import get_object_or_404, redirect
+from django.shortcuts import get_object_or_404, redirect, render
 from django.template.response import TemplateResponse
 from django.urls import reverse
+from django.utils.datastructures import MultiValueDict
 from django.utils.translation import gettext_lazy as _
 from django.views.decorators.http import condition, require_http_methods
+from django_htmx.http import trigger_client_event
 
-from purchase.forms import BasketForm
+from purchase.forms import UNPRICED_PREFIX, BasketForm
-from purchase.models import Basket, reports_etag, reports_last_modified
+from purchase.models import Basket, Product, reports_etag, reports_last_modified
+
+logger = logging.getLogger(__name__)
 
 
 @require_http_methods(["GET", "POST"])
 @permission_required("purchase.add_basket")
-def new_basket(request: HttpRequest) -> HttpResponse:
+def new_basket(request: WSGIRequest) -> HttpResponse:
     if request.method == "POST":
         form = BasketForm(request.POST)
         if form.is_valid():
-            instance = form.save()
+            basket = form.save()
+            update_with_unpriced_products(basket, request.POST)
             if request.user.has_perm("purchase.change_basket"):
-                url = instance.get_absolute_url()
+                url = basket.get_absolute_url()
             else:
                 url = reverse("purchase:new")
             messages.success(request, _("Successfully created basket."))
@@ -27,26 +35,61 @@ def new_basket(request: HttpRequest) -> HttpResponse:
     else:
         form = BasketForm()
 
-    return TemplateResponse(request, "purchase/basket_form.html", {"form": form})
+    return TemplateResponse(
+        request,
+        "purchase/basket_form.html",
+        {"form": form, "products": Product.objects.with_no_fixed_price()},
+    )
+
+
+def update_with_unpriced_products(basket: Basket, post_data: MultiValueDict):
+    no_fixed_price = {
+        product.id: product for product in Product.objects.with_no_fixed_price()
+    }
+    basket.items.filter(product__in=no_fixed_price.values()).delete()
+    for product_id, product in no_fixed_price.items():
+        if prices := post_data.getlist(f"{UNPRICED_PREFIX}{product_id}"):
+            for price in prices:
+                basket.items.create(product=product, quantity=1, unit_price_cents=price)
 
 
 @require_http_methods(["GET", "POST"])
 @permission_required("purchase.change_basket")
-def update_basket(request: HttpRequest, pk: int) -> HttpResponse:
+def update_basket(request: WSGIRequest, pk: int) -> HttpResponse:
     basket = get_object_or_404(Basket.objects.priced(), pk=pk)
     if request.method == "POST":
         form = BasketForm(request.POST, instance=basket)
         if form.is_valid():
             basket = form.save()
+            update_with_unpriced_products(basket, request.POST)
             messages.success(request, _("Successfully updated basket."))
             return redirect(basket.get_absolute_url())
     else:
         form = BasketForm(instance=basket)
 
-    return TemplateResponse(
+    response = render(
         request,
         "purchase/basket_form.html",
-        {"form": form, "basket": basket},
+        {
+            "form": form,
+            "basket": basket,
+            "products": Product.objects.with_no_fixed_price(),
+        },
+    )
+    trigger_client_event(response, "load-unpriced", after="swap")
+    return response
+
+
+@require_http_methods(["GET"])
+def additional_unpriced_product(request: WSGIRequest) -> HttpResponse:
+    product_id = request.GET.get("product_to_add")
+    value = request.GET.get("value", 0)
+    product = get_object_or_404(Product.objects.with_no_fixed_price(), pk=product_id)
+    context = {"product": product, "value": value}
+    return render(
+        request,
+        "purchase/snippets/basket_unpriced_item.html",
+        context,
     )