[FIX] website_sale: use image from first available variant if no default

Before this commit if a product template has no image, no image was
displayed in the website shop for the product

After this commit if a product template has no image, the image of the
first variant is displayed in the website shop

https://github.com/odoo/odoo/issues/52463

closes odoo/odoo#62440

X-original-commit: 643c8a9dce9455fe614f73ed97a793856e3608e7
Signed-off-by: Jérémy Kersten (jke) <jke@openerp.com>

addons/website_sale/models/product.py

@@ -320,6 +320,21 @@ class ProductTemplate(models.Model):
         """
         return self._create_product_variant(self._get_first_possible_combination(), log_warning)
 
+    def _get_image_holder(self):
+        """Returns the holder of the image to use as default representation.
+        If the product template has an image it is the product template,
+        otherwise if the product has variants it is the first variant
+
+        :return: this product template or the first product variant
+        :rtype: recordset of 'product.template' or recordset of 'product.product'
+        """
+        self.ensure_one()
+        if self.image_1920:
+            return self
+        variant = self.env['product.product'].browse(self._get_first_possible_variant_id())
+        # if the variant has no image anyway, spare some queries by using template
+        return variant if variant.image_variant_1920 else self
+
     def _get_current_company_fallback(self, **kwargs):
         """Override: if a website is set on the product or given, fallback to
         the company of the website. Otherwise use the one from parent method."""

addons/website_sale/tests/test_website_sale_image.py

@@ -256,3 +256,65 @@ class TestWebsiteSaleImage(odoo.tests.HttpCase):
         self.assertFalse(template_image.product_variant_id.id)
         self.assertFalse(variant_image.product_tmpl_id.id)
         self.assertEqual(variant_image.product_variant_id.id, product.id)
+
+    def test_02_image_holder(self):
+        f = io.BytesIO()
+        Image.new('RGB', (800, 500), '#FF0000').save(f, 'JPEG')
+        f.seek(0)
+        image = base64.b64encode(f.read())
+
+        # create the color attribute
+        product_attribute = self.env['product.attribute'].create({
+            'name': 'Beautiful Color',
+            'display_type': 'color',
+        })
+
+        # create the color attribute values
+        attr_values = self.env['product.attribute.value'].create([{
+            'name': 'Red',
+            'attribute_id': product_attribute.id,
+            'sequence': 1,
+        }, {
+            'name': 'Green',
+            'attribute_id': product_attribute.id,
+            'sequence': 2,
+        }, {
+            'name': 'Blue',
+            'attribute_id': product_attribute.id,
+            'sequence': 3,
+        }])
+
+        # create the template, without creating the variants
+        template = self.env['product.template'].with_context(create_product_product=True).create({
+            'name': 'Test subject',
+        })
+
+        # when there are no variants, the image must be obtained from the template
+        self.assertEqual(template, template._get_image_holder())
+
+        # set the color attribute and values on the template
+        line = self.env['product.template.attribute.line'].create([{
+            'attribute_id': product_attribute.id,
+            'product_tmpl_id': template.id,
+            'value_ids': [(6, 0, attr_values.ids)]
+        }])
+        value_red = line.product_template_value_ids[0]
+        product_red = template._get_variant_for_combination(value_red)
+        product_red.image_variant_1920 = image
+
+        value_green = line.product_template_value_ids[1]
+        product_green = template._get_variant_for_combination(value_green)
+        product_green.image_variant_1920 = image
+
+        # when there are no template image but there are variants, the image must be obtained from the first variant
+        self.assertEqual(product_red, template._get_image_holder())
+
+        product_red.toggle_active()
+
+        # but when some variants are not available, the image must be obtained from the first available variant
+        self.assertEqual(product_green, template._get_image_holder())
+
+        template.image_1920 = image
+
+        # when there is a template image, the image must be obtained from the template
+        self.assertEqual(template, template._get_image_holder())

addons/website_sale/views/templates.xml

@@ -261,7 +261,8 @@
             <div class="card-body p-1 oe_product_image">
                 <input type="hidden" name="csrf_token" t-att-value="request.csrf_token()" />
                 <a t-att-href="product_href" class="d-block h-100" itemprop="url">
-                    <span t-field="product.image_1920"
+                    <t t-set="image_holder" t-value="product._get_image_holder()"/>
+                    <span t-field="image_holder.image_1920"
                         t-options="{'widget': 'image', 'preview_image': 'image_1024' if product_image_big else 'image_256'}"
                         class="d-flex h-100 justify-content-center align-items-center"/>
                 </a>