product variant id

repositories/productRepository.go

@@ -56,6 +56,9 @@ type ProductRepository interface {
 	UpdateProductPricing(productid int, retailprice, productcost, taxpercent float64) error
 	UpdateProductCategory(productid, categoryid, subcategoryid int) error
 	UpdateProductVariant(productid, variantid int) error
+	AddProductVariant(v models.Productvariant) (models.Productvariant, error)
+	RemoveProductVariant(tenantid, variantid int) error
+	VariantsForProducts(tenantid, locationid int, productids []int) (map[int][]models.Productvariant, error)
 }
 
 type productRepository struct {
@@ -1023,6 +1026,31 @@ func (r *productRepository) GetProductByVariant(tenantid, variantid, locationid,
 		return nil, err
 	}
 
+	// The sizes, attached to the products they belong to.
+	//
+	// This is what makes one call enough to draw the ordering screen: the app
+	// asks for the product it was tapped on and gets back the product plus every
+	// size hanging under it. A product with none comes back with an empty list,
+	// which is the answer that lets an order proceed.
+	//
+	// A failure here does not fail the request. The product and its price are
+	// the answer; the sizes are an enrichment, and returning the product without
+	// them beats returning nothing at all.
+	ids := make([]int, 0, len(data))
+	for i := range data {
+		ids = append(ids, data[i].Productid)
+	}
+	if byParent, vErr := r.VariantsForProducts(tenantid, locationid, ids); vErr == nil {
+		for i := range data {
+			data[i].Variantoptions = byParent[data[i].Productid]
+			if data[i].Variantoptions == nil {
+				// An explicit empty list, never a JSON null: a client that does
+				// `variantoptions.length` must not have to null-check first.
+				data[i].Variantoptions = []models.Productvariant{}
+			}
+		}
+	}
+
 	return data, nil
 }