variants as a single product

repositories/productRepository.go

@@ -59,6 +59,7 @@ type ProductRepository interface {
 	AddProductVariant(v models.Productvariant) (models.Productvariant, error)
 	RemoveProductVariant(tenantid, variantid int) error
 	VariantsForProducts(tenantid, locationid int, productids []int) (map[int][]models.Productvariant, error)
+	VariantChildIDs(tenantid int) (map[int]bool, error)
 }
 
 type productRepository struct {
@@ -1042,12 +1043,40 @@ func (r *productRepository) GetProductByVariant(tenantid, variantid, locationid,
 	}
 	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 {
+			children := byParent[data[i].Productid]
+			if len(children) == 0 {
 				// An explicit empty list, never a JSON null: a client that does
-				// `variantoptions.length` must not have to null-check first.
+				// `variantoptions.length` must not have to null-check first, and
+				// an empty list is the complete answer “order this one directly”.
 				data[i].Variantoptions = []models.Productvariant{}
+				continue
 			}
+
+			// The product being looked at is one of its own sizes.
+			//
+			// Without this the picker on “Aachi Baby Fryums 100g” offers 500g and
+			// 1kg and not the 100g the shopper is already reading — so the size
+			// they came for is the one option they cannot choose, and there is no
+			// way back to it once they move off. Every screen in the group now
+			// shows the same complete list.
+			//
+			// Built from the product row already in hand rather than by another
+			// query: it carries the effective price and the live balance this
+			// query just computed, so the entry cannot disagree with the row it
+			// came from.
+			self := models.Productvariant{
+				Tenantid:           data[i].Tenantid,
+				Productid:          data[i].Productid,
+				Variantproductid:   data[i].Productid,
+				Variantname:        variantLabelFor(data[i]),
+				Status:             "Active",
+				Variantproductname: data[i].Productname,
+				Variantprice:       data[i].Price,
+				Variantstock:       data[i].Productstock,
+				Variantunitvalue:   data[i].Unitvalue,
+				Variantproductunit: data[i].Productunit,
+			}
+			data[i].Variantoptions = append([]models.Productvariant{self}, children...)
 		}
 	}