product variant id

main.go

@@ -133,6 +133,45 @@ func main() {
 		log.Println("productlocations.publishedat added and backfilled (one time)")
 	}
 
+	// A key generator for productvariants.variantid.
+	//
+	// The column is NOT NULL with no default and no identity, unlike
+	// products.productid next door which is an identity column. So every insert
+	// had to supply the id by hand, and GORM does not — it sent nothing and
+	// Postgres refused the row with a not-null violation. That is why variants
+	// could never be attached to a product: the write could not land at all.
+	//
+	// Guarded on the absence of a default rather than tracked as a migration
+	// version, matching the checks above: the question is answerable from the
+	// schema itself. The sequence starts above whatever ids are already there,
+	// so the two rows on production keep theirs.
+	var variantKeyed int64
+	if err := db.DB.Raw(`
+		SELECT COUNT(1) FROM information_schema.columns
+		WHERE table_name = 'productvariants' AND column_name = 'variantid'
+		  AND (column_default IS NOT NULL OR is_identity = 'YES')`).
+		Scan(&variantKeyed).Error; err != nil {
+		log.Fatal("could not check productvariants.variantid:", err)
+	}
+	if variantKeyed == 0 {
+		if err := db.DB.Exec(`
+			CREATE SEQUENCE IF NOT EXISTS productvariants_variantid_seq
+			START WITH 1 OWNED BY productvariants.variantid`).Error; err != nil {
+			log.Fatal("could not create productvariants_variantid_seq:", err)
+		}
+		if err := db.DB.Exec(`
+			SELECT setval('productvariants_variantid_seq',
+			              COALESCE((SELECT MAX(variantid) FROM productvariants), 0) + 1, false)`).Error; err != nil {
+			log.Fatal("could not position productvariants_variantid_seq:", err)
+		}
+		if err := db.DB.Exec(`
+			ALTER TABLE productvariants
+			ALTER COLUMN variantid SET DEFAULT nextval('productvariants_variantid_seq')`).Error; err != nil {
+			log.Fatal("could not default productvariants.variantid:", err)
+		}
+		log.Println("productvariants.variantid given a key generator (one time)")
+	}
+
 	// The catalogue's own stable key for an imported product.
 	//
 	// `catalogueid` was never able to be this. The catalogue is rebuilt by