fix: support uint query params (#190)

* fix: support uint query params

The driver did accept query parameters of type `uint`, but the
underlying Spanner client would not accept these. `uint` query
parameters therefore first need to be converted to `int64` and then sent
to the Spanner client.

* chore: fix imports

driver_with_mockserver_test.go

@@ -478,7 +478,7 @@ func TestQueryWithAllTypes(t *testing.T) {
 		true,
 		"test",
 		[]byte("testbytes"),
-		int64(5),
+		uint(5),
 		3.14,
 		numeric("6.626"),
 		civil.Date{Year: 2021, Month: 7, Day: 21},

stmt.go

@@ -78,11 +78,37 @@ func prepareSpannerStmt(q string, args []driver.NamedValue) (spanner.Statement,
 		if name == "" {
 			name = names[i]
 		}
-		ss.Params[name] = v.Value
+		ss.Params[name] = convertParam(v.Value)
 	}
 	return ss, nil
 }
 
+func convertParam(v driver.Value) driver.Value {
+	switch v.(type) {
+	default:
+		return v
+	case uint:
+		return int64(v.(uint))
+	case []uint:
+		vu := v.([]uint)
+		res := make([]int64, len(vu))
+		for i, val := range vu {
+			res[i] = int64(val)
+		}
+		return res
+	case *uint:
+		vi := int64(*v.(*uint))
+		return &vi
+	case *[]uint:
+		vu := v.(*[]uint)
+		res := make([]int64, len(*vu))
+		for i, val := range *vu {
+			res[i] = int64(val)
+		}
+		return &res
+	}
+}
+
 type result struct {
 	rowsAffected int64
 }