add fill struct method

pkg/util/aws/instance.go

@@ -390,7 +390,8 @@ func (self *SRegion) GetInstances(zoneId string, ids []string, offset int, limit
 	instances := []SInstance{}
 	for _, reservation := range res.Reservations {
 		for _, instance := range reservation.Instances {
-			instanceType, err := self.GetInstanceType(StrVal(instance.InstanceType))
+			FillZero(instance)
+			instanceType, err := self.GetInstanceType(*instance.InstanceType)
 			if err != nil {
 				return nil, 0 , err
 			}
@@ -415,9 +416,9 @@ func (self *SRegion) GetInstances(zoneId string, ids []string, offset int, limit
 			var networkInterfaces SNetworkInterfaces
 			for _, n := range instance.NetworkInterfaces {
 				i := SNetworkInterface{
-					MacAddress:         StrVal(n.MacAddress),
-					NetworkInterfaceId: StrVal(n.NetworkInterfaceId),
-					PrimaryIpAddress:   StrVal(n.PrivateIpAddress),
+					MacAddress:         *n.MacAddress,
+					NetworkInterfaceId: *n.NetworkInterfaceId,
+					PrimaryIpAddress:   *n.PrivateIpAddress,
 				}
 				networkInterfaces.NetworkInterface = append(networkInterfaces.NetworkInterface, i)
 			}

pkg/util/aws/utils.go

@@ -3,6 +3,7 @@ package aws
 import (
 	"fmt"
 	"net"
+	"reflect"
 	"strings"
 
 	"github.com/aws/aws-sdk-go/service/ec2"
@@ -311,4 +312,41 @@ func YunionSecRuleToAws(rule secrules.SecurityRule) ([]ec2.IpPermission, error)
 	}
 
 	return permissions, nil
+}
+
+
+// fill a pointer struct with zero value.
+func FillZero(i interface{}) error {
+	V := reflect.Indirect(reflect.ValueOf(i))
+
+	if !V.CanSet() {
+		return fmt.Errorf("input is not addressable: %#v", i)
+	}
+
+	if V.Kind() != reflect.Struct {
+		return fmt.Errorf("only accept struct type")
+	}
+
+	for i := 0; i < V.NumField(); i++ {
+		field := V.Field(i)
+
+		if field.Kind() == reflect.Ptr && field.IsNil() {
+			if field.CanSet() {
+				field.Set(reflect.New(field.Type().Elem()))
+			}
+		}
+
+		vField := reflect.Indirect(field)
+		switch vField.Kind() {
+		case reflect.Map:
+			vField.Set(reflect.MakeMap(vField.Type()))
+		case reflect.Struct:
+			err := FillZero(field.Interface())
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
 }