imageservice: Factorize Get, Update and Create Extract method

They all use the same Extract() implementation, so we can
implement it for a commonResult structure and define all 3
structures as commonResult.

Signed-off-by: Samuel Ortiz <[email protected]>

Author: Samuel Ortiz

openstack/imageservice/v2/images/results.go

@@ -66,13 +66,12 @@ type Image struct {
 	Properties map[string]string
 }
 
-// CreateResult model
-type CreateResult struct {
+type commonResult struct {
 	gophercloud.Result
 }
 
-// Extract build CreateResults from imput Image
-func (c CreateResult) Extract() (*Image, error) {
+// Extract interprets any commonResult as an Image.
+func (c commonResult) Extract() (*Image, error) {
 	if c.Err != nil {
 		return nil, c.Err
 	}
@@ -82,43 +81,26 @@ func (c CreateResult) Extract() (*Image, error) {
 	return image, err
 }
 
-//DeleteResult model
-type DeleteResult struct {
-	gophercloud.Result
+// CreateResult represents the result of a Create operation
+type CreateResult struct {
+	commonResult
 }
 
-// GetResult model
-type GetResult struct {
-	gophercloud.Result
+// UpdateResult represents the result of an Update operation
+type UpdateResult struct {
+	commonResult
 }
 
-// Extract builds GetResult
-func (c GetResult) Extract() (*Image, error) {
-	if c.Err != nil {
-		return nil, c.Err
-	}
-	var image *Image
-
-	err := mapstructure.Decode(c.Result.Body, &image)
-	return image, err
+// GetResult represents the result of a Get operation
+type GetResult struct {
+	commonResult
 }
 
-// UpdateResult model
-type UpdateResult struct {
+//DeleteResult model
+type DeleteResult struct {
 	gophercloud.Result
 }
 
-// Extract builds UpdateResult
-func (u UpdateResult) Extract() (*Image, error) {
-	if u.Err != nil {
-		return nil, u.Err
-	}
-	var image *Image
-
-	err := mapstructure.Decode(u.Result.Body, &image)
-	return image, err
-}
-
 // PutImageDataResult is model put image respose
 type PutImageDataResult struct {
 	gophercloud.Result