Fix label marshalling

issues.go

@@ -76,13 +76,21 @@ func (i Issue) String() string {
 	return Stringify(i)
 }
 
+// Labels is a custom type with specific marshaling characteristics.
+type Labels []string
+
+// MarshalJSON implements the json.Marshaler interface.
+func (l *Labels) MarshalJSON() ([]byte, error) {
+	return []byte(strings.Join(*l, ",")), nil
+}
+
 // ListIssuesOptions represents the available ListIssues() options.
 //
 // GitLab API docs: http://doc.gitlab.com/ce/api/issues.html#list-issues
 type ListIssuesOptions struct {
 	ListOptions
 	State   string `url:"state,omitempty" json:"state,omitempty"`
-	Labels  []string `url:"labels,omitempty" json:"labels,omitempty"`
+	Labels  Labels `url:"labels,comma,omitempty" json:"labels,omitempty"`
 	OrderBy string `url:"order_by,omitempty" json:"order_by,omitempty"`
 	Sort    string `url:"sort,omitempty" json:"sort,omitempty"`
 }
@@ -113,7 +121,7 @@ type ListProjectIssuesOptions struct {
 	ListOptions
 	IID       int    `url:"iid,omitempty" json:"iid,omitempty"`
 	State     string `url:"state,omitempty" json:"state,omitempty"`
-	Labels    []string `url:"labels,omitempty" json:"labels,omitempty"`
+	Labels    Labels `url:"labels,comma,omitempty" json:"labels,omitempty"`
 	Milestone string `url:"milestone,omitempty" json:"milestone,omitempty"`
 	OrderBy   string `url:"order_by,omitempty" json:"order_by,omitempty"`
 	Sort      string `url:"sort,omitempty" json:"sort,omitempty"`
@@ -178,7 +186,7 @@ type CreateIssueOptions struct {
 	Description string `url:"description,omitempty" json:"description,omitempty"`
 	AssigneeID  int    `url:"assignee_id,omitempty" json:"assignee_id,omitempty"`
 	MilestoneID int    `url:"milestone_id,omitempty" json:"milestone_id,omitempty"`
-	Labels      []string `url:"labels,omitempty" json:"labels,omitempty"`
+	Labels      Labels `url:"labels,comma,omitempty" json:"labels,omitempty"`
 }
 
 // CreateIssue creates a new project issue.
@@ -193,11 +201,6 @@ func (s *IssuesService) CreateIssue(
 	}
 	u := fmt.Sprintf("projects/%s/issues", url.QueryEscape(project))
 
-	// This is needed to get a single, comma separated string
-	if len(opt.Labels) > 0 {
-		opt.Labels = []string{strings.Join(opt.Labels, ",")}
-	}
-
 	req, err := s.client.NewRequest("POST", u, opt)
 	if err != nil {
 		return nil, nil, err
@@ -222,7 +225,7 @@ type UpdateIssueOptions struct {
 	Description string `url:"description,omitempty" json:"description,omitempty"`
 	AssigneeID  int    `url:"assignee_id,omitempty" json:"assignee_id,omitempty"`
 	MilestoneID int    `url:"milestone_id,omitempty" json:"milestone_id,omitempty"`
-	Labels      []string `url:"labels,omitempty" json:"labels,omitempty"`
+	Labels      Labels `url:"labels,comma,omitempty" json:"labels,omitempty"`
 	StateEvent  string `url:"state_event,omitempty" json:"state_event,omitempty"`
 }
 
@@ -240,9 +243,6 @@ func (s *IssuesService) UpdateIssue(
 	}
 	u := fmt.Sprintf("projects/%s/issues/%d", url.QueryEscape(project), issue)
 
-	// This is needed to get a single, comma separated string
-	opt.Labels = []string{strings.Join(opt.Labels, ",")}
-
 	req, err := s.client.NewRequest("PUT", u, opt)
 	if err != nil {
 		return nil, nil, err