diff --git a/models/issue.go b/models/issue.go
index d2a2b6a329b..99688f2ec9c 100644
--- a/models/issue.go
+++ b/models/issue.go
@@ -457,23 +457,6 @@ func (issue *Issue) IsPoster(uid int64) bool {
 	return issue.OriginalAuthorID == 0 && issue.PosterID == uid
 }
 
-func (issue *Issue) hasLabel(e db.Engine, labelID int64) bool {
-	return hasIssueLabel(e, issue.ID, labelID)
-}
-
-// HasLabel returns true if issue has been labeled by given ID.
-func (issue *Issue) HasLabel(labelID int64) bool {
-	return issue.hasLabel(db.GetEngine(db.DefaultContext), labelID)
-}
-
-func (issue *Issue) addLabel(ctx context.Context, label *Label, doer *user_model.User) error {
-	return newIssueLabel(ctx, issue, label, doer)
-}
-
-func (issue *Issue) addLabels(ctx context.Context, labels []*Label, doer *user_model.User) error {
-	return newIssueLabels(ctx, issue, labels, doer)
-}
-
 func (issue *Issue) getLabels(e db.Engine) (err error) {
 	if len(issue.Labels) > 0 {
 		return nil
@@ -486,17 +469,13 @@ func (issue *Issue) getLabels(e db.Engine) (err error) {
 	return nil
 }
 
-func (issue *Issue) removeLabel(ctx context.Context, doer *user_model.User, label *Label) error {
-	return deleteIssueLabel(ctx, issue, label, doer)
-}
-
-func (issue *Issue) clearLabels(ctx context.Context, doer *user_model.User) (err error) {
+func clearIssueLabels(ctx context.Context, issue *Issue, doer *user_model.User) (err error) {
 	if err = issue.getLabels(db.GetEngine(ctx)); err != nil {
 		return fmt.Errorf("getLabels: %v", err)
 	}
 
 	for i := range issue.Labels {
-		if err = issue.removeLabel(ctx, doer, issue.Labels[i]); err != nil {
+		if err = deleteIssueLabel(ctx, issue, issue.Labels[i], doer); err != nil {
 			return fmt.Errorf("removeLabel: %v", err)
 		}
 	}
@@ -504,9 +483,9 @@ func (issue *Issue) clearLabels(ctx context.Context, doer *user_model.User) (err
 	return nil
 }
 
-// ClearLabels removes all issue labels as the given user.
+// ClearIssueLabels removes all issue labels as the given user.
 // Triggers appropriate WebHooks, if any.
-func (issue *Issue) ClearLabels(doer *user_model.User) (err error) {
+func ClearIssueLabels(issue *Issue, doer *user_model.User) (err error) {
 	ctx, committer, err := db.TxContext()
 	if err != nil {
 		return err
@@ -527,7 +506,7 @@ func (issue *Issue) ClearLabels(doer *user_model.User) (err error) {
 		return ErrRepoLabelNotExist{}
 	}
 
-	if err = issue.clearLabels(ctx, doer); err != nil {
+	if err = clearIssueLabels(ctx, issue, doer); err != nil {
 		return err
 	}
 
@@ -552,9 +531,9 @@ func (ts labelSorter) Swap(i, j int) {
 	[]*Label(ts)[i], []*Label(ts)[j] = []*Label(ts)[j], []*Label(ts)[i]
 }
 
-// ReplaceLabels removes all current labels and add new labels to the issue.
+// ReplaceIssueLabels removes all current labels and add new labels to the issue.
 // Triggers appropriate WebHooks, if any.
-func (issue *Issue) ReplaceLabels(labels []*Label, doer *user_model.User) (err error) {
+func ReplaceIssueLabels(issue *Issue, labels []*Label, doer *user_model.User) (err error) {
 	ctx, committer, err := db.TxContext()
 	if err != nil {
 		return err
@@ -601,13 +580,13 @@ func (issue *Issue) ReplaceLabels(labels []*Label, doer *user_model.User) (err e
 	toRemove = append(toRemove, issue.Labels[removeIndex:]...)
 
 	if len(toAdd) > 0 {
-		if err = issue.addLabels(ctx, toAdd, doer); err != nil {
+		if err = newIssueLabels(ctx, issue, toAdd, doer); err != nil {
 			return fmt.Errorf("addLabels: %v", err)
 		}
 	}
 
 	for _, l := range toRemove {
-		if err = issue.removeLabel(ctx, doer, l); err != nil {
+		if err = deleteIssueLabel(ctx, issue, l, doer); err != nil {
 			return fmt.Errorf("removeLabel: %v", err)
 		}
 	}
@@ -636,7 +615,7 @@ func updateIssueCols(ctx context.Context, issue *Issue, cols ...string) error {
 	return nil
 }
 
-func (issue *Issue) changeStatus(ctx context.Context, doer *user_model.User, isClosed, isMergePull bool) (*Comment, error) {
+func changeIssueStatus(ctx context.Context, issue *Issue, doer *user_model.User, isClosed, isMergePull bool) (*Comment, error) {
 	// Reload the issue
 	currentIssue, err := getIssueByID(db.GetEngine(ctx), issue.ID)
 	if err != nil {
@@ -656,10 +635,10 @@ func (issue *Issue) changeStatus(ctx context.Context, doer *user_model.User, isC
 	}
 
 	issue.IsClosed = isClosed
-	return issue.doChangeStatus(ctx, doer, isMergePull)
+	return doChangeIssueStatus(ctx, issue, doer, isMergePull)
 }
 
-func (issue *Issue) doChangeStatus(ctx context.Context, doer *user_model.User, isMergePull bool) (*Comment, error) {
+func doChangeIssueStatus(ctx context.Context, issue *Issue, doer *user_model.User, isMergePull bool) (*Comment, error) {
 	e := db.GetEngine(ctx)
 	// Check for open dependencies
 	if issue.IsClosed && issue.Repo.IsDependenciesEnabledCtx(ctx) {
@@ -701,7 +680,7 @@ func (issue *Issue) doChangeStatus(ctx context.Context, doer *user_model.User, i
 		}
 	}
 
-	if err := issue.updateClosedNum(ctx); err != nil {
+	if err := updateIssueClosedNum(ctx, issue); err != nil {
 		return nil, err
 	}
 
@@ -721,8 +700,8 @@ func (issue *Issue) doChangeStatus(ctx context.Context, doer *user_model.User, i
 	})
 }
 
-// ChangeStatus changes issue status to open or closed.
-func (issue *Issue) ChangeStatus(doer *user_model.User, isClosed bool) (*Comment, error) {
+// ChangeIssueStatus changes issue status to open or closed.
+func ChangeIssueStatus(issue *Issue, doer *user_model.User, isClosed bool) (*Comment, error) {
 	ctx, committer, err := db.TxContext()
 	if err != nil {
 		return nil, err
@@ -736,7 +715,7 @@ func (issue *Issue) ChangeStatus(doer *user_model.User, isClosed bool) (*Comment
 		return nil, err
 	}
 
-	comment, err := issue.changeStatus(ctx, doer, isClosed, false)
+	comment, err := changeIssueStatus(ctx, issue, doer, isClosed, false)
 	if err != nil {
 		return nil, err
 	}
@@ -748,8 +727,8 @@ func (issue *Issue) ChangeStatus(doer *user_model.User, isClosed bool) (*Comment
 	return comment, nil
 }
 
-// ChangeTitle changes the title of this issue, as the given user.
-func (issue *Issue) ChangeTitle(doer *user_model.User, oldTitle string) (err error) {
+// ChangeIssueTitle changes the title of this issue, as the given user.
+func ChangeIssueTitle(issue *Issue, doer *user_model.User, oldTitle string) (err error) {
 	ctx, committer, err := db.TxContext()
 	if err != nil {
 		return err
@@ -782,8 +761,8 @@ func (issue *Issue) ChangeTitle(doer *user_model.User, oldTitle string) (err err
 	return committer.Commit()
 }
 
-// ChangeRef changes the branch of this issue, as the given user.
-func (issue *Issue) ChangeRef(doer *user_model.User, oldRef string) (err error) {
+// ChangeIssueRef changes the branch of this issue, as the given user.
+func ChangeIssueRef(issue *Issue, doer *user_model.User, oldRef string) (err error) {
 	ctx, committer, err := db.TxContext()
 	if err != nil {
 		return err
@@ -840,8 +819,8 @@ func AddDeletePRBranchComment(doer *user_model.User, repo *repo_model.Repository
 	return committer.Commit()
 }
 
-// UpdateAttachments update attachments by UUIDs for the issue
-func (issue *Issue) UpdateAttachments(uuids []string) (err error) {
+// UpdateIssueAttachments update attachments by UUIDs for the issue
+func UpdateIssueAttachments(issueID int64, uuids []string) (err error) {
 	ctx, committer, err := db.TxContext()
 	if err != nil {
 		return err
@@ -852,7 +831,7 @@ func (issue *Issue) UpdateAttachments(uuids []string) (err error) {
 		return fmt.Errorf("getAttachmentsByUUIDs [uuids: %v]: %v", uuids, err)
 	}
 	for i := 0; i < len(attachments); i++ {
-		attachments[i].IssueID = issue.ID
+		attachments[i].IssueID = issueID
 		if err := repo_model.UpdateAttachmentCtx(ctx, attachments[i]); err != nil {
 			return fmt.Errorf("update attachment [id: %d]: %v", attachments[i].ID, err)
 		}
@@ -860,8 +839,8 @@ func (issue *Issue) UpdateAttachments(uuids []string) (err error) {
 	return committer.Commit()
 }
 
-// ChangeContent changes issue content, as the given user.
-func (issue *Issue) ChangeContent(doer *user_model.User, content string) (err error) {
+// ChangeIssueContent changes issue content, as the given user.
+func ChangeIssueContent(issue *Issue, doer *user_model.User, content string) (err error) {
 	ctx, committer, err := db.TxContext()
 	if err != nil {
 		return err
@@ -1034,7 +1013,7 @@ func newIssue(ctx context.Context, doer *user_model.User, opts NewIssueOptions)
 				continue
 			}
 
-			if err = opts.Issue.addLabel(ctx, label, opts.Issue.Poster); err != nil {
+			if err = newIssueLabel(ctx, opts.Issue, label, opts.Issue.Poster); err != nil {
 				return fmt.Errorf("addLabel [id: %d]: %v", label.ID, err)
 			}
 		}
@@ -2011,7 +1990,7 @@ func UpdateIssueByAPI(issue *Issue, doer *user_model.User) (statusChangeComment
 	}
 
 	if currentIssue.IsClosed != issue.IsClosed {
-		statusChangeComment, err = issue.doChangeStatus(ctx, doer, false)
+		statusChangeComment, err = doChangeIssueStatus(ctx, issue, doer, false)
 		if err != nil {
 			return nil, false, err
 		}
@@ -2235,7 +2214,7 @@ func (issue *Issue) BlockingDependencies() ([]*DependencyInfo, error) {
 	return issue.getBlockingDependencies(db.GetEngine(db.DefaultContext))
 }
 
-func (issue *Issue) updateClosedNum(ctx context.Context) (err error) {
+func updateIssueClosedNum(ctx context.Context, issue *Issue) (err error) {
 	if issue.IsPull {
 		err = repoStatsCorrectNumClosed(ctx, issue.RepoID, true, "num_closed_pulls")
 	} else {
@@ -2245,9 +2224,9 @@ func (issue *Issue) updateClosedNum(ctx context.Context) (err error) {
 }
 
 // FindAndUpdateIssueMentions finds users mentioned in the given content string, and saves them in the database.
-func (issue *Issue) FindAndUpdateIssueMentions(ctx context.Context, doer *user_model.User, content string) (mentions []*user_model.User, err error) {
+func FindAndUpdateIssueMentions(ctx context.Context, issue *Issue, doer *user_model.User, content string) (mentions []*user_model.User, err error) {
 	rawMentions := references.FindAllMentionsMarkdown(content)
-	mentions, err = issue.ResolveMentionsByVisibility(ctx, doer, rawMentions)
+	mentions, err = ResolveIssueMentionsByVisibility(ctx, issue, doer, rawMentions)
 	if err != nil {
 		return nil, fmt.Errorf("UpdateIssueMentions [%d]: %v", issue.ID, err)
 	}
@@ -2257,9 +2236,9 @@ func (issue *Issue) FindAndUpdateIssueMentions(ctx context.Context, doer *user_m
 	return
 }
 
-// ResolveMentionsByVisibility returns the users mentioned in an issue, removing those that
+// ResolveIssueMentionsByVisibility returns the users mentioned in an issue, removing those that
 // don't have access to reading it. Teams are expanded into their users, but organizations are ignored.
-func (issue *Issue) ResolveMentionsByVisibility(ctx context.Context, doer *user_model.User, mentions []string) (users []*user_model.User, err error) {
+func ResolveIssueMentionsByVisibility(ctx context.Context, issue *Issue, doer *user_model.User, mentions []string) (users []*user_model.User, err error) {
 	if len(mentions) == 0 {
 		return
 	}
diff --git a/models/issue_assignees.go b/models/issue_assignees.go
index b3511f8b591..a91793f2f1c 100644
--- a/models/issue_assignees.go
+++ b/models/issue_assignees.go
@@ -92,15 +92,15 @@ func clearAssigneeByUserID(sess db.Engine, userID int64) (err error) {
 	return
 }
 
-// ToggleAssignee changes a user between assigned and not assigned for this issue, and make issue comment for it.
-func (issue *Issue) ToggleAssignee(doer *user_model.User, assigneeID int64) (removed bool, comment *Comment, err error) {
+// ToggleIssueAssignee changes a user between assigned and not assigned for this issue, and make issue comment for it.
+func ToggleIssueAssignee(issue *Issue, doer *user_model.User, assigneeID int64) (removed bool, comment *Comment, err error) {
 	ctx, committer, err := db.TxContext()
 	if err != nil {
 		return false, nil, err
 	}
 	defer committer.Close()
 
-	removed, comment, err = issue.toggleAssignee(ctx, doer, assigneeID, false)
+	removed, comment, err = toggleIssueAssignee(ctx, issue, doer, assigneeID, false)
 	if err != nil {
 		return false, nil, err
 	}
@@ -112,7 +112,7 @@ func (issue *Issue) ToggleAssignee(doer *user_model.User, assigneeID int64) (rem
 	return removed, comment, nil
 }
 
-func (issue *Issue) toggleAssignee(ctx context.Context, doer *user_model.User, assigneeID int64, isCreate bool) (removed bool, comment *Comment, err error) {
+func toggleIssueAssignee(ctx context.Context, issue *Issue, doer *user_model.User, assigneeID int64, isCreate bool) (removed bool, comment *Comment, err error) {
 	sess := db.GetEngine(ctx)
 	removed, err = toggleUserAssignee(sess, issue, assigneeID)
 	if err != nil {
diff --git a/models/issue_assignees_test.go b/models/issue_assignees_test.go
index dd9a42b572b..41a3ad86e39 100644
--- a/models/issue_assignees_test.go
+++ b/models/issue_assignees_test.go
@@ -23,17 +23,17 @@ func TestUpdateAssignee(t *testing.T) {
 	// Assign multiple users
 	user2, err := user_model.GetUserByID(2)
 	assert.NoError(t, err)
-	_, _, err = issue.ToggleAssignee(&user_model.User{ID: 1}, user2.ID)
+	_, _, err = ToggleIssueAssignee(issue, &user_model.User{ID: 1}, user2.ID)
 	assert.NoError(t, err)
 
 	user3, err := user_model.GetUserByID(3)
 	assert.NoError(t, err)
-	_, _, err = issue.ToggleAssignee(&user_model.User{ID: 1}, user3.ID)
+	_, _, err = ToggleIssueAssignee(issue, &user_model.User{ID: 1}, user3.ID)
 	assert.NoError(t, err)
 
 	user1, err := user_model.GetUserByID(1) // This user is already assigned (see the definition in fixtures), so running  UpdateAssignee should unassign him
 	assert.NoError(t, err)
-	_, _, err = issue.ToggleAssignee(&user_model.User{ID: 1}, user1.ID)
+	_, _, err = ToggleIssueAssignee(issue, &user_model.User{ID: 1}, user1.ID)
 	assert.NoError(t, err)
 
 	// Check if he got removed
diff --git a/models/issue_comment.go b/models/issue_comment.go
index 500ed6d0388..7fb013ae924 100644
--- a/models/issue_comment.go
+++ b/models/issue_comment.go
@@ -858,7 +858,7 @@ func updateCommentInfos(ctx context.Context, opts *CreateCommentOptions, comment
 			}
 		}
 	case CommentTypeReopen, CommentTypeClose:
-		if err = opts.Issue.updateClosedNum(ctx); err != nil {
+		if err = updateIssueClosedNum(ctx, opts.Issue); err != nil {
 			return err
 		}
 	}
diff --git a/models/issue_dependency_test.go b/models/issue_dependency_test.go
index 61215dedeff..1789de5dc04 100644
--- a/models/issue_dependency_test.go
+++ b/models/issue_dependency_test.go
@@ -48,7 +48,7 @@ func TestCreateIssueDependency(t *testing.T) {
 	assert.False(t, left)
 
 	// Close #2 and check again
-	_, err = issue2.ChangeStatus(user1, true)
+	_, err = ChangeIssueStatus(issue2, user1, true)
 	assert.NoError(t, err)
 
 	left, err = IssueNoDependenciesLeft(issue1)
diff --git a/models/issue_test.go b/models/issue_test.go
index 9afbce67c1f..71e0e8a2f7b 100644
--- a/models/issue_test.go
+++ b/models/issue_test.go
@@ -34,7 +34,7 @@ func TestIssue_ReplaceLabels(t *testing.T) {
 		for i, labelID := range labelIDs {
 			labels[i] = unittest.AssertExistsAndLoadBean(t, &Label{ID: labelID, RepoID: repo.ID}).(*Label)
 		}
-		assert.NoError(t, issue.ReplaceLabels(labels, doer))
+		assert.NoError(t, ReplaceIssueLabels(issue, labels, doer))
 		unittest.AssertCount(t, &IssueLabel{IssueID: issueID}, len(labelIDs))
 		for _, labelID := range labelIDs {
 			unittest.AssertExistsAndLoadBean(t, &IssueLabel{IssueID: issueID, LabelID: labelID})
@@ -116,7 +116,7 @@ func TestIssue_ClearLabels(t *testing.T) {
 		assert.NoError(t, unittest.PrepareTestDatabase())
 		issue := unittest.AssertExistsAndLoadBean(t, &Issue{ID: test.issueID}).(*Issue)
 		doer := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: test.doerID}).(*user_model.User)
-		assert.NoError(t, issue.ClearLabels(doer))
+		assert.NoError(t, ClearIssueLabels(issue, doer))
 		unittest.AssertNotExistsBean(t, &IssueLabel{IssueID: test.issueID})
 	}
 }
@@ -459,7 +459,7 @@ func TestIssue_ResolveMentions(t *testing.T) {
 		r := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{OwnerID: o.ID, LowerName: repo}).(*repo_model.Repository)
 		issue := &Issue{RepoID: r.ID}
 		d := unittest.AssertExistsAndLoadBean(t, &user_model.User{LowerName: doer}).(*user_model.User)
-		resolved, err := issue.ResolveMentionsByVisibility(db.DefaultContext, d, mentions)
+		resolved, err := ResolveIssueMentionsByVisibility(db.DefaultContext, issue, d, mentions)
 		assert.NoError(t, err)
 		ids := make([]int64, len(resolved))
 		for i, user := range resolved {
diff --git a/models/issue_xref_test.go b/models/issue_xref_test.go
index 1deeb44ad5e..1ae5fb360f0 100644
--- a/models/issue_xref_test.go
+++ b/models/issue_xref_test.go
@@ -83,7 +83,7 @@ func TestXRef_NeuterCrossReferences(t *testing.T) {
 
 	d := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2}).(*user_model.User)
 	i.Title = "title2, no mentions"
-	assert.NoError(t, i.ChangeTitle(d, title))
+	assert.NoError(t, ChangeIssueTitle(i, d, title))
 
 	ref = unittest.AssertExistsAndLoadBean(t, &Comment{IssueID: itarget.ID, RefIssueID: i.ID, RefCommentID: 0}).(*Comment)
 	assert.Equal(t, CommentTypeIssueRef, ref.Type)
@@ -98,7 +98,7 @@ func TestXRef_ResolveCrossReferences(t *testing.T) {
 	i1 := testCreateIssue(t, 1, 2, "title1", "content1", false)
 	i2 := testCreateIssue(t, 1, 2, "title2", "content2", false)
 	i3 := testCreateIssue(t, 1, 2, "title3", "content3", false)
-	_, err := i3.ChangeStatus(d, true)
+	_, err := ChangeIssueStatus(i3, d, true)
 	assert.NoError(t, err)
 
 	pr := testCreatePR(t, 1, 2, "titlepr", fmt.Sprintf("closes #%d", i1.Index))
diff --git a/models/pull.go b/models/pull.go
index d6bfbbf09fc..863c8d708f8 100644
--- a/models/pull.go
+++ b/models/pull.go
@@ -420,7 +420,7 @@ func (pr *PullRequest) SetMerged() (bool, error) {
 		return false, err
 	}
 
-	if _, err := pr.Issue.changeStatus(ctx, pr.Merger, true, true); err != nil {
+	if _, err := changeIssueStatus(ctx, pr.Issue, pr.Merger, true, true); err != nil {
 		return false, fmt.Errorf("Issue.changeStatus: %v", err)
 	}
 
diff --git a/routers/api/v1/repo/pull.go b/routers/api/v1/repo/pull.go
index ba3c42d9d71..1618c74fbc1 100644
--- a/routers/api/v1/repo/pull.go
+++ b/routers/api/v1/repo/pull.go
@@ -560,7 +560,7 @@ func EditPullRequest(ctx *context.APIContext) {
 			labels = append(labels, orgLabels...)
 		}
 
-		if err = issue.ReplaceLabels(labels, ctx.Doer); err != nil {
+		if err = models.ReplaceIssueLabels(issue, labels, ctx.Doer); err != nil {
 			ctx.Error(http.StatusInternalServerError, "ReplaceLabelsError", err)
 			return
 		}
diff --git a/routers/web/repo/issue.go b/routers/web/repo/issue.go
index 5af91c8e5fe..c50e773e99b 100644
--- a/routers/web/repo/issue.go
+++ b/routers/web/repo/issue.go
@@ -2595,7 +2595,7 @@ func updateAttachments(item interface{}, files []string) error {
 	if len(files) > 0 {
 		switch content := item.(type) {
 		case *models.Issue:
-			err = content.UpdateAttachments(files)
+			err = models.UpdateIssueAttachments(content.ID, files)
 		case *models.Comment:
 			err = content.UpdateAttachments(files)
 		default:
diff --git a/routers/web/repo/issue_label.go b/routers/web/repo/issue_label.go
index 289e870bb1c..887bbc115f0 100644
--- a/routers/web/repo/issue_label.go
+++ b/routers/web/repo/issue_label.go
@@ -191,7 +191,7 @@ func UpdateIssueLabel(ctx *context.Context) {
 			// detach if any issues already have label, otherwise attach
 			action = "attach"
 			for _, issue := range issues {
-				if issue.HasLabel(label.ID) {
+				if models.HasIssueLabel(issue.ID, label.ID) {
 					action = "detach"
 					break
 				}
diff --git a/services/comments/comments.go b/services/comments/comments.go
index 6f63060c45f..c1b3ab73c9f 100644
--- a/services/comments/comments.go
+++ b/services/comments/comments.go
@@ -28,7 +28,7 @@ func CreateIssueComment(doer *user_model.User, repo *repo_model.Repository, issu
 		return nil, err
 	}
 
-	mentions, err := issue.FindAndUpdateIssueMentions(db.DefaultContext, doer, comment.Content)
+	mentions, err := models.FindAndUpdateIssueMentions(db.DefaultContext, issue, doer, comment.Content)
 	if err != nil {
 		return nil, err
 	}
diff --git a/services/issue/assignee.go b/services/issue/assignee.go
index 86d653dfa60..479c9cbb138 100644
--- a/services/issue/assignee.go
+++ b/services/issue/assignee.go
@@ -42,7 +42,7 @@ func DeleteNotPassedAssignee(issue *models.Issue, doer *user_model.User, assigne
 
 // ToggleAssignee changes a user between assigned and not assigned for this issue, and make issue comment for it.
 func ToggleAssignee(issue *models.Issue, doer *user_model.User, assigneeID int64) (removed bool, comment *models.Comment, err error) {
-	removed, comment, err = issue.ToggleAssignee(doer, assigneeID)
+	removed, comment, err = models.ToggleIssueAssignee(issue, doer, assigneeID)
 	if err != nil {
 		return
 	}
diff --git a/services/issue/content.go b/services/issue/content.go
index 6d7883090b0..a60878479b3 100644
--- a/services/issue/content.go
+++ b/services/issue/content.go
@@ -14,7 +14,7 @@ import (
 func ChangeContent(issue *models.Issue, doer *user_model.User, content string) (err error) {
 	oldContent := issue.Content
 
-	if err := issue.ChangeContent(doer, content); err != nil {
+	if err := models.ChangeIssueContent(issue, doer, content); err != nil {
 		return err
 	}
 
diff --git a/services/issue/issue.go b/services/issue/issue.go
index 6e5e4bfd373..6bc39599793 100644
--- a/services/issue/issue.go
+++ b/services/issue/issue.go
@@ -28,7 +28,7 @@ func NewIssue(repo *repo_model.Repository, issue *models.Issue, labelIDs []int64
 		}
 	}
 
-	mentions, err := issue.FindAndUpdateIssueMentions(db.DefaultContext, issue.Poster, issue.Content)
+	mentions, err := models.FindAndUpdateIssueMentions(db.DefaultContext, issue, issue.Poster, issue.Content)
 	if err != nil {
 		return err
 	}
@@ -49,7 +49,7 @@ func ChangeTitle(issue *models.Issue, doer *user_model.User, title string) (err
 	oldTitle := issue.Title
 	issue.Title = title
 
-	if err = issue.ChangeTitle(doer, oldTitle); err != nil {
+	if err = models.ChangeIssueTitle(issue, doer, oldTitle); err != nil {
 		return
 	}
 
@@ -63,7 +63,7 @@ func ChangeIssueRef(issue *models.Issue, doer *user_model.User, ref string) erro
 	oldRef := issue.Ref
 	issue.Ref = ref
 
-	if err := issue.ChangeRef(doer, oldRef); err != nil {
+	if err := models.ChangeIssueRef(issue, doer, oldRef); err != nil {
 		return err
 	}
 
diff --git a/services/issue/label.go b/services/issue/label.go
index 96df7ed345b..9971be326c6 100644
--- a/services/issue/label.go
+++ b/services/issue/label.go
@@ -12,7 +12,7 @@ import (
 
 // ClearLabels clears all of an issue's labels
 func ClearLabels(issue *models.Issue, doer *user_model.User) (err error) {
-	if err = issue.ClearLabels(doer); err != nil {
+	if err = models.ClearIssueLabels(issue, doer); err != nil {
 		return
 	}
 
@@ -73,7 +73,7 @@ func ReplaceLabels(issue *models.Issue, doer *user_model.User, labels []*models.
 		return err
 	}
 
-	if err := issue.ReplaceLabels(labels, doer); err != nil {
+	if err := models.ReplaceIssueLabels(issue, labels, doer); err != nil {
 		return err
 	}
 
diff --git a/services/issue/status.go b/services/issue/status.go
index 64fbccd26a8..1af4508b09f 100644
--- a/services/issue/status.go
+++ b/services/issue/status.go
@@ -14,7 +14,7 @@ import (
 
 // ChangeStatus changes issue status to open or closed.
 func ChangeStatus(issue *models.Issue, doer *user_model.User, closed bool) error {
-	comment, err := issue.ChangeStatus(doer, closed)
+	comment, err := models.ChangeIssueStatus(issue, doer, closed)
 	if err != nil {
 		if models.IsErrDependenciesLeft(err) && closed {
 			if err := models.FinishIssueStopwatchIfPossible(db.DefaultContext, doer, issue); err != nil {
diff --git a/services/pull/pull.go b/services/pull/pull.go
index 7a746d937fa..562912cab9c 100644
--- a/services/pull/pull.go
+++ b/services/pull/pull.go
@@ -69,7 +69,7 @@ func NewPullRequest(ctx context.Context, repo *repo_model.Repository, pull *mode
 		return err
 	}
 
-	mentions, err := pull.FindAndUpdateIssueMentions(ctx, pull.Poster, pull.Content)
+	mentions, err := models.FindAndUpdateIssueMentions(ctx, pull, pull.Poster, pull.Content)
 	if err != nil {
 		return err
 	}
diff --git a/services/pull/review.go b/services/pull/review.go
index 7f9797579a5..111e959a87b 100644
--- a/services/pull/review.go
+++ b/services/pull/review.go
@@ -61,7 +61,7 @@ func CreateCodeComment(ctx context.Context, doer *user_model.User, gitRepo *git.
 			return nil, err
 		}
 
-		mentions, err := issue.FindAndUpdateIssueMentions(ctx, doer, comment.Content)
+		mentions, err := models.FindAndUpdateIssueMentions(ctx, issue, doer, comment.Content)
 		if err != nil {
 			return nil, err
 		}
@@ -248,7 +248,7 @@ func SubmitReview(ctx context.Context, doer *user_model.User, gitRepo *git.Repos
 		return nil, nil, err
 	}
 
-	mentions, err := issue.FindAndUpdateIssueMentions(ctx, doer, comm.Content)
+	mentions, err := models.FindAndUpdateIssueMentions(ctx, issue, doer, comm.Content)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -258,7 +258,7 @@ func SubmitReview(ctx context.Context, doer *user_model.User, gitRepo *git.Repos
 	for _, lines := range review.CodeComments {
 		for _, comments := range lines {
 			for _, codeComment := range comments {
-				mentions, err := issue.FindAndUpdateIssueMentions(ctx, doer, codeComment.Content)
+				mentions, err := models.FindAndUpdateIssueMentions(ctx, issue, doer, codeComment.Content)
 				if err != nil {
 					return nil, nil, err
 				}