New webhook trigger for receiving Pull Request review requests (#24481)

close https://github.com/go-gitea/gitea/issues/16321

Provided a webhook trigger for requesting someone to review the Pull
Request.

Some modifications have been made to the returned `PullRequestPayload`
based on the GitHub webhook settings, including:
- add a description of the current reviewer object as
`RequestedReviewer` .
- setting the action to either **review_requested** or
**review_request_removed** based on the operation.
- adding the `RequestedReviewers` field to the issues_model.PullRequest.
This field will be loaded into the PullRequest through
`LoadRequestedReviewers()` when `ToAPIPullRequest` is called.

After the Pull Request is merged, I will supplement the relevant
documentation.

21 files changed, 304 insertions, 116 deletions

diff --git a/models/issues/pull.go b/models/issues/pull.go
index 218a265741..3f37d8d243 100644
--- a/models/issues/pull.go
+++ b/models/issues/pull.go
@@ -175,9 +175,10 @@ type PullRequest struct {
 
 	ChangedProtectedFiles []string `xorm:"TEXT JSON"`
 
-	IssueID int64  `xorm:"INDEX"`
-	Issue   *Issue `xorm:"-"`
-	Index   int64
+	IssueID            int64  `xorm:"INDEX"`
+	Issue              *Issue `xorm:"-"`
+	Index              int64
+	RequestedReviewers []*user_model.User `xorm:"-"`
 
 	HeadRepoID          int64                  `xorm:"INDEX"`
 	HeadRepo            *repo_model.Repository `xorm:"-"`
@@ -302,6 +303,29 @@ func (pr *PullRequest) LoadHeadRepo(ctx context.Context) (err error) {
 	return nil
 }
 
+// LoadRequestedReviewers loads the requested reviewers.
+func (pr *PullRequest) LoadRequestedReviewers(ctx context.Context) error {
+	if len(pr.RequestedReviewers) > 0 {
+		return nil
+	}
+
+	reviews, err := GetReviewsByIssueID(pr.Issue.ID)
+	if err != nil {
+		return err
+	}
+
+	if len(reviews) > 0 {
+		err = LoadReviewers(ctx, reviews)
+		if err != nil {
+			return err
+		}
+		for _, review := range reviews {
+			pr.RequestedReviewers = append(pr.RequestedReviewers, review.Reviewer)
+		}
+	}
+	return nil
+}
+
 // LoadBaseRepo loads the target repository. ErrRepoNotExist may be returned.
 func (pr *PullRequest) LoadBaseRepo(ctx context.Context) (err error) {
 	if pr.BaseRepo != nil {
diff --git a/models/issues/pull_test.go b/models/issues/pull_test.go
index 0b06095213..7a183ac312 100644
--- a/models/issues/pull_test.go
+++ b/models/issues/pull_test.go
@@ -9,6 +9,7 @@ import (
 	"code.gitea.io/gitea/models/db"
 	issues_model "code.gitea.io/gitea/models/issues"
 	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -74,6 +75,34 @@ func TestPullRequestsNewest(t *testing.T) {
 	}
 }
 
+func TestLoadRequestedReviewers(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	pull := unittest.AssertExistsAndLoadBean(t, &issues_model.PullRequest{ID: 1})
+	assert.NoError(t, pull.LoadIssue(db.DefaultContext))
+	issue := pull.Issue
+	assert.NoError(t, issue.LoadRepo(db.DefaultContext))
+	assert.Len(t, pull.RequestedReviewers, 0)
+
+	user1, err := user_model.GetUserByID(db.DefaultContext, 1)
+	assert.NoError(t, err)
+
+	comment, err := issues_model.AddReviewRequest(issue, user1, &user_model.User{})
+	assert.NoError(t, err)
+	assert.NotNil(t, comment)
+
+	assert.NoError(t, pull.LoadRequestedReviewers(db.DefaultContext))
+	assert.Len(t, pull.RequestedReviewers, 1)
+
+	comment, err = issues_model.RemoveReviewRequest(issue, user1, &user_model.User{})
+	assert.NoError(t, err)
+	assert.NotNil(t, comment)
+
+	pull.RequestedReviewers = nil
+	assert.NoError(t, pull.LoadRequestedReviewers(db.DefaultContext))
+	assert.Empty(t, pull.RequestedReviewers)
+}
+
 func TestPullRequestsOldest(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())
 	prs, count, err := issues_model.PullRequests(1, &issues_model.PullRequestsOptions{
diff --git a/models/issues/review.go b/models/issues/review.go
index ed30bce149..06cf132a48 100644
--- a/models/issues/review.go
+++ b/models/issues/review.go
@@ -162,6 +162,27 @@ func (r *Review) LoadReviewer(ctx context.Context) (err error) {
 	return err
 }
 
+// LoadReviewers loads reviewers
+func LoadReviewers(ctx context.Context, reviews []*Review) (err error) {
+	reviewerIds := make([]int64, len(reviews))
+	for i := 0; i < len(reviews); i++ {
+		reviewerIds[i] = reviews[i].ReviewerID
+	}
+	reviewers, err := user_model.GetPossibleUserByIDs(ctx, reviewerIds)
+	if err != nil {
+		return err
+	}
+
+	userMap := make(map[int64]*user_model.User, len(reviewers))
+	for _, reviewer := range reviewers {
+		userMap[reviewer.ID] = reviewer
+	}
+	for _, review := range reviews {
+		review.Reviewer = userMap[review.ReviewerID]
+	}
+	return nil
+}
+
 // LoadReviewerTeam loads reviewer team
 func (r *Review) LoadReviewerTeam(ctx context.Context) (err error) {
 	if r.ReviewerTeamID == 0 || r.ReviewerTeam != nil {
@@ -520,8 +541,8 @@ func GetReviews(ctx context.Context, opts *GetReviewOptions) ([]*Review, error)
 	return reviews, sess.Find(&reviews)
 }
 
-// GetReviewersByIssueID gets the latest review of each reviewer for a pull request
-func GetReviewersByIssueID(issueID int64) ([]*Review, error) {
+// GetReviewsByIssueID gets the latest review of each reviewer for a pull request
+func GetReviewsByIssueID(issueID int64) ([]*Review, error) {
 	reviews := make([]*Review, 0, 10)
 
 	sess := db.GetEngine(db.DefaultContext)
diff --git a/models/issues/review_test.go b/models/issues/review_test.go
index 3221496577..0cb621812c 100644
--- a/models/issues/review_test.go
+++ b/models/issues/review_test.go
@@ -132,11 +132,22 @@ func TestGetReviewersByIssueID(t *testing.T) {
 			UpdatedUnix: 946684814,
 		})
 
-	allReviews, err := issues_model.GetReviewersByIssueID(issue.ID)
-	for _, reviewer := range allReviews {
-		assert.NoError(t, reviewer.LoadReviewer(db.DefaultContext))
+	allReviews, err := issues_model.GetReviewsByIssueID(issue.ID)
+	assert.NoError(t, err)
+	for _, review := range allReviews {
+		assert.NoError(t, review.LoadReviewer(db.DefaultContext))
 	}
+	if assert.Len(t, allReviews, 3) {
+		for i, review := range allReviews {
+			assert.Equal(t, expectedReviews[i].Reviewer, review.Reviewer)
+			assert.Equal(t, expectedReviews[i].Type, review.Type)
+			assert.Equal(t, expectedReviews[i].UpdatedUnix, review.UpdatedUnix)
+		}
+	}
+
+	allReviews, err = issues_model.GetReviewsByIssueID(issue.ID)
 	assert.NoError(t, err)
+	assert.NoError(t, issues_model.LoadReviewers(db.DefaultContext, allReviews))
 	if assert.Len(t, allReviews, 3) {
 		for i, review := range allReviews {
 			assert.Equal(t, expectedReviews[i].Reviewer, review.Reviewer)
diff --git a/models/user/user.go b/models/user/user.go
index 57b2117bb9..07d8177b6a 100644
--- a/models/user/user.go
+++ b/models/user/user.go
@@ -20,6 +20,7 @@ import (
 	"code.gitea.io/gitea/modules/auth/openid"
 	"code.gitea.io/gitea/modules/auth/password/hash"
 	"code.gitea.io/gitea/modules/base"
+	"code.gitea.io/gitea/modules/container"
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
@@ -910,6 +911,15 @@ func GetUserByID(ctx context.Context, id int64) (*User, error) {
 	return u, nil
 }
 
+// GetUserByIDs returns the user objects by given IDs if exists.
+func GetUserByIDs(ctx context.Context, ids []int64) ([]*User, error) {
+	users := make([]*User, 0, len(ids))
+	err := db.GetEngine(ctx).In("id", ids).
+		Table("user").
+		Find(&users)
+	return users, err
+}
+
 // GetPossibleUserByID returns the user if id > 0 or return system usrs if id < 0
 func GetPossibleUserByID(ctx context.Context, id int64) (*User, error) {
 	switch id {
@@ -924,6 +934,25 @@ func GetPossibleUserByID(ctx context.Context, id int64) (*User, error) {
 	}
 }
 
+// GetPossibleUserByIDs returns the users if id > 0 or return system users if id < 0
+func GetPossibleUserByIDs(ctx context.Context, ids []int64) ([]*User, error) {
+	uniqueIDs := container.SetOf(ids...)
+	users := make([]*User, 0, len(ids))
+	_ = uniqueIDs.Remove(0)
+	if uniqueIDs.Remove(-1) {
+		users = append(users, NewGhostUser())
+	}
+	if uniqueIDs.Remove(ActionsUserID) {
+		users = append(users, NewActionsUser())
+	}
+	res, err := GetUserByIDs(ctx, uniqueIDs.Values())
+	if err != nil {
+		return nil, err
+	}
+	users = append(users, res...)
+	return users, nil
+}
+
 // GetUserByNameCtx returns user by given name.
 func GetUserByName(ctx context.Context, name string) (*User, error) {
 	if len(name) == 0 {
diff --git a/models/webhook/webhook.go b/models/webhook/webhook.go
index e3f6b593d9..fc2bbed083 100644
--- a/models/webhook/webhook.go
+++ b/models/webhook/webhook.go
@@ -298,6 +298,12 @@ func (w *Webhook) HasPackageEvent() bool {
 		(w.ChooseEvents && w.HookEvents.Package)
 }
 
+// HasPullRequestReviewRequestEvent returns true if hook enabled pull request review request event.
+func (w *Webhook) HasPullRequestReviewRequestEvent() bool {
+	return w.SendEverything ||
+		(w.ChooseEvents && w.HookEvents.PullRequestReviewRequest)
+}
+
 // EventCheckers returns event checkers
 func (w *Webhook) EventCheckers() []struct {
 	Has  func() bool
@@ -329,6 +335,7 @@ func (w *Webhook) EventCheckers() []struct {
 		{w.HasRepositoryEvent, webhook_module.HookEventRepository},
 		{w.HasReleaseEvent, webhook_module.HookEventRelease},
 		{w.HasPackageEvent, webhook_module.HookEventPackage},
+		{w.HasPullRequestReviewRequestEvent, webhook_module.HookEventPullRequestReviewRequest},
 	}
 }
 
diff --git a/models/webhook/webhook_test.go b/models/webhook/webhook_test.go
index e05dcaba01..de6568c321 100644
--- a/models/webhook/webhook_test.go
+++ b/models/webhook/webhook_test.go
@@ -73,7 +73,7 @@ func TestWebhook_EventsArray(t *testing.T) {
 		"pull_request", "pull_request_assign", "pull_request_label", "pull_request_milestone",
 		"pull_request_comment", "pull_request_review_approved", "pull_request_review_rejected",
 		"pull_request_review_comment", "pull_request_sync", "wiki", "repository", "release",
-		"package",
+		"package", "pull_request_review_request",
 	},
 		(&Webhook{
 			HookEvent: &webhook_module.HookEvent{SendEverything: true},
diff --git a/modules/structs/hook.go b/modules/structs/hook.go
index df5da6790f..cd91d4bc46 100644
--- a/modules/structs/hook.go
+++ b/modules/structs/hook.go
@@ -342,6 +342,10 @@ const (
 	HookIssueDemilestoned HookIssueAction = "demilestoned"
 	// HookIssueReviewed is an issue action for when a pull request is reviewed
 	HookIssueReviewed HookIssueAction = "reviewed"
+	// HookIssueReviewRequested is an issue action for when a reviewer is requested for a pull request.
+	HookIssueReviewRequested HookIssueAction = "review_requested"
+	// HookIssueReviewRequestRemoved is an issue action for removing a review request to someone on a pull request.
+	HookIssueReviewRequestRemoved HookIssueAction = "review_request_removed"
 )
 
 // IssuePayload represents the payload information that is sent along with an issue event.
@@ -381,14 +385,15 @@ type ChangesPayload struct {
 
 // PullRequestPayload represents a payload information of pull request event.
 type PullRequestPayload struct {
-	Action      HookIssueAction `json:"action"`
-	Index       int64           `json:"number"`
-	Changes     *ChangesPayload `json:"changes,omitempty"`
-	PullRequest *PullRequest    `json:"pull_request"`
-	Repository  *Repository     `json:"repository"`
-	Sender      *User           `json:"sender"`
-	CommitID    string          `json:"commit_id"`
-	Review      *ReviewPayload  `json:"review"`
+	Action            HookIssueAction `json:"action"`
+	Index             int64           `json:"number"`
+	Changes           *ChangesPayload `json:"changes,omitempty"`
+	PullRequest       *PullRequest    `json:"pull_request"`
+	RequestedReviewer *User           `json:"requested_reviewer"`
+	Repository        *Repository     `json:"repository"`
+	Sender            *User           `json:"sender"`
+	CommitID          string          `json:"commit_id"`
+	Review            *ReviewPayload  `json:"review"`
 }
 
 // JSONPayload FIXME
diff --git a/modules/structs/pull.go b/modules/structs/pull.go
index f64bb83af9..a4a6f60b05 100644
--- a/modules/structs/pull.go
+++ b/modules/structs/pull.go
@@ -9,19 +9,20 @@ import (
 
 // PullRequest represents a pull request
 type PullRequest struct {
-	ID        int64      `json:"id"`
-	URL       string     `json:"url"`
-	Index     int64      `json:"number"`
-	Poster    *User      `json:"user"`
-	Title     string     `json:"title"`
-	Body      string     `json:"body"`
-	Labels    []*Label   `json:"labels"`
-	Milestone *Milestone `json:"milestone"`
-	Assignee  *User      `json:"assignee"`
-	Assignees []*User    `json:"assignees"`
-	State     StateType  `json:"state"`
-	IsLocked  bool       `json:"is_locked"`
-	Comments  int        `json:"comments"`
+	ID                 int64      `json:"id"`
+	URL                string     `json:"url"`
+	Index              int64      `json:"number"`
+	Poster             *User      `json:"user"`
+	Title              string     `json:"title"`
+	Body               string     `json:"body"`
+	Labels             []*Label   `json:"labels"`
+	Milestone          *Milestone `json:"milestone"`
+	Assignee           *User      `json:"assignee"`
+	Assignees          []*User    `json:"assignees"`
+	RequestedReviewers []*User    `json:"requested_reviewers"`
+	State              StateType  `json:"state"`
+	IsLocked           bool       `json:"is_locked"`
+	Comments           int        `json:"comments"`
 
 	HTMLURL  string `json:"html_url"`
 	DiffURL  string `json:"diff_url"`
diff --git a/modules/webhook/structs.go b/modules/webhook/structs.go
index 96012de352..927a91a74c 100644
--- a/modules/webhook/structs.go
+++ b/modules/webhook/structs.go
@@ -5,26 +5,27 @@ package webhook
 
 // HookEvents is a set of web hook events
 type HookEvents struct {
-	Create               bool `json:"create"`
-	Delete               bool `json:"delete"`
-	Fork                 bool `json:"fork"`
-	Issues               bool `json:"issues"`
-	IssueAssign          bool `json:"issue_assign"`
-	IssueLabel           bool `json:"issue_label"`
-	IssueMilestone       bool `json:"issue_milestone"`
-	IssueComment         bool `json:"issue_comment"`
-	Push                 bool `json:"push"`
-	PullRequest          bool `json:"pull_request"`
-	PullRequestAssign    bool `json:"pull_request_assign"`
-	PullRequestLabel     bool `json:"pull_request_label"`
-	PullRequestMilestone bool `json:"pull_request_milestone"`
-	PullRequestComment   bool `json:"pull_request_comment"`
-	PullRequestReview    bool `json:"pull_request_review"`
-	PullRequestSync      bool `json:"pull_request_sync"`
-	Wiki                 bool `json:"wiki"`
-	Repository           bool `json:"repository"`
-	Release              bool `json:"release"`
-	Package              bool `json:"package"`
+	Create                   bool `json:"create"`
+	Delete                   bool `json:"delete"`
+	Fork                     bool `json:"fork"`
+	Issues                   bool `json:"issues"`
+	IssueAssign              bool `json:"issue_assign"`
+	IssueLabel               bool `json:"issue_label"`
+	IssueMilestone           bool `json:"issue_milestone"`
+	IssueComment             bool `json:"issue_comment"`
+	Push                     bool `json:"push"`
+	PullRequest              bool `json:"pull_request"`
+	PullRequestAssign        bool `json:"pull_request_assign"`
+	PullRequestLabel         bool `json:"pull_request_label"`
+	PullRequestMilestone     bool `json:"pull_request_milestone"`
+	PullRequestComment       bool `json:"pull_request_comment"`
+	PullRequestReview        bool `json:"pull_request_review"`
+	PullRequestSync          bool `json:"pull_request_sync"`
+	PullRequestReviewRequest bool `json:"pull_request_review_request"`
+	Wiki                     bool `json:"wiki"`
+	Repository               bool `json:"repository"`
+	Release                  bool `json:"release"`
+	Package                  bool `json:"package"`
 }
 
 // HookEvent represents events that will delivery hook.
diff --git a/modules/webhook/type.go b/modules/webhook/type.go
index db4ab17931..7042d391b7 100644
--- a/modules/webhook/type.go
+++ b/modules/webhook/type.go
@@ -26,6 +26,7 @@ const (
 	HookEventPullRequestReviewRejected HookEventType = "pull_request_review_rejected"
 	HookEventPullRequestReviewComment  HookEventType = "pull_request_review_comment"
 	HookEventPullRequestSync           HookEventType = "pull_request_sync"
+	HookEventPullRequestReviewRequest  HookEventType = "pull_request_review_request"
 	HookEventWiki                      HookEventType = "wiki"
 	HookEventRepository                HookEventType = "repository"
 	HookEventRelease                   HookEventType = "release"
@@ -46,7 +47,7 @@ func (h HookEventType) Event() string {
 	case HookEventIssues, HookEventIssueAssign, HookEventIssueLabel, HookEventIssueMilestone:
 		return "issues"
 	case HookEventPullRequest, HookEventPullRequestAssign, HookEventPullRequestLabel, HookEventPullRequestMilestone,
-		HookEventPullRequestSync:
+		HookEventPullRequestSync, HookEventPullRequestReviewRequest:
 		return "pull_request"
 	case HookEventIssueComment, HookEventPullRequestComment:
 		return "issue_comment"
diff --git a/options/locale/locale_en-US.ini b/options/locale/locale_en-US.ini
index d863cc72bf..458c99f7fe 100644
--- a/options/locale/locale_en-US.ini
+++ b/options/locale/locale_en-US.ini
@@ -2118,6 +2118,8 @@ settings.event_pull_request_review = Pull Request Reviewed
 settings.event_pull_request_review_desc = Pull request approved, rejected, or review comment.
 settings.event_pull_request_sync = Pull Request Synchronized
 settings.event_pull_request_sync_desc = Pull request synchronized.
+settings.event_pull_request_review_request = Pull Request Review Requested
+settings.event_pull_request_review_request_desc = Pull request review requested or review request removed.
 settings.event_pull_request_approvals = Pull Request Approvals
 settings.event_pull_request_merge = Pull Request Merge
 settings.event_package = Package
diff --git a/routers/api/v1/utils/hook.go b/routers/api/v1/utils/hook.go
index 44625cc9b8..b62d20a18a 100644
--- a/routers/api/v1/utils/hook.go
+++ b/routers/api/v1/utils/hook.go
@@ -179,25 +179,26 @@ func addHook(ctx *context.APIContext, form *api.CreateHookOption, ownerID, repoI
 		HookEvent: &webhook_module.HookEvent{
 			ChooseEvents: true,
 			HookEvents: webhook_module.HookEvents{
-				Create:               util.SliceContainsString(form.Events, string(webhook_module.HookEventCreate), true),
-				Delete:               util.SliceContainsString(form.Events, string(webhook_module.HookEventDelete), true),
-				Fork:                 util.SliceContainsString(form.Events, string(webhook_module.HookEventFork), true),
-				Issues:               issuesHook(form.Events, "issues_only"),
-				IssueAssign:          issuesHook(form.Events, string(webhook_module.HookEventIssueAssign)),
-				IssueLabel:           issuesHook(form.Events, string(webhook_module.HookEventIssueLabel)),
-				IssueMilestone:       issuesHook(form.Events, string(webhook_module.HookEventIssueMilestone)),
-				IssueComment:         issuesHook(form.Events, string(webhook_module.HookEventIssueComment)),
-				Push:                 util.SliceContainsString(form.Events, string(webhook_module.HookEventPush), true),
-				PullRequest:          pullHook(form.Events, "pull_request_only"),
-				PullRequestAssign:    pullHook(form.Events, string(webhook_module.HookEventPullRequestAssign)),
-				PullRequestLabel:     pullHook(form.Events, string(webhook_module.HookEventPullRequestLabel)),
-				PullRequestMilestone: pullHook(form.Events, string(webhook_module.HookEventPullRequestMilestone)),
-				PullRequestComment:   pullHook(form.Events, string(webhook_module.HookEventPullRequestComment)),
-				PullRequestReview:    pullHook(form.Events, "pull_request_review"),
-				PullRequestSync:      pullHook(form.Events, string(webhook_module.HookEventPullRequestSync)),
-				Wiki:                 util.SliceContainsString(form.Events, string(webhook_module.HookEventWiki), true),
-				Repository:           util.SliceContainsString(form.Events, string(webhook_module.HookEventRepository), true),
-				Release:              util.SliceContainsString(form.Events, string(webhook_module.HookEventRelease), true),
+				Create:                   util.SliceContainsString(form.Events, string(webhook_module.HookEventCreate), true),
+				Delete:                   util.SliceContainsString(form.Events, string(webhook_module.HookEventDelete), true),
+				Fork:                     util.SliceContainsString(form.Events, string(webhook_module.HookEventFork), true),
+				Issues:                   issuesHook(form.Events, "issues_only"),
+				IssueAssign:              issuesHook(form.Events, string(webhook_module.HookEventIssueAssign)),
+				IssueLabel:               issuesHook(form.Events, string(webhook_module.HookEventIssueLabel)),
+				IssueMilestone:           issuesHook(form.Events, string(webhook_module.HookEventIssueMilestone)),
+				IssueComment:             issuesHook(form.Events, string(webhook_module.HookEventIssueComment)),
+				Push:                     util.SliceContainsString(form.Events, string(webhook_module.HookEventPush), true),
+				PullRequest:              pullHook(form.Events, "pull_request_only"),
+				PullRequestAssign:        pullHook(form.Events, string(webhook_module.HookEventPullRequestAssign)),
+				PullRequestLabel:         pullHook(form.Events, string(webhook_module.HookEventPullRequestLabel)),
+				PullRequestMilestone:     pullHook(form.Events, string(webhook_module.HookEventPullRequestMilestone)),
+				PullRequestComment:       pullHook(form.Events, string(webhook_module.HookEventPullRequestComment)),
+				PullRequestReview:        pullHook(form.Events, "pull_request_review"),
+				PullRequestReviewRequest: pullHook(form.Events, string(webhook_module.HookEventPullRequestReviewRequest)),
+				PullRequestSync:          pullHook(form.Events, string(webhook_module.HookEventPullRequestSync)),
+				Wiki:                     util.SliceContainsString(form.Events, string(webhook_module.HookEventWiki), true),
+				Repository:               util.SliceContainsString(form.Events, string(webhook_module.HookEventRepository), true),
+				Release:                  util.SliceContainsString(form.Events, string(webhook_module.HookEventRelease), true),
 			},
 			BranchFilter: form.BranchFilter,
 		},
@@ -379,6 +380,7 @@ func editHook(ctx *context.APIContext, form *api.EditHookOption, w *webhook.Webh
 	w.PullRequestMilestone = pullHook(form.Events, string(webhook_module.HookEventPullRequestMilestone))
 	w.PullRequestComment = pullHook(form.Events, string(webhook_module.HookEventPullRequestComment))
 	w.PullRequestReview = pullHook(form.Events, "pull_request_review")
+	w.PullRequestReviewRequest = pullHook(form.Events, string(webhook_module.HookEventPullRequestReviewRequest))
 	w.PullRequestSync = pullHook(form.Events, string(webhook_module.HookEventPullRequestSync))
 
 	if err := w.UpdateEvent(); err != nil {
diff --git a/routers/web/repo/issue.go b/routers/web/repo/issue.go
index d7ea3f12f1..1511716c1e 100644
--- a/routers/web/repo/issue.go
+++ b/routers/web/repo/issue.go
@@ -576,7 +576,7 @@ func RetrieveRepoReviewers(ctx *context.Context, repo *repo_model.Repository, is
 	}
 	ctx.Data["OriginalReviews"] = originalAuthorReviews
 
-	reviews, err := issues_model.GetReviewersByIssueID(issue.ID)
+	reviews, err := issues_model.GetReviewsByIssueID(issue.ID)
 	if err != nil {
 		ctx.ServerError("GetReviewersByIssueID", err)
 		return
diff --git a/routers/web/repo/webhook.go b/routers/web/repo/webhook.go
index 46b0f49108..5139c0b091 100644
--- a/routers/web/repo/webhook.go
+++ b/routers/web/repo/webhook.go
@@ -160,26 +160,27 @@ func ParseHookEvent(form forms.WebhookForm) *webhook_module.HookEvent {
 		SendEverything: form.SendEverything(),
 		ChooseEvents:   form.ChooseEvents(),
 		HookEvents: webhook_module.HookEvents{
-			Create:               form.Create,
-			Delete:               form.Delete,
-			Fork:                 form.Fork,
-			Issues:               form.Issues,
-			IssueAssign:          form.IssueAssign,
-			IssueLabel:           form.IssueLabel,
-			IssueMilestone:       form.IssueMilestone,
-			IssueComment:         form.IssueComment,
-			Release:              form.Release,
-			Push:                 form.Push,
-			PullRequest:          form.PullRequest,
-			PullRequestAssign:    form.PullRequestAssign,
-			PullRequestLabel:     form.PullRequestLabel,
-			PullRequestMilestone: form.PullRequestMilestone,
-			PullRequestComment:   form.PullRequestComment,
-			PullRequestReview:    form.PullRequestReview,
-			PullRequestSync:      form.PullRequestSync,
-			Wiki:                 form.Wiki,
-			Repository:           form.Repository,
-			Package:              form.Package,
+			Create:                   form.Create,
+			Delete:                   form.Delete,
+			Fork:                     form.Fork,
+			Issues:                   form.Issues,
+			IssueAssign:              form.IssueAssign,
+			IssueLabel:               form.IssueLabel,
+			IssueMilestone:           form.IssueMilestone,
+			IssueComment:             form.IssueComment,
+			Release:                  form.Release,
+			Push:                     form.Push,
+			PullRequest:              form.PullRequest,
+			PullRequestAssign:        form.PullRequestAssign,
+			PullRequestLabel:         form.PullRequestLabel,
+			PullRequestMilestone:     form.PullRequestMilestone,
+			PullRequestComment:       form.PullRequestComment,
+			PullRequestReview:        form.PullRequestReview,
+			PullRequestSync:          form.PullRequestSync,
+			PullRequestReviewRequest: form.PullRequestReviewRequest,
+			Wiki:                     form.Wiki,
+			Repository:               form.Repository,
+			Package:                  form.Package,
 		},
 		BranchFilter: form.BranchFilter,
 	}
diff --git a/services/convert/pull.go b/services/convert/pull.go
index 4989e82cd4..598187ca6e 100644
--- a/services/convert/pull.go
+++ b/services/convert/pull.go
@@ -88,6 +88,14 @@ func ToAPIPullRequest(ctx context.Context, pr *issues_model.PullRequest, doer *u
 		},
 	}
 
+	if err = pr.LoadRequestedReviewers(ctx); err != nil {
+		log.Error("LoadRequestedReviewers[%d]: %v", pr.ID, err)
+		return nil
+	}
+	for _, reviewer := range pr.RequestedReviewers {
+		apiPullRequest.RequestedReviewers = append(apiPullRequest.RequestedReviewers, ToUser(ctx, reviewer, nil))
+	}
+
 	if pr.Issue.ClosedUnix != 0 {
 		apiPullRequest.Closed = pr.Issue.ClosedUnix.AsTimePtr()
 	}
diff --git a/services/forms/repo_form.go b/services/forms/repo_form.go
index cacfb64b17..8108a55f7a 100644
--- a/services/forms/repo_form.go
+++ b/services/forms/repo_form.go
@@ -228,30 +228,31 @@ func (f *ProtectBranchForm) Validate(req *http.Request, errs binding.Errors) bin
 
 // WebhookForm form for changing web hook
 type WebhookForm struct {
-	Events               string
-	Create               bool
-	Delete               bool
-	Fork                 bool
-	Issues               bool
-	IssueAssign          bool
-	IssueLabel           bool
-	IssueMilestone       bool
-	IssueComment         bool
-	Release              bool
-	Push                 bool
-	PullRequest          bool
-	PullRequestAssign    bool
-	PullRequestLabel     bool
-	PullRequestMilestone bool
-	PullRequestComment   bool
-	PullRequestReview    bool
-	PullRequestSync      bool
-	Wiki                 bool
-	Repository           bool
-	Package              bool
-	Active               bool
-	BranchFilter         string `binding:"GlobPattern"`
-	AuthorizationHeader  string
+	Events                   string
+	Create                   bool
+	Delete                   bool
+	Fork                     bool
+	Issues                   bool
+	IssueAssign              bool
+	IssueLabel               bool
+	IssueMilestone           bool
+	IssueComment             bool
+	Release                  bool
+	Push                     bool
+	PullRequest              bool
+	PullRequestAssign        bool
+	PullRequestLabel         bool
+	PullRequestMilestone     bool
+	PullRequestComment       bool
+	PullRequestReview        bool
+	PullRequestSync          bool
+	PullRequestReviewRequest bool
+	Wiki                     bool
+	Repository               bool
+	Package                  bool
+	Active                   bool
+	BranchFilter             string `binding:"GlobPattern"`
+	AuthorizationHeader      string
 }
 
 // PushOnly if the hook will be triggered when push
diff --git a/services/webhook/notifier.go b/services/webhook/notifier.go
index 1f7cb8d988..bd25e20805 100644
--- a/services/webhook/notifier.go
+++ b/services/webhook/notifier.go
@@ -719,6 +719,34 @@ func (m *webhookNotifier) NotifyPullRequestReview(ctx context.Context, pr *issue
 	}
 }
 
+func (m *webhookNotifier) NotifyPullReviewRequest(ctx context.Context, doer *user_model.User, issue *issues_model.Issue, reviewer *user_model.User, isRequest bool, comment *issues_model.Comment) {
+	if !issue.IsPull {
+		log.Warn("NotifyPullReviewRequest: issue is not a pull request: %v", issue.ID)
+		return
+	}
+	mode, _ := access_model.AccessLevelUnit(ctx, doer, issue.Repo, unit.TypePullRequests)
+	if err := issue.LoadPullRequest(ctx); err != nil {
+		log.Error("LoadPullRequest failed: %v", err)
+		return
+	}
+	apiPullRequest := &api.PullRequestPayload{
+		Index:             issue.Index,
+		PullRequest:       convert.ToAPIPullRequest(ctx, issue.PullRequest, nil),
+		RequestedReviewer: convert.ToUser(ctx, reviewer, nil),
+		Repository:        convert.ToRepo(ctx, issue.Repo, mode),
+		Sender:            convert.ToUser(ctx, doer, nil),
+	}
+	if isRequest {
+		apiPullRequest.Action = api.HookIssueReviewRequested
+	} else {
+		apiPullRequest.Action = api.HookIssueReviewRequestRemoved
+	}
+	if err := PrepareWebhooks(ctx, EventSource{Repository: issue.Repo}, webhook_module.HookEventPullRequestReviewRequest, apiPullRequest); err != nil {
+		log.Error("PrepareWebhooks [review_requested: %v]: %v", isRequest, err)
+		return
+	}
+}
+
 func (m *webhookNotifier) NotifyCreateRef(ctx context.Context, pusher *user_model.User, repo *repo_model.Repository, refType, refFullName, refID string) {
 	apiPusher := convert.ToUser(ctx, pusher, nil)
 	apiRepo := convert.ToRepo(ctx, repo, perm.AccessModeNone)
diff --git a/services/webhook/payloader.go b/services/webhook/payloader.go
index 9eff25628b..d53e65fa5e 100644
--- a/services/webhook/payloader.go
+++ b/services/webhook/payloader.go
@@ -43,7 +43,7 @@ func convertPayloader(s PayloadConvertor, p api.Payloader, event webhook_module.
 	case webhook_module.HookEventPush:
 		return s.Push(p.(*api.PushPayload))
 	case webhook_module.HookEventPullRequest, webhook_module.HookEventPullRequestAssign, webhook_module.HookEventPullRequestLabel,
-		webhook_module.HookEventPullRequestMilestone, webhook_module.HookEventPullRequestSync:
+		webhook_module.HookEventPullRequestMilestone, webhook_module.HookEventPullRequestSync, webhook_module.HookEventPullRequestReviewRequest:
 		return s.PullRequest(p.(*api.PullRequestPayload))
 	case webhook_module.HookEventPullRequestReviewApproved, webhook_module.HookEventPullRequestReviewRejected, webhook_module.HookEventPullRequestReviewComment:
 		return s.Review(p.(*api.PullRequestPayload), event)
diff --git a/templates/repo/settings/webhook/settings.tmpl b/templates/repo/settings/webhook/settings.tmpl
index 57745c0401..8b03a3c959 100644
--- a/templates/repo/settings/webhook/settings.tmpl
+++ b/templates/repo/settings/webhook/settings.tmpl
@@ -238,6 +238,16 @@
 				</div>
 			</div>
 		</div>
+		<!-- Pull Request Review Request -->
+		<div class="seven wide column">
+			<div class="field">
+				<div class="ui checkbox">
+					<input name="pull_request_review_request" type="checkbox" tabindex="0" {{if .Webhook.PullRequestReviewRequest}}checked{{end}}>
+					<label>{{.locale.Tr "repo.settings.event_pull_request_review_request"}}</label>
+					<span class="help">{{.locale.Tr "repo.settings.event_pull_request_review_request_desc"}}</span>
+				</div>
+			</div>
+		</div>
 	</div>
 </div>
 
diff --git a/templates/swagger/v1_json.tmpl b/templates/swagger/v1_json.tmpl
index 15402ecdfd..03a65184c3 100644
--- a/templates/swagger/v1_json.tmpl
+++ b/templates/swagger/v1_json.tmpl
@@ -19934,6 +19934,13 @@
           "type": "string",
           "x-go-name": "PatchURL"
         },
+        "requested_reviewers": {
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/User"
+          },
+          "x-go-name": "RequestedReviewers"
+        },
         "state": {
           "$ref": "#/definitions/StateType"
         },