PLT-7404 Return viewed at times in view channel API response (#7428)

* Return viewed at times in view channel API response

* Updated transaction to read and write once

* Remove transaction and only update if new value greater than older

3 files changed, 66 insertions, 3 deletions

diff --git a/model/channel_view.go b/model/channel_view.go
index 8a7ead76f..e7b1de306 100644
--- a/model/channel_view.go
+++ b/model/channel_view.go
@@ -32,3 +32,28 @@ func ChannelViewFromJson(data io.Reader) *ChannelView {
 		return nil
 	}
 }
+
+type ChannelViewResponse struct {
+	Status            string           `json:"status"`
+	LastViewedAtTimes map[string]int64 `json:"last_viewed_at_times"`
+}
+
+func (o *ChannelViewResponse) ToJson() string {
+	b, err := json.Marshal(o)
+	if err != nil {
+		return ""
+	} else {
+		return string(b)
+	}
+}
+
+func ChannelViewResponseFromJson(data io.Reader) *ChannelViewResponse {
+	decoder := json.NewDecoder(data)
+	var o ChannelViewResponse
+	err := decoder.Decode(&o)
+	if err == nil {
+		return &o
+	} else {
+		return nil
+	}
+}
diff --git a/model/channel_view_test.go b/model/channel_view_test.go
new file mode 100644
index 000000000..fac455a74
--- /dev/null
+++ b/model/channel_view_test.go
@@ -0,0 +1,38 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package model
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestChannelViewJson(t *testing.T) {
+	o := ChannelView{ChannelId: NewId(), PrevChannelId: NewId()}
+	json := o.ToJson()
+	ro := ChannelViewFromJson(strings.NewReader(json))
+
+	if o.ChannelId != ro.ChannelId {
+		t.Fatal("ChannelIdIds do not match")
+	}
+
+	if o.PrevChannelId != ro.PrevChannelId {
+		t.Fatal("PrevChannelIds do not match")
+	}
+}
+
+func TestChannelViewResponseJson(t *testing.T) {
+	id := NewId()
+	o := ChannelViewResponse{Status: "OK", LastViewedAtTimes: map[string]int64{id: 12345}}
+	json := o.ToJson()
+	ro := ChannelViewResponseFromJson(strings.NewReader(json))
+
+	if o.Status != ro.Status {
+		t.Fatal("ChannelIdIds do not match")
+	}
+
+	if o.LastViewedAtTimes[id] != ro.LastViewedAtTimes[id] {
+		t.Fatal("LastViewedAtTimes do not match")
+	}
+}
diff --git a/model/client4.go b/model/client4.go
index 42e89fd9c..eb8568a5e 100644
--- a/model/client4.go
+++ b/model/client4.go
@@ -1570,13 +1570,13 @@ func (c *Client4) GetChannelMembersForUser(userId, teamId, etag string) (*Channe
 }
 
 // ViewChannel performs a view action for a user. Synonymous with switching channels or marking channels as read by a user.
-func (c *Client4) ViewChannel(userId string, view *ChannelView) (bool, *Response) {
+func (c *Client4) ViewChannel(userId string, view *ChannelView) (*ChannelViewResponse, *Response) {
 	url := fmt.Sprintf(c.GetChannelsRoute()+"/members/%v/view", userId)
 	if r, err := c.DoApiPost(url, view.ToJson()); err != nil {
-		return false, BuildErrorResponse(r, err)
+		return nil, BuildErrorResponse(r, err)
 	} else {
 		defer closeBody(r)
-		return CheckStatusOK(r), BuildResponse(r)
+		return ChannelViewResponseFromJson(r.Body), BuildResponse(r)
 	}
 }