MM-16499: Adds ability to retrieve channels with total count f… (#11375)

* MM-16499: Adds ability to retrieve channels with total count for pagination.

* MM-16499: Switches to custom package name for squirrel.

api4/channel.go

@@ -534,7 +534,23 @@ func getAllChannels(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	w.Write([]byte(channels.ToJson()))
+	var payload []byte
+	if c.Params.IncludeTotalCount {
+		totalCount, err := c.App.GetAllChannelsCount(opts)
+		if err != nil {
+			c.Err = err
+			return
+		}
+		cwc := &model.ChannelsWithCount{
+			Channels:   channels,
+			TotalCount: totalCount,
+		}
+		payload = cwc.ToJson()
+	} else {
+		payload = []byte(channels.ToJson())
+	}
+
+	w.Write(payload)
 }
 
 func getPublicChannelsForTeam(c *Context, w http.ResponseWriter, r *http.Request) {

api4/channel_test.go

@@ -832,6 +832,37 @@ func TestGetAllChannels(t *testing.T) {
 	CheckForbiddenStatus(t, resp)
 }
 
+func TestGetAllChannelsWithCount(t *testing.T) {
+	th := Setup().InitBasic()
+	defer th.TearDown()
+	Client := th.Client
+
+	channels, total, resp := th.SystemAdminClient.GetAllChannelsWithCount(0, 20, "")
+	CheckNoError(t, resp)
+
+	// At least, all the not-deleted channels created during the InitBasic
+	require.True(t, len(*channels) >= 3)
+	for _, c := range *channels {
+		require.NotEqual(t, c.TeamId, "")
+	}
+	require.Equal(t, int64(5), total)
+
+	channels, _, resp = th.SystemAdminClient.GetAllChannelsWithCount(0, 10, "")
+	CheckNoError(t, resp)
+	require.True(t, len(*channels) >= 3)
+
+	channels, _, resp = th.SystemAdminClient.GetAllChannelsWithCount(1, 1, "")
+	CheckNoError(t, resp)
+	require.Len(t, *channels, 1)
+
+	channels, _, resp = th.SystemAdminClient.GetAllChannelsWithCount(10000, 10000, "")
+	CheckNoError(t, resp)
+	require.Len(t, *channels, 0)
+
+	_, _, resp = Client.GetAllChannelsWithCount(0, 20, "")
+	CheckForbiddenStatus(t, resp)
+}
+
 func TestSearchChannels(t *testing.T) {
 	th := Setup().InitBasic()
 	defer th.TearDown()