PLT-2978: Add channel purpose change system message. (#5094)

Completes original patch by David Lu.

api/channel.go

@@ -262,6 +262,7 @@ func updateChannelHeader(c *Context, w http.ResponseWriter, r *http.Request) {
 }
 
 func updateChannelPurpose(c *Context, w http.ResponseWriter, r *http.Request) {
+
 	props := model.MapFromJson(r.Body)
 	channelId := props["channel_id"]
 	if len(channelId) != 26 {
@@ -292,6 +293,7 @@ func updateChannelPurpose(c *Context, w http.ResponseWriter, r *http.Request) {
 			return
 		}
 
+		oldChannelPurpose := channel.Purpose
 		channel.Purpose = channelPurpose
 
 		app.InvalidateCacheForChannel(channel.Id)
@@ -299,6 +301,9 @@ func updateChannelPurpose(c *Context, w http.ResponseWriter, r *http.Request) {
 			c.Err = ucresult.Err
 			return
 		} else {
+			if err := app.PostUpdateChannelPurposeMessage(c.Session.UserId, channel.Id, c.TeamId, oldChannelPurpose, channelPurpose); err != nil {
+				l4g.Error(err.Error())
+			}
 			c.LogAudit("name=" + channel.Name)
 			w.Write([]byte(channel.ToJson()))
 		}

api/channel_test.go

@@ -630,6 +630,17 @@ func TestUpdateChannelPurpose(t *testing.T) {
 		upChannel1 = result.Data.(*model.Channel)
 	}
 
+	time.Sleep(100 * time.Millisecond)
+
+	r1 := Client.Must(Client.GetPosts(channel1.Id, 0, 1, "")).Data.(*model.PostList)
+	if len(r1.Order) != 1 {
+		t.Fatal("Purpose update system message was not found")
+	} else if val, ok := r1.Posts[r1.Order[0]].Props["old_purpose"]; !ok || val != "" {
+		t.Fatal("Props should contain old_header with old purpose value")
+	} else if val, ok := r1.Posts[r1.Order[0]].Props["new_purpose"]; !ok || val != "new purpose" {
+		t.Fatal("Props should contain new_header with new purpose value")
+	}
+
 	if upChannel1.Purpose != data["channel_purpose"] {
 		t.Fatal("Failed to update purpose")
 	}

app/channel.go

@@ -316,6 +316,41 @@ func PostUpdateChannelHeaderMessage(userId string, channelId string, teamId stri
 	return nil
 }
 
+func PostUpdateChannelPurposeMessage(userId string, channelId string, teamId string, oldChannelPurpose string, newChannelPurpose string) *model.AppError {
+	uc := Srv.Store.User().Get(userId)
+
+	if uresult := <-uc; uresult.Err != nil {
+		return model.NewLocAppError("PostUpdateChannelPurposeMessage", "app.channel.post_update_channel_purpose_message.retrieve_user.error", nil, uresult.Err.Error())
+	} else {
+		user := uresult.Data.(*model.User)
+
+		var message string
+		if oldChannelPurpose == "" {
+			message = fmt.Sprintf(utils.T("app.channel.post_update_channel_purpose_message.updated_to"), user.Username, newChannelPurpose)
+		} else if newChannelPurpose == "" {
+			message = fmt.Sprintf(utils.T("app.channel.post_update_channel_purpose_message.removed"), user.Username, oldChannelPurpose)
+		} else {
+			message = fmt.Sprintf(utils.T("app.channel.post_update_channel_purpose_message.updated_from"), user.Username, oldChannelPurpose, newChannelPurpose)
+		}
+
+		post := &model.Post{
+			ChannelId: channelId,
+			Message:   message,
+			Type:      model.POST_PURPOSE_CHANGE,
+			UserId:    userId,
+			Props: model.StringInterface{
+				"old_purpose": oldChannelPurpose,
+				"new_purpose": newChannelPurpose,
+			},
+		}
+		if _, err := CreatePost(post, teamId, false); err != nil {
+			return model.NewLocAppError("", "app.channel.post_update_channel_purpose_message.post.error", nil, err.Error())
+		}
+	}
+
+	return nil
+}
+
 func PostUpdateChannelDisplayNameMessage(userId string, channelId string, teamId string, oldChannelDisplayName, newChannelDisplayName string) *model.AppError {
 	uc := Srv.Store.User().Get(userId)
 

i18n/en.json

@@ -331,6 +331,26 @@
     "id": "api.channel.post_update_channel_header_message_and_forget.updated_to",
     "translation": "%s updated the channel header to: %s"
   },
+  {
+    "id": "app.channel.post_update_channel_purpose_message.post.error",
+    "translation": "Failed to post channel purpose message"
+  },
+  {
+    "id": "app.channel.post_update_channel_purpose_message.removed",
+    "translation": "%s removed the channel purpose (was: %s)"
+  },
+  {
+    "id": "app.channel.post_update_channel_purpose_message.retrieve_user.error",
+    "translation": "Failed to retrieve user while trying to save update channel purpose message %v"
+  },
+  {
+    "id": "app.channel.post_update_channel_purpose_message.updated_from",
+    "translation": "%s updated the channel purpose from: %s to: %s"
+  },
+  {
+    "id": "app.channel.post_update_channel_purpose_message.updated_to",
+    "translation": "%s updated the channel purpose to: %s"
+  },
   {
     "id": "api.channel.post_user_add_remove_message_and_forget.error",
     "translation": "Failed to post join/leave message"

model/post.go

@@ -18,6 +18,7 @@ const (
 	POST_ADD_REMOVE            = "system_add_remove"
 	POST_HEADER_CHANGE         = "system_header_change"
 	POST_DISPLAYNAME_CHANGE    = "system_displayname_change"
+	POST_PURPOSE_CHANGE        = "system_purpose_change"
 	POST_CHANNEL_DELETED       = "system_channel_deleted"
 	POST_EPHEMERAL             = "system_ephemeral"
 	POST_FILEIDS_MAX_RUNES     = 150
@@ -120,7 +121,7 @@ func (o *Post) IsValid() *AppError {
 
 	// should be removed once more message types are supported
 	if !(o.Type == POST_DEFAULT || o.Type == POST_JOIN_LEAVE || o.Type == POST_ADD_REMOVE ||
-		o.Type == POST_SLACK_ATTACHMENT || o.Type == POST_HEADER_CHANGE ||
+		o.Type == POST_SLACK_ATTACHMENT || o.Type == POST_HEADER_CHANGE || o.Type == POST_PURPOSE_CHANGE ||
 		o.Type == POST_DISPLAYNAME_CHANGE || o.Type == POST_CHANNEL_DELETED) {
 		return NewLocAppError("Post.IsValid", "model.post.is_valid.type.app_error", nil, "id="+o.Type)
 	}

webapp/components/edit_channel_purpose_modal.jsx

@@ -2,7 +2,7 @@
 // See License.txt for license information.
 
 import PreferenceStore from 'stores/preference_store.jsx';
-
+import AppDispatcher from '../dispatcher/app_dispatcher.jsx';
 import * as AsyncClient from 'utils/async_client.jsx';
 import Client from 'client/web_client.jsx';
 import Constants from 'utils/constants.jsx';
@@ -67,10 +67,15 @@ export default class EditChannelPurposeModal extends React.Component {
         Client.updateChannelPurpose(
             this.props.channel.id,
             this.refs.purpose.value.trim(),
-            () => {
+            (channel) => {
                 AsyncClient.getChannel(this.props.channel.id);
 
                 this.handleHide();
+
+                AppDispatcher.handleServerAction({
+                    type: Constants.ActionTypes.RECEIVED_CHANNEL,
+                    channel
+                });
             },
             (err) => {
                 if (err.id === 'api.context.invalid_param.app_error') {