[PLT-7362] Option to add user to channel if mentioned user is not currently in the channel (#7619)

* Option to add user to channel if mentioned user is not currently in the channel

* instead of link from server, just add component on client side to add channel member

* change implementation using post.props

* do clean up and add test

* sanitize post.props['add_channel_member'] on post creation

* move sanitize to app.CreatePost and also apply to app.UpdatePost

1 files changed, 13 insertions, 0 deletions

diff --git a/model/post.go b/model/post.go
index 523a97c73..a5ae0b82a 100644
--- a/model/post.go
+++ b/model/post.go
@@ -33,6 +33,7 @@ const (
 	POST_MESSAGE_MAX_RUNES     = 4000
 	POST_PROPS_MAX_RUNES       = 8000
 	POST_CUSTOM_TYPE_PREFIX    = "custom_"
+	PROPS_ADD_CHANNEL_MEMBER   = "add_channel_member"
 )
 
 type Post struct {
@@ -188,6 +189,18 @@ func (o *Post) IsValid() *AppError {
 	return nil
 }
 
+func (o *Post) SanitizeProps() {
+	membersToSanitize := []string{
+		PROPS_ADD_CHANNEL_MEMBER,
+	}
+
+	for _, member := range membersToSanitize {
+		if _, ok := o.Props[member]; ok {
+			delete(o.Props, member)
+		}
+	}
+}
+
 func (o *Post) PreSave() {
 	if o.Id == "" {
 		o.Id = NewId()