APIv4 POST /reactions (#6092)

* APIv4 POST /reactions

* update corresponding V3 endpoint

model/client4.go

@@ -238,6 +238,10 @@ func (c *Client4) GetEmojiRoute(emojiId string) string {
 	return fmt.Sprintf(c.GetEmojisRoute()+"/%v", emojiId)
 }
 
+func (c *Client4) GetReactionsRoute() string {
+	return fmt.Sprintf("/reactions")
+}
+
 func (c *Client4) DoApiGet(url string, etag string) (*http.Response, *AppError) {
 	return c.DoApiRequest(http.MethodGet, url, "", etag)
 }
@@ -2374,6 +2378,16 @@ func (c *Client4) GetEmoji(emojiId string) (*Emoji, *Response) {
 
 // Reaction Section
 
+// SaveReaction saves an emoji reaction for a post. Returns the saved reaction if successful, otherwise an error will be returned.
+func (c *Client4) SaveReaction(reaction *Reaction) (*Reaction, *Response) {
+	if r, err := c.DoApiPost(c.GetReactionsRoute(), reaction.ToJson()); err != nil {
+		return nil, &Response{StatusCode: r.StatusCode, Error: err}
+	} else {
+		defer closeBody(r)
+		return ReactionFromJson(r.Body), BuildResponse(r)
+	}
+}
+
 // GetReactions returns a list of reactions to a post.
 func (c *Client4) GetReactions(postId string) ([]*Reaction, *Response) {
 	if r, err := c.DoApiGet(c.GetPostRoute(postId)+"/reactions", ""); err != nil {