APIv4 DELETE /users/{user_id}/posts/{post_id}/reactions/name (#6117)

* APIv4 DELETE /users/{user_id}/posts/{post_id}/reactions/name

* updated v3 deleteReaction endpoint

* update parameter of app.DeleteReactionForPost()

* update utils.IsValidAlphaNum, add utils.IsValidAlphaNumHyphenUnderscore, and add related tests

api4/context.go

@@ -468,7 +468,7 @@ func (c *Context) RequireCategory() *Context {
 		return c
 	}
 
-	if !model.IsValidAlphaNum(c.Params.Category, true) {
+	if !model.IsValidAlphaNumHyphenUnderscore(c.Params.Category, true) {
 		c.SetInvalidUrlParam("category")
 	}
 
@@ -492,13 +492,25 @@ func (c *Context) RequirePreferenceName() *Context {
 		return c
 	}
 
-	if !model.IsValidAlphaNum(c.Params.PreferenceName, true) {
+	if !model.IsValidAlphaNumHyphenUnderscore(c.Params.PreferenceName, true) {
 		c.SetInvalidUrlParam("preference_name")
 	}
 
 	return c
 }
 
+func (c *Context) RequireEmojiName() *Context {
+	if c.Err != nil {
+		return c
+	}
+
+	if len(c.Params.EmojiName) == 0 || len(c.Params.EmojiName) > 64 || !model.IsValidAlphaNumHyphenUnderscore(c.Params.EmojiName, false) {
+		c.SetInvalidUrlParam("emoji_name")
+	}
+
+	return c
+}
+
 func (c *Context) RequireHookId() *Context {
 	if c.Err != nil {
 		return c