add ability to respond to inline queries with stickers

(cherry picked from commit 87891c10fe)

helpers.go

@@ -578,6 +578,16 @@ func NewInlineQueryResultCachedVideo(id, videoID, title string) InlineQueryResul
 	}
 }
 
+// NewInlineQueryResultCachedSticker create a new inline query with cached sticker.
+func NewInlineQueryResultCachedSticker(id, stickerID, title string) InlineQueryResultCachedSticker {
+	return InlineQueryResultCachedSticker{
+		Type:      "sticker",
+		ID:        id,
+		StickerID: stickerID,
+		Title:     title,
+	}
+}
+
 // NewInlineQueryResultAudio creates a new inline query audio.
 func NewInlineQueryResultAudio(id, url, title string) InlineQueryResultAudio {
 	return InlineQueryResultAudio{

types.go

@@ -834,6 +834,17 @@ type InlineQueryResultCachedVideo struct {
 	InputMessageContent interface{}           `json:"input_message_content,omitempty"`
 }
 
+// InlineQueryResultCachedSticker is an inline query response with cached sticker.
+type InlineQueryResultCachedSticker struct {
+	Type                string                `json:"type"`            // required
+	ID                  string                `json:"id"`              // required
+	StickerID           string                `json:"sticker_file_id"` // required
+	Title               string                `json:"title"`           // required
+	ParseMode           string                `json:"parse_mode"`
+	ReplyMarkup         *InlineKeyboardMarkup `json:"reply_markup,omitempty"`
+	InputMessageContent interface{}           `json:"input_message_content,omitempty"`
+}
+
 // InlineQueryResultAudio is an inline query response audio.
 type InlineQueryResultAudio struct {
 	Type                string                `json:"type"`      // required