SwitchInlineQueryCurrentChat with empty string doesn't get parsed

[trust-me-im-an-engineer]

Telegram bot api doc states that switch_inline_query_current_chat parameter in InlineKeyboardButton method "May be empty, in which case just the bot's username will be inserted". However trying to send button with empty parameter like this

models.InlineKeyboardButton{
	Text:                         "This button should insert bot's username with no additional text",
	SwitchInlineQueryCurrentChat: "",
}

fails with "bad request, Bad Request: BUTTON_COPY_TEXT_INVALID" error.

Same Button with single space SwitchInlineQueryCurrentChat: " " works. But this way bot inserts name, default space and additional space we sent. So inlie query has two spaces instead of one and therefore doesn't display placeholder message .

I believe that happens because of SwitchInlineQueryCurrentChat being string and not *string so there's no way for parser to different between unsed zero-valued field and field manually set to be empty.

[trust-me-im-an-engineer]

I've peeked into InlineKeyboardButton struct definition and found that SwitchInlineQueryCurrentChat field has omitempty json tag, but CopyTextButton field contains Text field without omitempty json tag. So having SwitchInlineQueryCurrentChat: "" leaves field empty in eyes of json marshaler and InlineKeyboardButton's optional fieds default to CopyText button with empty string.

I believe I can get around it by manually creating json for that specific request. Will update on my attempt.

[trust-me-im-an-engineer]

Got around it by utilizing the fact that ReplyMarkup type is any.

I used this types to replace InlineKeyboardMarkup and InlineKeyboardButton:

// inlineKeyboardMarkupAny is like models.InlineKeyboardMarkup but allows any InlineKeyboard type
type inlineKeyboardMarkupAny struct {
	InlineKeyboard [][]any `json:"inline_keyboard"`
}

// inlineKeyboardButtonSwitchInlineQueryCurrentChat is simplified botmodel.InlineKeyboardButton.
// It allows SwitchInlineQueryCurrentChat with empty string
type inlineKeyboardButtonSwitchInlineQueryCurrentChat struct {
	Text                         string `json:"text"`
	SwitchInlineQueryCurrentChat string `json:"switch_inline_query_current_chat"` // Notice that "omitempty" tag is removed
}

So ReplyMarkup for SendMessageParams looks like this:

ReplyMarkup: inlineKeyboardMarkupAny{
	InlineKeyboard: [][]any{
		{
			inlineKeyboardButtonSwitchInlineQueryCurrentChat{
				Text:                         "This button does insert bot's username with no additional text!",
				SwitchInlineQueryCurrentChat: "", // empty string doesn't result in error anymore!
			},
		},
		{
			botmodels.InlineKeyboardButton{
				Text:         "Normal InlineKeyboardButton button",
				CallbackData: "some_callback_data",
			},
		},
	},
}

This way SwitchInlineQueryCurrentChat can paste just bot's name and single space to current chat's input field and therefore placeholder message is displayed.