I want to make a chatbot by using GEMINI API for a fund advisor in flutter but i want to make Gemini read that xlsx file and respond me by reading that. But I failed always. There are instances at python or javascript but i cant find it for flutter

void _sendMessage() async {
    try {
      final messageText = _controller.text.trim();
      if (messageText.isEmpty) return;
      _controller.clear();
      setState(() {
        _messages.add(Message(text: messageText, isUser: true));
        _isLoading = true; // Set loading state when sending message
      });
      _scrollToBottom();
      final model = GenerativeModel(
          model: 'gemini-pro',
          apiKey: 'API-KEY');
      final content = [Content.text(messageText)];
      final response = await model.generateContent(content);

      setState(() {
        _messages.add(Message(text: response.text!, isUser: false));
        _isLoading = false; // Clear loading state after receiving response
      });
      _scrollToBottom();
      _controller.clear();
    } catch (e) {
      log("Error : $e");
      setState(() {
        _isLoading = false; // Ensure loading state is cleared on error
      });
    }
  }

thats my message code im sending gemini messages and getting responds from here and I tried file reading by that code

 final geminiApi = GeminiApi('API-KEY');
      const filePath = 'assets/data.xlsx';
      const mimeType = 'application/vnd.google-apps.spreadsheet';

      // Upload the file
      final fileResponse = await geminiApi.uploadFile(filePath, mimeType);
      final fileId = fileResponse['id'];

      // Wait for the file to be processed
      await geminiApi.waitForFileProcessing(fileId);

thats for i tried make it read from that code but it didnt work