Convert Excel file data to JSON string without any struct definition in Go

I am new to Go language. I have got a requirement where the application will read an Excel file and convert it to JSON string, without relying upon any defined struct. I have explored some libraries where either this struct definition is required or at least the Excel column headers have to be there. For example,

github.com/xuri/excelize
github.com/onkarvhanumante/Excel2JsonTree
github.com/FerdinaKusumah/excel2json

However, I am not able to find any such where it can just process the raw Excel data and convert it to a JSON.

Please guide me, thank you!

If it is okay to expect all values as String then you can do it as shown in the snippet below. The script reads all sheets(tabs) and creates JSON files in two formats, with and without headers.

package main

import (
	"encoding/json"
	"fmt"
	"os"

	"github.com/xuri/excelize/v2"
)

func main() {
	f, err := excelize.OpenFile("test.xlsx")
	if err != nil {
		fmt.Println(err)
		return
	}
	defer func() {
		if err := f.Close(); err != nil {
			fmt.Println(err)
		}
	}()

	// could have multiple sheets
	sheets := f.GetSheetList()
	for _, sheetName := range sheets {
		d, err := f.GetRows(sheetName)
		if err != nil {
			fmt.Println("error reading sheet", sheetName, ":", err)
			return
		}

		saveAsJSON(d, sheetName+".json")
		saveAsJSONWithHeaders(d, sheetName+"_with_headers.json")
	}

}

func saveAsJSONWithHeaders(rows [][]string, filename string) error {
	data := make([]map[string]string, len(rows)-1)
	headers := rows[0]
    // excluding header row
	for i, row := range rows[1:] {
		data[i] = make(map[string]string)
		for j, cellValue := range row {
			data[i][headers[j]] = cellValue
		}
	}

	return saveAsJSON(data, filename)
}

func saveAsJSON(data interface{}, filename string) error {
	file, err := os.Create(filename)
	if err != nil {
		return err
	}
	defer file.Close()
	encoder := json.NewEncoder(file)
	if err := encoder.Encode(data); err != nil {
		return err
	}
	return nil
}