Dumping MySQL tables to JSON with Golang

Question

Was putting together a quick dumper for MySQL to JSON in Go. However I find that everything that I retrieve from the database is a []byte array. Thus instead of n

Answer 1

Based on the answers here, this is the most efficient code I could come up with. Note that this is outputting each row as a separate JSON array to save key name repetition.

// OutputJSONMysqlRowsStream outputs rows as a JSON array stream to save ram & output size due to key name repetition
func OutputJSONMysqlRowsStream(writer http.ResponseWriter, rows *sql.Rows) {

    defer rows.Close()

    columns, err := rows.Columns()

    if err != nil {
        OutputJSONError(writer, "Failed to get column names")
        return
    }

    jsonColumns, err := json.Marshal(columns)

    if err != nil {
        OutputJSONError(writer, "Failed to encode json of column names")
        return
    }

    writer.Header().Set("Content-Type", "application/cal-json-stream; charset=utf-8")

    fmt.Fprintln(writer, "{\"status\": \"done\", \"data\":{ \"json_stream_fields\":"+string(jsonColumns)+"}}")

    columnCount := len(columns)
    rowDataHolder := make([]interface{}, columnCount)
    rowDataHolderPointers := make([]interface{}, columnCount)

    if err != nil {
        log.Println(err)
    }

    for rows.Next() {

        for i := 0; i < columnCount; i++ {
            rowDataHolderPointers[i] = &rowDataHolder[i]
        }

        err := rows.Scan(rowDataHolderPointers...)

        if err != nil {
            log.Println(err)
        } else {

            for i, value := range rowDataHolder {
                tempValue, ok := value.([]byte)

                if ok {
                    rowDataHolder[i] = string(tempValue)
                }
            }

            jsonEncoder := json.NewEncoder(writer)
            err = jsonEncoder.Encode(rowDataHolder)

            if err != nil {
                log.Println(err)
            }
        }
    }
}