How to save the variable into the last row of existed CSV file

Question

If I have some data to store into last row of a CSV file, how should I do it with Go? I do not know how to insert new data. I searched on google but no result at all.

Answer 1

If you want simply append some data to your csv file, you can open the file with flag and perm and write new things on the file.

Here is a sample code:

package main

import (
    "encoding/csv"
    "log"
    "os"
)

func main() {
    path := "sample.csv"
    file, err := os.OpenFile(path, os.O_APPEND|os.O_WRONLY, os.ModeAppend)
    if err != nil {
        log.Fatal(err)
    }
    defer file.Close()

    var data [][]string
    data = append(data, []string{"nice", "good"})
    data = append(data, []string{"good", "better"})

    w := csv.NewWriter(file)
    w.WriteAll(data)
}

Answer 2

This has been answered here:

Append to a file in Go

I have flagged this question as a duplicate.

I like the example given in the go docs here:

package main

import (
    "log"
    "os"
)

func main() {
    // If the file doesn't exist, create it, or append to the file
    f, err := os.OpenFile("access.log", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
    if err != nil {
        log.Fatal(err)
    }
    if _, err := f.Write([]byte("appended some data\n")); err != nil {
        log.Fatal(err)
    }
    if err := f.Close(); err != nil {
        log.Fatal(err)
    }
}

The flag os.O_APPEND is the important part which will add the new line to the end of the file.

Hope that helps.