csv Read

numbers.csv

1,2,3,4,5
6,7,8,9,10

code sample:

package main

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

func main() {

    f, err := os.Open("numbers.csv")

    if err != nil {

        log.Fatal(err)
    }

    r := csv.NewReader(f)

    for {

        record, err := r.Read()

        if err == io.EOF {
            break
        }

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

        for value := range record {
            fmt.Printf("%s\n", record[value])
        }
    }
}

CSV ReadAll

users.csv

first_name,last_name,occupation
John,Doe,gardener
Lucy,Smith,teacher
Brian,Bethamy,programmer

package main

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

type User struct {
    firstName  string
    lastName   string
    occupation string
}

func main() {

    records, err := readData("users.csv")

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

    for _, record := range records {

        user := User{
            firstName:  record[0],
            lastName:   record[1],
            occupation: record[2],
        }

        fmt.Printf("%s %s is a %s\n", user.firstName, user.lastName,
            user.occupation)
    }
}

func readData(fileName string) ([][]string, error) {

    f, err := os.Open(fileName)

    if err != nil {
        return [][]string{}, err
    }

    defer f.Close()

    r := csv.NewReader(f)

    // skip first line
    if _, err := r.Read(); err != nil {
        return [][]string{}, err
    }

    records, err := r.ReadAll()

    if err != nil {
        return [][]string{}, err
    }

    return records, nil
}

CSV different delimiter

users.csv

# this is users.csv file

John;Doe;gardener
Lucy;Smith;teacher
Brian;Bethamy;programmer

package main

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

func main() {

    f, err := os.Open("users.csv")

    if err != nil {

        log.Fatal(err)
    }

    r := csv.NewReader(f)
    r.Comma = ';'
    r.Comment = '#'

    records, err := r.ReadAll()

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

    fmt.Print(records)
}

r := csv.NewReader(f)
r.Comma = ';'
r.Comment = '#'

CSV Write

package main

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

func main() {

    records := [][]string{
        {"first_name", "last_name", "occupation"},
        {"John", "Doe", "gardener"},
        {"Lucy", "Smith", "teacher"},
        {"Brian", "Bethamy", "programmer"},
    }

    f, err := os.Create("users.csv")
    defer f.Close()

    if err != nil {

        log.Fatalln("failed to open file", err)
    }

    w := csv.NewWriter(f)
    defer w.Flush()

    for _, record := range records {
        if err := w.Write(record); err != nil {
            log.Fatalln("error writing record to file", err)
        }
    }
}

CSV WriteAll

package main

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

func main() {

    records := [][]string{
        {"first_name", "last_name", "occupation"},
        {"John", "Doe", "gardener"},
        {"Lucy", "Smith", "teacher"},
        {"Brian", "Bethamy", "programmer"},
    }

    f, err := os.Create("users.csv")
    defer f.Close()

    if err != nil {

        log.Fatalln("failed to open file", err)
    }

    w := csv.NewWriter(f)
    err = w.WriteAll(records) // calls Flush internally

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

https://zetcode.com/golang/csv/