golang convert a struct to a byte array

[Juan Torres]

I´m try to convert a struct to a byte array, but i´m getting a error and i´m no sure it´s the best way,

can help me?

package main

import (

    "bytes"

    "encoding/binary"

    "fmt"

)

//My Struct

type Number struct {

    One       string

    Two     string

}

func main() {

buf := new(bytes.Buffer)

var number Number

key := "1"

number.One = key

number.Two = "2"

err := binary.Write(buf, binary.BigEndian, &number)

if err != nil {

fmt.Println("binary.Write failed:", err)

}

}

Error result :     binary.Write failed: binary.Write: invalid type string

[Jan Mercl]

On Mon, Mar 31, 2014 at 5:11 PM, Juan Torres <juantor...@gmail.com> wrote:

""""
Data must be a fixed-size value or a slice of fixed-size values, or a
pointer to such data.
""""[0]


"1" or "foo" or "whatever" is not a fixed size value.

[0]: http://golang.org/pkg/encoding/binary/#Write

-j

[Gyepi SAM]

On Mon, Mar 31, 2014 at 08:11:37AM -0700, Juan Torres wrote:
> I´m try to convert a struct to a byte array, but i´m getting a error and
> i´m no sure it´s the best way,
> can help me?

encoding/binary doesn't encode structs.
encoding/gob and encoding/json do, among others.

However, I should ask, what are you trying to do?

-Gyepi

[Juan Torres]

Hello, i´m trying to use the package kv (https://github.com/cznic/kv) and the method Set and the param is a array byte 

func (db *DB) Set(key, value []byte) (err error) {

...

}

and i would like to convert one structure to array byte.. 

[Juan Torres]

Finally, the possible solution is convert the struct to json and generate the binary  but i´m sure that is not the best solution (efficient)

buf := new(bytes.Buffer)

    var number Number

    key := "1"

    number.One = key

    number.Two = "2"

    b, err := json.Marshal(number)

    if err != nil {

        fmt.Printf("Error: %s", err)

        return

    }

    fmt.Println(string(b))

    err = binary.Write(buf, binary.BigEndian, &b)

[Gyepi SAM]

On Mon, Mar 31, 2014 at 08:39:20AM -0700, Juan Torres wrote:
> Hello, i´m trying to use the package kv (https://github.com/cznic/kv) and
> the method Set and the param is a array byte
>
> func (db *DB) Set(key, value []byte) (err error) {
> ...
> }
> and i would like to convert one structure to array byte..

Given the data store, I assume your program is the only consumer
of the encoded values. In that case encoding/gob
should work fine for you. Here's a usage example.

http://play.golang.org/p/frZq8YbcAb

Just FYI, there are other encoding mechanisms as well: json, bson, msgpack,
etc, etc. Depending on who else needs to read the data (humans included),
one or the other may be a better fit, but the process is about the same
in all cases.

-Gyepi

[Gyepi SAM]

> err = binary.Write(buf, binary.BigEndian, &b)

This line is not necessary and is actually nonsensical.
b is of type []byte and already contains the value you need to store.
No need to involve binary at all.

-Gyepi