Golang : Convert(cast) bytes.Buffer or bytes.NewBuffer type to io.Reader



Tags : golang bytes-buffer io-reader convert-cast

Problem :

You need to convert or type cast bytes.Buffer or bytes.NewBuffer type to io.Reader to use in io.MultiReader() function because of this error :

cannot use buffer_slice (type []*bytes.Buffer) as type io.Reader in argument to io.MultiReader: []*bytes.Buffer does not implement io.Reader (missing Read method).

Solution :

Wrap the bytes.Buffer with io.Reader array. For example :

 package main

 import (
 "bytes"
 "fmt"
 "io"
 "io/ioutil"
 )

 func main() {

 readerBuffer := bytes.NewBuffer([]byte("abcdefghijkl"))

 readerBuffer2 := bytes.NewBuffer([]byte("mnopqrstuvwxyz"))

 buff := []io.Reader{readerBuffer, readerBuffer2} // <------ here 

 combined := io.MultiReader(buff...)

 data, _ := ioutil.ReadAll(combined)

 fmt.Println(string(data))
 }

or

 package main

 import (
 "bytes"
 "fmt"
 "io"
 "io/ioutil"
 )

 func main() {

 //readerBuffer := bytes.NewBuffer([]byte("abcdefghijkl"))

 readerBuffer := &bytes.Buffer{}
 readerBuffer.Write([]byte("abcdefghijkl"))

 //readerBuffer2 := bytes.NewBuffer([]byte("mnopqrstuvwxyz"))

 readerBuffer2 := &bytes.Buffer{}
 readerBuffer2.Write([]byte("mnopqrstuvwxyz"))

 buff := []io.Reader{readerBuffer, readerBuffer2} // <------ here 

 combined := io.MultiReader(buff...)

 data, _ := ioutil.ReadAll(combined)

 fmt.Println(string(data))
 }

Reference :

https://socketloop.com/references/golang-io-multireader-function-example

  See also : Golang : Convert(cast) []byte to io.Reader type



Tags : golang bytes-buffer io-reader convert-cast

By Adam Ng

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