golang unzip Response.Body - go

Question

I wrote a little web crawler and had known that the Response is a zip file.
In my limited experience with golang programing, I only know how to unzip a existing file.
Can I unzip the Response.Body in memory without saving it in hard disk in advance?

Answer 1

Updating answer for handling Zip file response body in-memory.
Note: Ensure you have sufficient memory for handling zip file.
package main
import (
"archive/zip"
"bytes"
"fmt"
"io/ioutil"
"log"
"net/http"
)
func main() {
resp, err := http.Get("zip file url")
if err != nil {
log.Fatal(err)
}
defer resp.Body.Close()
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
log.Fatal(err)
}
zipReader, err := zip.NewReader(bytes.NewReader(body), int64(len(body)))
if err != nil {
log.Fatal(err)
}
// Read all the files from zip archive
for _, zipFile := range zipReader.File {
fmt.Println("Reading file:", zipFile.Name)
unzippedFileBytes, err := readZipFile(zipFile)
if err != nil {
log.Println(err)
continue
}
_ = unzippedFileBytes // this is unzipped file bytes
}
}
func readZipFile(zf *zip.File) ([]byte, error) {
f, err := zf.Open()
if err != nil {
return nil, err
}
defer f.Close()
return ioutil.ReadAll(f)
}
By default Go HTTP client handles Gzip response automatically. So do typical read and close of response body.
However there is a catch in it.
// Reference https://github.com/golang/go/blob/master/src/net/http/transport.go
//
// DisableCompression, if true, prevents the Transport from
// requesting compression with an "Accept-Encoding: gzip"
// request header when the Request contains no existing
// Accept-Encoding value. If the Transport requests gzip on
// its own and gets a gzipped response, it's transparently
// decoded in the Response.Body. However, if the user
// explicitly requested gzip it is not automatically
// uncompressed.
DisableCompression bool
What it means is; If you add a header Accept-Encoding: gzip manually in the request then you have to handle Gzip response body by yourself.
For Example -
reader, err := gzip.NewReader(resp.Body)
if err != nil {
log.Fatal(err)
}
defer reader.Close()
body, err := ioutil.ReadAll(reader)
if err != nil {
log.Fatal(err)
}
fmt.Println(string(body))