How to upload file to amazon s3 using gin framework - go

Question

I am trying to upload a file to Amazon S3 Using gin framework of Go. Since aws-sdc requires to read the file i need to open file using os.open('filename').But since i am getting the file from "formFile" I don't have the path of the file to open, so os.Open() is giving error
The system cannot find the file specified.
My approach is as follows
package controllers
import (
"bytes"
"log"
"net/http"
"os"
"github.com/gin-gonic/gin"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/credentials"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/s3"
)
const (
S3_REGION = "MY REGION"
S3_BUCKET = "<MY BUCKET>"
)
func UploadDocument(c *gin.Context) {
var Buf bytes.Buffer
file, _ := c.FormFile("file")
creds := credentials.NewSharedCredentials("", "default")
s, err := session.NewSession(&aws.Config{
Region: aws.String(S3_REGION),
Credentials: creds,
})
if err != nil {
log.Fatal(err)
}
err = AddFilesToS3(s, file.fileName)
if err != nil {
log.Fatal(err)
}
}
func AddFilesToS3(s *session.Session, fileDir string) error {
file, err := os.Open(fileDir)
if err != nil {
return err
}
defer file.Close()
fileInfo, _ := file.Stat()
var size int64 = fileInfo.Size()
buffer := make([]byte, size)
file.Read(buffer)
_, err = s3.New(s).PutObject(&s3.PutObjectInput{
Bucket: aws.String(S3_BUCKET),
Key: aws.String("myfolder" + "/" + fileDir),
ACL: aws.String("private"),
Body: bytes.NewReader(buffer),
ContentLength: aws.Int64(size),
ContentType: aws.String(http.DetectContentType(buffer)),
ContentDisposition: aws.String("attachment"),
ServerSideEncryption: aws.String("AES256"),
})
return err
}
I am sending my file through POSTMAN like this
what I need to pass to my 'AddFilesToS3' function, since I am sending just the file name, os.Open(fileDir) is failing to look to the actual path of the file.
Where am I doing wrong or is there any better method available to do this?

Answer 1

You're not even reading the file from the form.
You need to call FileHeader.Open. This returns a multipart.File which implements the standard io.Reader interface.
You should change AddFilesToS3 to take a filename and io.Reader. This can then be called for files from gin as well as regular files.
fileHeader, err := c.FormFile("file")
// check err
f, err := fileHeader.Open()
// check err
err = AddFilesToS3(s, fileHeader.fileName, f)
And your AddFilesToS3 is now:
func AddFilesToS3(s *session.Session, fileDir string, r io.Reader) error {
// left as an exercise for the OP
You may need to pass fileHeader.Size() as well.