如何使用Golang从Mongo GridFS下载文件？

Question

I am trying to write a Rest API which has a basic file upload, download. I am able to do the upload part just fine but I am having a hard time downloading file from gridfs. ANy suggestions ?

Answer 1

UPDATE: I think I figured out how to do it. I am curious if any one has any other suggestions:

Here is how it looks for me right now:

func DownloadRecord(w http.ResponseWriter, filename string) error {
    if !fileExists(filename) {
      return errors.New("File doesn't exist. Nothing to download")
    }
    session := sqlconnecter.GetMongoDBConnection()
    fileDb := session.DB("mydatabase")
    file, err := fileDb.GridFS("fs").Open(filename)
    defer file.Close()
    if err != nil {
      return err
    }
    fileHeader := make([]byte, 512)
    file.Read(fileHeader)
    fileContentType := http.DetectContentType(fileHeader)
    fileSize := file.Size()

    w.Header().Set("Content-Disposition", "attachment; filename="+filename)
    w.Header().Set("Content-Type", fileContentType)
    w.Header().Set("Content-Length", strconv.FormatInt(fileSize, 10))

    file.Seek(0, 0)
    io.Copy(w, file)
    return err
}