Gulter is a Go HTTP middleware designed to simplify the process of uploading files
for your web apps. It follows the standard
http.Handler and http.HandlerFunc interfaces so you can
always use with any of framework or the standard library router.
Name and idea was gotten from the insanely popular multer package in Node.JS that does the same.
go get -u -v github.com/adelowo/gulterAssuming you have a HTML form like this:
<form action="/" method="post" enctype="multipart/form-data">
<input type="file" name="form-field-1" />
<input type="file" name="form-field-2" />
</form>To create a new Gulter instance, you can do something like this:
handler, _ := gulter.New(
gulter.WithMaxFileSize(10<<20),
gulter.WithValidationFunc(
gulter.ChainValidators(gulter.MimeTypeValidator("image/jpeg", "image/png"),
func(f gulter.File) error {
// Your own custom validation function on the file here
// Else you can really just drop the ChainValidators and use only the MimeTypeValidator or just
// one custom validator alone
return nil
})),
gulter.WithStorage(s3Store),
)The handler is really just a HTTP middleware with the following signature
Upload(keys ...string) func(next http.Handler) http.Handler. keys here
are the input names from the HTML form, so you can chain this into almost any HTTP
router,
package main
import (
"fmt"
"net/http"
"github.com/adelowo/gulter"
"github.com/adelowo/gulter/storage"
)
func main() {
s3Store, err := storage.NewS3FromEnvironment(storage.S3Options{
Bucket: "std-router",
})
if err != nil {
panic(err.Error())
}
// diskStore,err := storage.NewDiskStorage("/Users/lanreadelowo/gulter-uploads/")
handler, err := gulter.New(
gulter.WithMaxFileSize(10<<20),
gulter.WithStorage(s3Store),
)
mux := http.NewServeMux()
// upload all files with the "name" and "lanre" fields on this route
mux.Handle("/", handler.Upload("name", "lanre")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
fmt.Println("Uploaded file")
f, err := gulter.FilesFromContext(r)
if err != nil {
fmt.Println(err)
return
}
ff, err := gulter.FileFromContext(r, "lanre")
if err != nil {
fmt.Println(err)
return
}
fmt.Printf("%+v", ff)
for _, v := range f {
fmt.Printf("%+v", v)
fmt.Println()
}
})))
http.ListenAndServe(":3300", mux) s3Store, err := storage.NewS3FromEnvironment(storage.S3Options{
Bucket: "chi-router",
})
if err != nil {
panic(err.Error())
}
// diskStore,err := storage.NewDiskStorage("/Users/lanreadelowo/gulter-uploads/")
handler := gulter.New(
gulter.WithMaxFileSize(10<<20),
gulter.WithValidationFunc(gulter.ChainValidators(gulter.MimeTypeValidator("image/jpeg", "image/png"))),
gulter.WithStorage(s3Store),
)
router := chi.NewMux()
// upload all files in the form fields called "form-field-1" and "form-field-2"
router.With(handler.Upload("form-field-1", "form-field-2")).Post("/", func(w http.ResponseWriter, r *http.Request) {
fmt.Println("Uploaded file")
f, err := gulter.FilesFromContext(r)
if err != nil {
fmt.Println(err)
return
}
ff, err := gulter.FileFromContext(r, "form-field-1") // or form-field-2
if err != nil {
fmt.Println(err)
return
}
fmt.Printf("%+v", ff)
for _, v := range f {
fmt.Printf("%+v", v)
fmt.Println()
}
})While this middleware automatically uploads your files, sometimes you need details about the uploaded file to show to the user, this could be making up the image url or path to the image. To get that in your HTTP handler, you can use either:
FileFromContext: retrieve a named input uploaded file.FilesFromContext: retrieve all uploaded files
Gulter also ships with two storage implementations at the moment:
S3Store: supports S3 or any compatible service like MinioDiskStore: uses a local filesystem backed store to upload filesCloudinaryStore: uploads file to cloudinary