README
¶
UploadHandler
Purpose
Sometimes a web-server application needs a way to accept file uploads from the remote users. This package does just this: it accepts uploads (up to a certain size) and stores them in a configurable directory.
Installation
You can use Go to install this package for you:
go get -u github.com/mwat56/go-uploadhandler
Usage
The main function to call is
// Wrap returns a handler function that includes error page handling,
// wrapping the given `aHandler` and calling it internally.
//
func Wrap(aHandler http.Handler,
aDestDir, aFieldName, anUpURL, aNextURL string,
aMaxSize int64, aPager errorhandler.TErrorPager) http.Handler {…}
While at first glance the number of arguments seems to be overwhelming they allow you to fully configure the package's behaviour when an uploaded file arrives. Let's look at the arguments one by one:
aHandleris the handler function which you're already using for your web-server. It will continue to work as it used to before except that a certain URL (configred byanUpURL, see below) will be intercepted if something gets POSTed to it.aDestDiris the directory where the incoming file is finally stored after processing it.aFieldNameis the name/ID of the form/field your web-page uses to accept the file-upload.anUpURLis the URL your web-page'sFORMelement POSTs its data to. This URL will be intercepted (if it's accessed by the POST HTTP method) and its data will be proccessed.aNextURLis the URL the user get's forwarded to after the file upload was successfully processed.aMaxSizedefines the max. accepted size of uploaded files. Files bigger than that value will be rejected. Think carefully about which size will suit your actual needs.aPageris an optional provider of error message pages (ornilif not needed). – See github.com/mwat56/go-errorhandler for details about that package.
Here is a very simple example using this package:
func testHandler(aWriter http.ResponseWriter, aRequest *http.Request) {
// the upload form to show
page := `<!DOCTYPE html><html><head><title>Go Upload</title></head><body>
<form action="/up" method="post" enctype="multipart/form-data">
<p><label for="uploadFile">Filename:</label>
<input type="file" name="uploadFile" id="uploadFile"></p>
<p><input type="submit" name="submit" value="Submit"></p>
</form></body></html>`
// send it to the remote user:
aWriter.WriteHeader(200)
aWriter.Write([]byte(page))
// POST is handled by the UploadHandler
} // testHandler()
func main() {
// let the upload handler wrap our own page handler:
handler := uploadhandler.Wrap(http.HandlerFunc(testHandler),
"./static", "uploadFile", "up", "/", 10*1024*1024, nil)
if err := http.ListenAndServe("127.0.0.1:8080", handler); nil != err {
log.Fatalf("%s Problem: %v", os.Args[0], err)
}
} // main()
You'll probably save the required values for e.g. aDestDir and aMaxSize in some kind of config-file, reading them at start of your web-server, and passing them along to the final Wrap() call instead of hard-coding them like in the example above.
And the values of anUpURL and aFieldName must, obviously, correspond with those you're actually using in your own application.
If you don't use customised error pages you can pass nil for the aPager argument as done in the example.
So, to add the file-upload functionality to your web-server application all that's needed is a single Wrap() function call. That's it.
Licence
Copyright © 2019 M.Watermann, 10247 Berlin, Germany
All rights reserved
EMail : <support@mwat.de>
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.
This software is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
You should have received a copy of the GNU General Public License along with this program. If not, see the GNU General Public License for details.
Documentation
¶
Overview ¶
Package uploadhandler implements a simple handler for HTTP file uploads.
Copyright © 2019 M.Watermann, 10247 Berlin, Germany
All rights reserved
EMail : <support@mwat.de>
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.
This software is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
You should have received a copy of the GNU General Public License along with this program. If not, see the [GNU General Public License](http://www.gnu.org/licenses/gpl.html) for details.
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func Wrap ¶
func Wrap(aHandler http.Handler, aDestDir, aFieldName, anUpURL, aNextURL string, aMaxSize int64, aPager errorhandler.TErrorPager) http.Handler
Wrap returns a handler function that includes error page handling, wrapping the given `aHandler` and calling it internally.
`aHandler` the previous handler responding to the HTTP request.
`aDestDir` is the directory to place the uploaded files.
`aFieldName` the name/ID of the form/input holding the uploaded file.
`anUpURL` the URL uploads are POSTed to.
`aNextURL` the URL to redirect the user after a asuccessful upload.
`aMaxSize` the max. accepted size of uploaded files.
`aPager` optional provider of error message pages (or `nil` if not needed).
Types ¶
type TUploadHandler ¶
type TUploadHandler struct {
// contains filtered or unexported fields
}
TUploadHandler embeds a `TErrorPager` which provides error page handling.
func NewHandler ¶
func NewHandler(aDestDir, aFieldName, anUpURL, aNextURL string, aMaxSize int64, aPager errorhandler.TErrorPager) *TUploadHandler
NewHandler returns a new `tUploadHandler` instance.
`aDestDir` is the directory to place the uploaded files.
`aFieldName` the name/ID of the form/input holding the uploaded file.
`anUpURL` the URL uploads are POSTed to.
`aNextURL` the URL to redirect the user after a asuccessful upload.
`aMaxSize` the max. accepted size of uploaded files.
`aPager` optional provider of error message pages (or `nil` if not needed).
func (TUploadHandler) ServeHTTP ¶
func (uh TUploadHandler) ServeHTTP(aWriter http.ResponseWriter, aRequest *http.Request) (string, int)
ServeHTTP handles the incoming file upload.
`aWriter` writes the response to the remote user.
`aRequest` is the incoming upload request.
Source Files
Directories