I can't seem to get my "download file" feature working using Expressjs.
//DOWNLOAD FILE
router.get('/snippets/download', function (req, res) {
res.attachment("untitled.js");
res.send("here is some javascript");
});
If I access this route in my browser the file downloads to my computer but not if I use an Angularjs request to the route.
Am I missing something?
You can use res.download. Refer documentation here: http://expressjs.com/4x/api.html
Eg:
//DOWNLOAD FILE
router.post('/snippets/download', function (req, res) {
res.download(req.body.filename, req.body.text);
});
See if this helps.
The res.download() method need a file's full path ( which could be different in windows and linux with different seperator ).
And the 2nd param of res.download(localName, downloadPromptName ) should be able to modify the filename that user see (different from the file in your server's directory), but it seems that does not work in my environment.
So I recommend you to use res.sendFile(fullNameInServer ,options) where you can modify the downloaded filename in options.
var root = getDownloadRoot(req);
var options = {
root: getDownloadRoot(req),
headers: {
"content": "text/html;charset=utf-8",
"Content-Type": "application/octet-stream",
"Expires":"0",
"Cache-Control": "must-revalidate, post-check=0, pre-check=0",
"content-disposition": "attachment;filename=" + urlencode(downloadFilename)
}
};
res.sendFile( tempFileName ,options);
urlencode should be required to encode filename then you can use filename other than english.
before call download file , you need to write the file physically in a temp folder,
the getDownloadRoot() method give you the temp folder location in runtime which does not vary when you change the path to run the app.
here is the function getDownloadRoot()
function getDownloadRoot(req){
var path = require('path');
var sep = path.sep;
var parentPath = path.dirname(req.settings.views);
var ret = parentPath.concat(sep + tempFileFolder);
return ret;
}
For now I have no way other than using app.setting (that app is declared in app.js) to get the application folder during runtime. So I made a litte 'middleware' to transport the value with req object as following.
In app.js:
app.use(function(req, res, next) {
req.settings = app.settings;
next();
});
tempFileFolder is a folder that you can name it yourself.
sep is the folder seperator ( \ in windows and / in linux )
Also you need to watch the folder permission settings when running in linux.
This combination works perfectly in my environment (with angularjs)
Related
I have a function that allows you to create a folder in the directory where the server is located, and upload files there
And I'm trying to access them via a direct link, like this
http://localhost:5000/attachments/1618413024408--1.jpg
Because, the file is located here
But why can't I access it?
Cannot GET /attachments/1618413024408--1.jpg
Express itself provides an easy to use implementation for this express.static(root, [options]).
Simply add this add the right position in your code:
app.use('/attachments', express.static(path.join(__dirname, 'attachments')))
Make sure that path.join(__dirname, 'attachments') points to the right directory (with a simple console.log) otherwise just adjust it.
Documentation: https://expressjs.com/en/starter/static-files.html
try to use express function sendFile
https://expressjs.com/en/api.html#res.sendFile
something like this
app.use('/attachments/:filename', (req, res) => {
const myIms = <path to directory>
const filePath = myIms + '/attachments/' + req.filename
res.sendFile(filePath, {
headers: {
'Content-Type': 'image/jpg'
}
})
})
or express download function https://expressjs.com/en/api.html#res.download
I've set up a small node js BE app, built with express and fastCsv module on top of it. The desired outcome would be to be able to download a csv file to the client side, without storing it anywhere inside the server, since the data is generated depending on user criteria.
So far I've been able to get somewhere it it, Im using streams, since that csv file could be pretty large depending on the user selection. Im pretty sure something is missing inside the code bellow:
const fs = require('fs');
const fastCsv = require('fast-csv');
.....
(inside api request)
.....
router.get('/', async(req, res) => {
const gatheredData ...
const filename = 'sometest.csv'
res.writeHead(200, {
'Content-Type': 'text/csv',
'Content-Disposition': 'attachment; filename=' + filename
})
const csvDataStream = fastCsv.write(data, {headers: true}).pipe(res)
})
The above code 'works' in some way as it does deliver back the response, but not the actual file, but the contents of the csv file, which I can view in the preview tab as a response. To sum up, Im trying to stream in that data, into a csv and push it to download file to client, and not store it on the server. Any tips or pointers are very much appreciated.
Here's what worked for me after created a CSV file on the server using the fast-csv package. You need to specify the full, absolute directory path where the output CSV file was created:
const csv = require("fast-csv");
const csvDir = "abs/path/to/csv/dir";
const filename = "my-data.csv";
const csvOutput = `${csvDir}/${filename}`;
console.log(`csvOutput: ${csvOutput}`); // full path
/*
CREATE YOUR csvOutput FILE USING 'fast-csv' HERE
*/
res.type("text/csv");
res.header("Content-Disposition", `attachment; filename="${filename}"`);
res.header("Content-Type", "text/csv");
res.sendFile(filename, { root: csvDir });
You need to make sure to change the response content-type and headers to "text/csv", and try enclosing the filename=... part in double-quotes, like in the above example.
In our application we store our reports in a user defined folders. User can add their own folders during runtime. Iam showing the history of those files in a web page. on clicking the file name i should show the file from the folder. How can i show the files from a non public directory.Since its given during runtime i havent added them as static dir to the express server.
One idea we tried was to use node-static-server and create a file server with the folder and serve the file. for each file we create this. it works fine but i get an error saying "port already in use". is there any better idea to do this? is this the right approach?
You can do this in NodeJS using a express.static:
const FS = require('fs')
const express = require('express')
const bp = require('body-parser')
const app = express()
function fileTest(req, res, next){
if (/\.|\/|\\/.test(req.params.file))
return res.sendStatus(400)
return next();
}
app.get(
'/static/:file',
fileTest,
function(req, res, next){
req.url = req.url.replace('/static','')
next()
},
express.static(
'./static',
{
fallthrough: false
}
)
)
app.post(
'/static/:file',
fileTest,
bp.text(),
function (req, res) {
FS.writeFile(
'./static/'+req.params.file,
req.body,
function (err) {
if(err)
return res.sendStatus(500)
return res.sendStatus(200)
}
)
}
)
app.listen(
1337
)
This is a simple example showing a server that will:
[POST]
Take a text body and load it into memory( pitfall: large bodies in memory )
Based on the URL, save it as a file in the static folder
[GET]
Search for a file
If found return file
The good news is that you can make the file and then request the file without restarting the server. Bad news is that this is a VERY SLOW server( comparatively to other options ).
As with all examples no good practices were followed, so be sure to adapt it to your needs.
Things to think about as you adopt it:
How do I allow people to save files to other folders?
How do I disallow people from saving files to other folders I don't want them to?
PROPER AUTHORIZATION
I have a webpage that I have hosted using a node application on openshift. Its here
http://nodejs-volition.rhcloud.com/
My question is very simple (although I haven't found anyone else asking it). How do I refer to other files in the directory which contains index.html
For instance I would like to use an image that is in the directory in the index. My current html for the image is
<img src="$OPENSHIFT_REPO_DIR/images/1416870991752.jpg" alt="spark core">
I have also tried using "images/1416870991752.jpg". I have the same problem with linking to other html files in the directory?
What am I doing wrong? Please help?
As corey112358 alludes to below the key is in that to host using nodejs a server must be defined. My application already has a server file, so rather than creating a new server I must modify the existing one. I've done it successfully now, there were two changes to make to the server.js file.
The 1st change is modification of the cache. That should look like this...
self.zcache['index.html'] = fs.readFileSync('./index.html');
self.zcache['page2.html'] = fs.readFileSync('./page2.html');
self.zcache['sparkcoredark.jpg'] = fs.readFileSync('./sparkcoredark.jpg');
The first line was already included but the next two were added by me to include another html page and an image.
The second step is modify the self.createRoutes section of the server.js file as below (asciimo image is included by default).
self.createRoutes = function() {
self.routes = { };
self.routes['/asciimo'] = function(req, res) {
var link = "http://i.imgur.com/kmbjB.png";
res.send("<html><body><img src='" + link + "'></body></html>");
};
self.routes['/'] = function(req, res) {
res.setHeader('Content-Type', 'text/html');
res.send(self.cache_get('index.html') );
};
self.routes['/page2.html'] = function(req, res) {
res.setHeader('Content-Type', 'text/html');
res.send(self.cache_get('page2.html') );
};
self.routes['/sparkcoredark.jpg'] = function(req, res) {
res.setHeader('Content-Type', 'image/jpg');
res.send(self.cache_get('sparkcoredark.jpg') );
};
};
Hope that helps out anyone else struggling with this issue. Thanks to coreyfibonacci
I was under the impression that when you run a nodejs webserver the root of the web is the folder containing the js file implementing the webserver. So if you have C:\foo\server.js and you run it, then "/" refers to C:\foo and "/index.htm" maps to C:\foo\index.htm
I have a file server.js with a sibling file default.htm, but when I try to load the contents of /default.htm the file is not found. An absolute file path works.
Where is "/" and what controls this?
Working up a repro I simplified it to this:
var fs = require('fs');
var body = fs.readFileSync('/default.htm');
and noticed it's looking for this
Error: ENOENT, no such file or directory 'C:\default.htm'
So "/" maps to C:\
Is there a way to control the mapping of the web root?
I notice that relative paths do work. So
var fs = require('fs');
var body = fs.readFileSync('default.htm');
succeeds.
I believe my confusion arose from the coincidental placement of my original experiment's project files at the root of a drive. This allowed references to /default.htm to resolve correctly; it was only when I moved things into a folder to place them under source control that this issue was revealed.
I will certainly look into express, but you haven't answered my question: is it possible to remap the web root and if so how?
As a matter of interest this is server.js as it currently stands
var http = require('http');
var fs = require('fs');
var sys = require('sys');
var formidable = require('formidable');
var util = require('util');
var URL = require('url');
var QueryString = require('querystring');
var mimeMap = { htm : "text/html", css : "text/css", json : "application/json" };
http.createServer(function (request, response) {
var body, token, value, mimeType;
var url = URL.parse(request.url);
var path = url.pathname;
var params = QueryString.parse(url.query);
console.log(request.method + " " + path);
switch (path) {
case "/getsettings":
try {
mimeType = "application/json";
body = fs.readFileSync("dummy.json"); //mock db
} catch(exception) {
console.log(exception.text);
body = exception;
}
break;
case "/setsettings":
mimeType = "application/json";
body="{}";
console.log(params);
break;
case "/":
path = "default.htm";
default:
try {
mimeType = mimeMap[path.substring(path.lastIndexOf('.') + 1)];
if (mimeType) {
body = fs.readFileSync(path);
} else {
mimeType = "text/html";
body = "<h1>Error</h1><body>Could not resolve mime type from file extension</body>";
}
} catch (exception) {
mimeType = "text/html";
body = "<h1>404 - not found</h1>" + exception.toString();
}
break;
}
response.writeHead(200, {'Content-Type': mimeType});
response.writeHead(200, {'Cache-Control': 'no-cache'});
response.writeHead(200, {'Pragma': 'no-cache'});
response.end(body);
}).listen(8124);
console.log('Server running at http://127.0.0.1:8124/');
I'm not completely certain what you mean by "routes" but I suspect that setsettings and getsettings are the sort of thing you meant, correct me if I'm wrong.
Nodejs does not appear to support arbitrary mapping of the web root.
All that is required is to prepend absolute web paths with a period prior to using them in the file system:
var URL = require('url');
var url = URL.parse(request.url);
var path = url.pathname;
if (path[0] == '/')
path = '.' + path;
While you're correct that the root of the server is the current working directory Node.js won't do a direct pass-through to the files on your file system, that could be a bit of a security risk after all.
Instead you need to provide it with routes that then in turn provide content for the request being made.
A simple server like
var http = require('http');
http.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello World\n');
}).listen(1337, '127.0.0.1');
Will just capture any request and respond in the same way (but doesn't read the file system).
Now if you want to serve out file contents you need to specify some way to read that file into the response stream, this can be done a few ways:
You can use the fs API to find the file on disk, read its contents into memory and then pipe them out to the response. This is a pretty tedious approach, especially when you start getting a larger number of files, but it does allow you very direct control over what's happening in your application
You can use a middleware server like express.js, which IMO is a much better approach to do what you're wanting to do. There's plenty of questions and answers on using Express here on StackOverflow, this is a good example of a static server which is what you talk about
Edit
With the clarification of the question the reason:
var body = fs.readFileSync('/default.htm');
Results in thinking the file is at C:\default.htm is because you're using an absolute path not a relative path. If you had:
var body = fs.readFileSync('./default.htm');
It would then know that you want to operate relative to the current working directory. / is from the root of the partition and ./ is from the current working directory.