Say I have this route handler in my Express.js app:
app.get('/files/:name', function (req, res) {
res.sendfile('path/to/files/' + req.params.name + '.html');
});
This path is used via Ajax on my site. I wonder if I should guard against situations where a file with the requested name does not exist on the server, in which case the server returns a 404 response. I can work with this, i.e. detect the 404 in the browser and act accordingly (e.g. display a message to the visitor). However, I'm not sure if this is a good approach. Is it OK to use the 404 response here, or am I supposed to try to avoid 404 responses if possible. (E.g. I could if a file with the requested name exists on the server and only use .sendFile() if it does.)
I'm worried that performing a manual check would only slow things down as .sendFile() already has this check built-in (i.e. it's possible to avoid this check and instead detect 404 responses in the browser which is what I'm doing right now and it works fine).
I would stick with returning a 404 instead, as that's the 404's purpose.I'm not sure there really is any other common/practical alternative.
Good luck.
Related
I'm having a pretty weird problem with CORS on a webapp I'm trying to make
I'm using Servlets (Tomcat8.0) for the backend. It's a school project, so I can't use a framework
A GET request to http://localhost:8080/FileBox/dashboard
returns a JSON payload( plain json, not jsonp,which I could use, but its the same domain). I'm using ajax to make the XHR, but it's being blocked by chrome as CORS
Should this be happening, since I'm making the XHR from the same domain(host+port)
'localhost:8080/FileBox/dashboard.jsp'
to
'localhost:8080/FileBox/dashboard'
Please, and thank you for the help!
You aren't making a request to http://localhost:8080/FileBox/dashboard. The error message says you are making a cross-origin request using an unsupported scheme and that http is a supported scheme.
Presumably you have made the two mistakes of:
Getting the URL wrong
You should be using a relative URL:
/FileBox/dashboard
but are trying to use an absolute URL:
http://localhost:8080/FileBox/dashboard
but have typed it wrong and are actually requesting
localhost:8080/FileBox/dashboard
Not loading the page over HTTP to start with
Possibly by double clicking the file in your system file manager, you have bypassed your HTTP server and are loading something like file:///c:/users/you/yourproject/index.html
Combined with the previous mistake, you end up trying to request file:///c:/users/you/yourproject/localhost:8080/FileBox/dashboard, with Ajax and get a security violation.
Solution
Fix the URL to be a proper relative URL
Point your browser at http://localhost:8080 instead of double clicking files in your file manager
So I have been getting the infamous 404.3 error when trying to use AXAJ to access a .json file launching the site (or more of a test app hehe) through WebMatrix on localhost.
Yes, I am aware of the IIS configuration. I am on Windows 8.1(x64), so I had to even turn on MIME types functionality separately. I configured a MIME type for .json with application/javascript. Then I went and added a handler to *.json, pointed it to C:\WINDOWS\system32\inetsrv\asp.dll. I set the verbs to GET and POST (those are what I use in my ajax function). I also tried unchecking the "Invoke the handler only if request is mapped to..." to no avail.
I am using one function to send data to PHP file which writes it to the JSON file and then another to fetch data from the JSON file directly. Writing through PHP works. Fetching doesn't. I am completely at a loss, does anyone have any ideas? The code I am using to fetch the data is your bog-standard ajax:
function getDate(path, callback) {
var httpRequest = new XMLHttpRequest();
httpRequest.onreadystatechange = function() {
if (httpRequest.readyState === 4) {
if (httpRequest.status === 200) {
var data = JSON.parse(httpRequest.responseText);
if (callback) callback(data);
}
}
};
httpRequest.open('GET', path);
httpRequest.send();
}
When I host this on my server space, it works totally fine. But I want to get it to work locally for testing purposes as well.
If writing to the file works but fetching doesn't work. Then you should check for the link of the file.
The error 404 as the name refers to, is an error for the file name. There isn't any other sort of error, even the Ajax request is working fine and giving the error 404 (file not found). So the only thing that you can do is, to make sure that while fetching the data, you use the correct link.
Here can be a help, when you send the Request through Ajax, there is a Network tab in your Browser's console. Open it, and look for the request. It would in red color denoting an error and click it. You'll see that the link you're providing isn't valid.
Look for the errors in the File Link then and update it.
The lengths I go to, to clean up my profile...
When you require a JSON format, or any file for that matter you have to specify in your request what data type you need, IIS will not make any assumptions. So
xhr.setRequestProperty('Content-Type', 'application/json');
is something one must not forget. I set also the X-Requested-With header. Note that to reproduce this issue I used IIS that is installed on Windows 10 Pro, so not exactly the same system (3 years later - holy crap!).
I have strange problem with CodeIgniter and routing system and can't find solution for it, so: I have several routes such as
'forum/(:num)'
=> 'forum/category/$1',
'forum/(:num)/(page:any)'
=> 'forum/category/$1/$2',
and them works, but return 404 code in header.
I mean I don't get 404 page, correct HTML returns and page's content displays correctly for my forum's categories. But I'm getting 404 in header (Network tab in Firebug), so I can't work with POST data correctly.
If I request /forum/ - 200 Ok returns, but when I trying to get routed page, I get right page, but with 404 Not Found.
I'm using PHP5.4+Apache2 on Linux host, if it will help You to give me solution.
I've found solution! Maybe it will save someone's time.
Problem wasn't in CodeIgniter, I've found solution in activation mod_rewrite. Yes, that worked, but wan't activated in Apache.
Just try to do
sudo a2enmod rewrite
and restart apache service after
sudo service apache restart
And all routed pages will return 200 Ok
None of these worked, but I did this instead:
At the end of my controller I put this:
$this->output->set_status_header('200');
and actually though that worked, the problem turned out to be a controller name that conflicted with a real directory name...
I am creating a simulation game (web service), and need to fake those error pages. As far as I know, and can see, there isn't a way to fake a 404, or 500 etc. Is this right? Are we able to do this programmatically?
I know I could just make a 404 page and redirect to it... But I'm trying to make it a little more realistic.
Returning a 404 or 500 status code to the browser (see your programming language's/framework's documentation for how) will send a real one instead of a fake one.
Copy whatever page your server sends for those particular errors (or just read the existing files if you've specified them explicitly) and write that out, then send the right status code along with it. For example, in PHP:
header("HTTP/1.1 500 Internal Server Error");
Here's how I'd do it using PHP:
<?php
header('HTTP/ 404'); //So that the browser thinks it's a legitimate 404 error.
#readfile($_SERVER['DOCUMENT_ROOT'] . '/404.html') or die('404 Not Found'); //Replace "/404.html" with your 404 page.
?>
I am getting this Error
NETWORK_ERROR: XMLHttpRequest Exception 101
when trying to get XML content from one site.
Here is my code:
var xmlhttp;
if(window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
}
if (xmlhttp==null) {
alert ("Your browser does not support XMLHTTP!");
return;
}
xmlhttp.onReadyStateChange=function() {
if(xmlhttp.readyState==4) {
var value =xmlhttp.responseXML;
alert(value);
}
}
xmlhttp.open("GET",url,false);
xmlhttp.send();
//alert(xmlhttp.responseXML);
}
xmlhttp.open("GET",url,false);
xmlhttp.send(null);
Does any one have a solution?
If the url you provide is located externally to your server, and the server has not allowed you to send requests, you have permission problems. You cannot access data from another server with a XMLHttpRequest, without the server explicitly allowing you to do so.
Update: Realizing this is now visible as an answer on Google, I tried to find some documentation on this error. That was surprisingly hard.
This article though, has some background info and steps to resolve. Specifically, it mentions this error here:
As long as the server is configured to allow requests from your web application's origin, XMLHttpRequest will work. Otherwise, an INVALID_ACCESS_ERR exception is thrown
An interpretation of INVALID_ACCESS_ERR seems to be what we're looking at here.
To solve this, the server that receives the request, must be configured to allow the origin. This is described in more details at Mozilla.
The restriction that you cannot access data from another server with a XMLHttpRequest can apply even if the url just implies a remote server.
So:
url = "http://www.myserver.com/webpage.html"
may fail,
but:
url = "/webpage.html"
succeed - even if the request is being made from www.myserver.com
Request aborted because it was cached or previously requested? It seems the XMLHttpRequest Exception 101 error can be thrown for several reasons. I've found that it occurs when I send an XMLHttpRequest with the same URL more than one time. (Changing the URL by appending a cache defeating nonsense string to the end of the URL allows the request to be repeated. -- I wasn't intending to repeat the request, but events in the program caused it to happen and resulted in this exception).
Not returning the correct responseText or responseXML in the event of a repeated request is a bug (probably webKit).
When this exception occurred, I did get an onload event with readyState==4 and the request object state=0 and responseText=="" and responseXML==null. This was a cross domain request, which the server permits.
This was on an Android 2.3.5 system which uses webKit/533.1
Anyone have documentation on what the exception is supposed to mean?
Something like this happened with me when I returned incorrect XML (I put an attribute in the root node). In case this helps anyone.
xmlhttp.open("GET",url, true);
set the async part to true
I found a very nice article with 2 diferent solutions.
The first one implementing jQuery and JSONP, explaining how simple it is.
The second approach, it's redirecting trough a PHP call. Very simple and very nice.
http://mayten.com.ar/blog/42-ajax-cross-domain
Another modern method of solving this problem is Cross Origin Ressource Sharing.
HTML5 offers this feature. You can "wrap" your XMLhttp request in this CORS_request and
if the target browser supports this feature, you can use it and wont have no problems.
EDIT:
Additionaly i have to add that there are many reasons which can cause this Issue.
Not only a Cross Domain Restriction but also simply wrong Settings in your WEB.CONFIG of your Webservice.
Example IIS(.NET):
To enable HTTP access from external sources ( in my case a compiled Phonegap app with CORS request ) you have to add this to your WEB.CONFIG
<webServices>
<protocols>
<add name="HttpGet"/>
<add name="HttpPost"/>
</protocols>
</webServices>
Another scenario:
I got two webservices running... One on Port 80 and one on Port 90. This also gave me an XML HTTP Request Error. I even dont know why :). Nevertheless i think this can help many not well experienced readers.