Local Storage in HTML5 - html

I am saving a value in the local storage (html 5) in page 1 and then when i go to page 2, the values in the localstorage are gone. Could you please let me know what could be the issue?
Editing
I am actually using the following functions to set the data on the local storage
function set(key, data)
{
localStorage.setItem(key, data);
}
function get(key)
{
return localStorage.getItem(key); }
function remove(key) {
localStorage.removeItem(key); }
function clear() {
localStorage.clear();
}
I have issues getting it to work on Firefox and dont have any issues on Chrome. This looks like an entirely different issue.
Thanks and Regards
Abishek R Srikaanth

You don't provide enough detail to troubleshoot this properly, but check these things out:
Are you previewing your design locally (e.g. via the file:// protocol), or are you on a proper web server? Only http:// requests will work accurately for you
Local storage and Web SQL storage work by reference to the originating domain or IP address (again why point #1 is important): is your second page still in scope?
What happens when you go back to page 1? Do the values re-appear?

Related

Couchbase Sync-Gateway Multiple Clients

I'am currently playing around with the Couchbase Sync-Gateway and have built a demo app.
What is the intended behavior if a user logs in with the same username on a different device (which has an empty database) or if he deleted the local database?
I'am expecting that all the data from the server should get synced back to the clients.
Is this correct?
My problem is that if i'am deleting the database or login from a different device, nothing will get synced.
Ok i figured it out and it's exactly how i thought it would be.
If i log in from a different device i get all the data synced automatically.
My problem was the missing sync function. I thought it will use a default and route all documents to the public channel automatically.
I'am now using the following simple sync-function:
"sync": `function (doc, oldDoc) {
channel('!');
access('demo#example.com', '*');
}`
This will simply route all documents to the public channel and grant my demo-user access to it.
I think this shouldn't be used in production but it's a good starting point for playing around.
Now everything is working fine.
Edit: I've now found the missing info:
https://docs.couchbase.com/sync-gateway/current/configuration-properties.html#databases-this_db-sync
If you don't supply a sync function, Sync Gateway uses the following default sync function
...
The channels property is an array of strings that contains the names of the channels to which the document belongs. If you do not include a channels property in a document, the document does not appear in any channels.

Interrupted downloads when downloading a file from Web Api (remote host closed error 0x800704CD)

I have read near 20 other posts about this particular error, but most seem to be issues with the code calling Response.Close or similar, which is not our case. I understand that this particular error means that typically a user browsed away from the web page or cancelled the request midway, but in our case we are getting this error without cancelling a request. I can observe the error just after a few seconds, the download just fails in the browser (both Chrome and IE, so it's not browser specific).
We have a web api controller that serves a file download.
[HttpGet]
public HttpResponseMessage Download()
{
//
// Enumerates a directory and returns a Read-only FileStream of the download
var stream = dataProvider.GetServerVersionAssemblyStream(configuration.DownloadDirectory, configuration.ServerVersion);
if (stream == null)
{
return new HttpResponseMessage(HttpStatusCode.NotFound);
}
var response = new HttpResponseMessage(HttpStatusCode.OK)
{
Content = new StreamContent(stream)
};
response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");
response.Content.Headers.ContentDisposition.FileName = $"{configuration.ServerVersion}.exe";
response.Content.Headers.ContentType = new MediaTypeHeaderValue(MediaTypeNames.Application.Octet);
response.Content.Headers.ContentLength = stream.Length;
return response;
}
Is there something incorrect we are doing in our Download method, or is there something we need to tweak in IIS?
This happens sporadically. I can't observe a pattern, it works sometimes and other times it fails repeatedly.
The file download is about 150MB
The download is initiated from a hyperlink on our web page, there is no special calling code
The download is over HTTPS (HTTP is disabled)
The Web Api is hosted on Azure
It doesn't appear to be timing out, it can happen just after a second or two, so it's not hitting the default 30 second timeout values
I also noticed I can't seem to initiate multiple file downloads from the server at once, which is concerning. This needs to be able to serve 150+ businesses and multiple simultaneous downloads, so I'm concerned there is something we need to tweak in IIS or the Web Api.
I was able to finally fix our problem. For us it turned out to be a combination of two things: 1) we had several memory leaks and CPU intensive code in our Web Api that was impacting concurrent downloads, and 2) we ultimately resolved the issue by changing MinBytesPerSecond (see: https://blogs.msdn.microsoft.com/benjaminperkins/2013/02/01/its-not-iis/) to a lower value, or 0 to disable. We have not had an issue since.

Dojo 1.9 JsonRest remote url on a different server

I'm trying to get dojo to show Json data that comes from a remote web service. I need to be clear though - the web server hosting the html/dojo page I access isn't the same server as the one that's running the web service that returns the json data - the web service server just can't serve html pages reliably (don't ask!!).
As a test I move the page into the same web server as the web service and the below works. As soon as I move it back so that the html/dojo is served from Apache (//myhost.nodomain:82 say) and the web service sending the json is "{target:http://myhost.nodomain:8181}", then it stops working.
I've used FFox to look at the network & I see the web service being called ok, the json data is returned too & looks correct (I know it is from the previous test), but the fields are no longer set. I've tried this with DataGrid and the plain page below with the same effects.
Am I tripping up over something obvious???
Thanks
require([
"dojo/store/JsonRest",
"dojo/store/Memory",
"dojo/store/Cache",
"dojox/grid/DataGrid",
"dojo/data/ObjectStore",
"dojo/query",
"dojo/domReady!"
],
function(JsonRest, Memory, Cache, DataGrid, ObjectStore, query) {
var myStore, dataStore, grid;
myStore = JsonRest(
{
target: "http://localhost:8181/ws/job/definition/",
idProperty: "JOB_NAME"
}
);
myStore.query("JOB00001"
).then(function(results) {
var theJobDef = results[0];
dojo.byId("JOB_NAME").innerHTML = theJobDef.JOB_NAME;
dojo.byId("SCHEDULED_DAYS").innerHTML = theJobDef.SCHEDULED_DAYS;
});
}
);
Its true what Frans said about the cross domain restriction but dojo has this link to work around the problem.
require(["dojo/request/iframe"], function(iframe){
iframe("something.xml", {
handleAs: "json"
}).then(function(xmldoc){
// Do something with the XML document
}, function(err){
// Handle the error condition
});
// Progress events are not supported using the iframe provider
});
you can simply use this and the returned data can be inserted into a store and then into the grid.
Are you familiar with the Same Origin Policy:
http://en.wikipedia.org/wiki/Same-origin_policy
Basically it restricts websites to do AJAX requests to other domains than the html page was loaded from. Common solutions to overcome this are CORS and JSON-P. However, remember that these restrictions are made for security reasons.

MvxDynamicImageHelper unreliable

I have an Mvx base iOS project which is having problems with image downloads.
I have a couple of screens which contain UICollectionViews and the UICollectionViewCells use MvxDynamicImageHelpers to set the Image of their UIImageViews to images hosted on the internet (Azure blob storage via Azure CDN in actual fact). I have noticed that the images sometimes do not appear and that this is more common on a slow connection and if I scroll through the whole UICollectionView while the images are loading - presumably as it initiates a large number of simultaneous downloads. Restarting the app causes some, but not all, of the images to be shown.
Looking in the Caches/Pictures.MvvmCross folder I see there are a number of files with .tmp extensions and some without .tmp extensions but a 0 byte file size. I presume that the .tmp files are the ones that are re-downloaded following an app restart and that an invalid in-memory cache entry is causing them not to be re-downloaded until this happens.
I have implemented my versions of MvxDownloadRequest and MvxHttpFileDownloader and registered my IMvxHttpFileDownloader. The only modification in MvxHttpFileDownloader is to use my MvxDownloadRequest instead of the standard Mvx one.
As far as I can see, there are no exceptions being thrown in MvxDownloadRequest.Start or MvxDownloadRequest.ProcessResponse and MvxDownloadRequest.FileDownloadFailed is not being called. Having replaced MvxDownloadRequest.Start with the following, all images are always downloaded and displayed successfully:
try
{
ThreadPool.QueueUserWorkItem((state) => {
try
{
var fileService = this.GetService<IMvxSimpleFileStoreService>();
var tempFilePath = DownloadPath + ".tmp";
var imageData = NSData.FromUrl(NSUrl.FromString(Url));
var image = UIImage.LoadFromData(imageData);
NSError nsError;
image.AsPNG().Save(tempFilePath, true, out nsError);
fileService.TryMove(tempFilePath, DownloadPath, true);
}
catch (Exception exception)
{
FireDownloadFailed(exception);
return;
}
FireDownloadComplete();
});
}
catch (Exception e)
{
FireDownloadFailed(e);
}
So, what could be causing the problems with the standard WebRequest which is not affecting the above version? I'm guessing it's something to with GC and will do further debugging when I get time, but this won't be fore a while unfortunately. Would be very much appreciated if someone can answer this or provide pointers for when I do look at it.
Thanks,
J
From the description of your investigations so far, it sounds like you have isolated the problem down to the level that httpwebrequest sometimes fails, but that the NSData methods are 100% reliable.
If this is the case, then it would suggest that the problem is somewhere in the xamarin.ios network stack or in the use of it.
It might be worth checking the xamarin bugzilla repository and also asking their support team if they are aware of any issues in this area. I believe they did make some announcements about changes to the iOS networking at evolve - see the CFNetworkHandler part late in the video and slides at http://xamarin.com/evolve/2013#session-b3mx6e6rmb - and there are worrying questions on here like iPhone app gets into a state where network requests never complete
Beyond that, I'd guess the first step in any debugging would be to isolate the issue in a simple test app - eg a simple app which just downloads one image at a time and which demonstrates a simple pass/fail for each technique. If you can replicate the issue in a small test app, then it'll be much quicker to work out what the issue is.

HTML5 Offline / Online App

Im building a small todo app in html5. Works fine so far but i have a problem: If the user visits http://www.mydomain.com/ he is prompted to login. If he is logged in on / a different template is served -> my main application template. Plus a cookie is set for session handling.
Now he can add/delete/edit his todos. While he is online the todos are saved on the server.
I also added a cache manifest for my site and use local storage to save his todos when he's offline. This works fine so far.
My Problem: If the user is online and logs himself out of the site, and the server isn't serving the main application template anymore, the browser uses the offline version of the site. But he should only use it if the browser is offline, not when the server is sending another template on the same path.
Someone a hint for me? Thanks in advance!
Use this function to get the cookie that is stored on your client machine. In case it returns null then that means the user is logged out. This should be done every time the page is loaded. You could also redirect the user to the login page.
var function getCookie(c_name)
{
var i,x,y,ARRcookies=document.cookie.split(";");
for (i=0;i<ARRcookies.length;i++)
{
x=ARRcookies[i].substr(0,ARRcookies[i].indexOf("="));
y=ARRcookies[i].substr(ARRcookies[i].indexOf("=")+1);
x=x.replace(/^\s+|\s+$/g,"");
if (x==c_name)
{
return unescape(y);
}
}
}
var cookie = getCookie("myDomainAuthenticationCookie");
if(cookie == null)
{
window.location.href = "/myDomain.com/Accounts/Login"
}