I built an app for work that keeps track of client medications.
Although of course I did not include any client data when I deployed the app in order to be able to demonstrate it to employers, in the dropdown fields you can still see the initials of the clients.
I'm putting it in maintenance mode in between showing it, and I also added a bunch of fake records so that you can only see the real initials mixed in with other random initials (and again, only under the fields in the automatically generated dropdown menus, not in the actual data saved to the database). Since there's no other information about the clients, I think that's pretty much all I really need to do.
But all of this begs a more programmatic solution: how do I edit the previous values that Flask-WTF remembers so that you cannot see them in the dropdown?
Here is what I mean:
Please let me know what options I have!
Thank you.
I have a search field, which lets the user search books (filters records, which are retrieved with ember-data).
I have found that any access the store from the results computed property within my component (see jsbin) makes the typing into the search field very slow (noticeable on my PC, and terrible on smartphone).
Here is a screenshot of the Timeline pane when typing a search query. The displayed part show that every keypress causes A LOT of layout (the search field seems to rerendered on every keypress). I also provide the exported timeline which you can load into your dev tools as explained here
I have tried to recreate the issue in a jsfiddle, but it seems to work just fine. The difference might be that in the jsbin I am using fixtures, while in my app I retrieve data from a real API.
I don't understand what is causing this behavior. It may be hard to come to any conclusion from the data I can provide, but does anyone have any ideas? Has anyone experienced similar performance issues?
Update 2014-03-01
I should note that the performance hit only happens if the results computed property contains a call to the store. If I replace it with any other thing (like just returning [], or some random async method -- like $.get) it not display this performance hit.
Additionally, I should make it clear (in case you didn't read the code), that the results computed property is not called on every keypress, but only when the search is submitted.
This is not a Ember/Ember-data bug, but apparently a Google Chrome bug.
I have created a new question regarding the issue here
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Closed 11 years ago.
I am currently building a registration page where if the user leaves, I want to pop up a CSS box asking him if he is sure or not. I can accomplish this feat using confirm boxes, but the client says that they are too ugly. I've tried using unload and beforeunload, but both cannot stop the page from being redirected. Using those to events, I return false, so maybe there's a way to cancel other than returning false?
Another solution that I've had was redirecting them to another page that has my popup, but the problem with that is that if they do want to leave the page, and it wasn't a mistake, they lose the page they were originally trying to go to. If I was a user, that would irritate me.
The last solution was real popup window. The only thing I don't like about that is that the main winow will have their destination page while the pop will have my page. In my opinion it looks disjoint. On top of that, I'd be worried about popup blockers.
Just to add to everyones comments. I understand that it is irritating to prevent users from exiting the page, and in my opinion it should not be done. Right now I am using a confirm box at this point. What happens is that it's not actually "preventing" the user from leaving, what the client actually wants to do is make a suggestion if the user is having doubts about registering. If the user is halfway through the registraiton process and leaves for some reason, the client wants to offer the user a free coupon to a seminar (this client is selling seminars) to hopefully persuade the user to register. The client is under the impression that since the user is already on the form, he is thinking of registering, and therefore maybe a seminar of what he is registering for would be the final push to get the user to register. Ideally I don't have to prevent the user from leaving, what would be just as good, and in my opinion better is if I can pause the unload process. Maybe a sleep command? I don't really have to keep the user on the page because either way they will be leaving to go to a different page.
Also, as people have stated, this is a terriable title, so if someone knows a better one, I'd really appreciate it if they could change the title to something no so spammer inviting.
As soon as I saw the words "prevent the user" I started to wail in agony. Never prevent the user, only help them.
If they see your registration page and run off, that's their choice. Pop up a javascript confirm box if they've already filled in some data (because they might be navigating away accidentally) but leave it at that. If they haven't touched the form, leave them alone - they don't want to fill in your form.
Look at other methods of engaging users. If your form is huge and scary, break it into simple manageable chunks or better yet, simplify things so much that the user only gives you data when you need it. For example, you might not need their address until you want to post something to them.
By breaking it into multiple parts you can hook them with a simple form and once they've invested that time, they'll be more likely to continue the process.
But don't harass users. If they don't want to register, pestering them with pop-ups and jaavscript dialogues will just chase them off the site completely.
With that in mind, assuming you're just trying to stop people half-filling-in forms, there are a couple of options to genuinely help people:
Detect if the form has changed and ask them a simple confirm() message.
This is all you can do. A CSS "pop-in" just won't work because you can't control* the window location in the unload event.
*You can put an event listener on all your page's links to fire off something to check the form, but this only helps if the user clicks on one of those links. It won't help if, for example, the user clicks back or closes the window. You could do both CSS and javascript but you end up with a bit of a mess.
Persist the state of the form behind the scenes.
An extension to #1. Instead of squabbling with the user, let them go where they want but save the content of the form either to session or cookie (if it'll fit) and put something on the page (like SO's orange prompt bars at the top of the page) that reminds them that they've started filling in a form and gives them a link back to the form.
When they click that link, you load the data out of the cookie (or session) back into the form and let them carry on. This has the clear benefit of letting them do what they like on your site and keeps the data safe.. ish.
If they don't come back and their cookie/session expire, that's their fault. You can only lead a horse to water. It's not your job to force it to drink.
Don't do it.
But if you want, try this. Record mouse positions and detect a quick upward thrust -- the user is reaching for the BIG X or the top left or top right. Now might be your chance for an unobtrusive box in the screen.
I've seen this implement on the web and it is evil.
If you want to trap links, you could rewrite the links in the page to go to a "you really want to leave?" javascript function, passing the destination URL as an argument.
If you wanna keep users from using their "Back" button, or keep them from putting another URL in the address bar, stop. Stop now. (1) Browsers were made to prevent exactly that kind of obnoxious behavior, and (2) Even if they allowed it, see the last two words of (1). It's freaking rude. Your site is not that special, no matter how cool you think it is.
window.onbeforeunload = function() { return "Message"; };
Use a JavaScript like this to display a leave confirmation message.
Here are just a couple of approaches I could think of but they are not without flaw:
Whatcha Gonna Do technique
Detect the mouse position going towards the edges of the browser as the user might be going to close the tab, window, go back, navigate elsewhere among other things. If so, immediately prompt them that that may be a mistake and they are going to lose out on something very valuable. However, the catch here is that you don't know for sure what their intentions were and you might piss them off with that popup. Also, they might use a bunch of shortcuts such as Ctrl+W etc to do the same.
You've Got Mail technique
If you've managed to get hold of the user's email address before they closed the page, you've hit a jackpot. As soon as the user types anything into the email box and then leaves it, immediately send it to the server using AJAX. Save the state of the page into localStorage or on the server using a cookie or something so it can be recreated later. Every couple of hours send them an email giving them a direct link to the previously saved form, and maybe with special offers this time.
History Repeats Itself technique
Then there's the infamous history manipulation where you keep stacking the current page into the document history so the back button renders effectively worthless.
Don't Put All Your Eggs In One Basket technique
Another technique off the top of my head is to create multiple windows in the background with the registration form and keep them all in sync when any the fields in any one changes. This is a classical technique and really puts the "don't put all your eggs in one basket" saying into real-life usage.
Another advantage of this awesome technique is even if the user closes one of the windows, and later comes across an identical cloned window with all the fields they filled up-to-date populated, they might get confused and think that they never closed the page. And guess what, this time they might just go ahead and fill out the registration form. But you have to be cautious with this as anything more than 2 or 3 clones will make it obvious as to what's going on.
You're Winner technique
Another technique is to tell every user they they are the Xth visitor on the site and use a good rounded number for X such as 1000, 10000, 50000, etc. Tell them that they can claim their prize once they register on the site. Imagine how special each user feels when they land on your site. The prize doesn't have to be anything tangible, it can simply be free coupons that you find on the intertubes.
Where Do You Want To Go Today? technique 1
This is basically a rip-off of your answer. Use document.location.href = 'some url' inside your onbeforeunload callback to navigate to a different page before it is unloaded.
1 Firefox only.
Note: there is no silver bullet solution here unless you write your own browser with your own security policies, but these are all optimizations that you can do to make it utterly impossible for users to leave.
Not all browsers support a modal popup, without which your page would go ahead and navigate anyway.
This is real awful requirement. The sort of requirement that is reasonable in a desktop application but entire unreasonable feature of a web site. Imagine being unable to leave a website.
The answer is either use the horrible confirm box and lump it. Or don't ask the user to enter too much data per page. Use a step by step wizard style data entry, the loss due to accidental navigation is minimised.
You can change the Value of the url using document.location.href = "www.website.com"
I can accomplish this feat using confirm boxes, but the client says that they are too ugly.
If the problem is the ugliness of the standard JS popup boxes, try something like this: http://www.sohtanaka.com/web-design/inline-modal-window-w-css-and-jquery/
Apart from that I second what most people are saying: do this with extreme caution if you don't want to lose users.
I am blocking a huge number of bots, except the ones from search engines, and then only allowing 2seconds of session management.
However, spam bots are still able to by-pass these measure and create a huge number of requests which is 'killing' the server.
I have read other articles on this site but none seem to directly answer this issue.
A bot probably behaves faster than a human. You could time how long it takes them to fill out the form. Anything less than a second or two is a bot.
A bot probably doesn't have JavaScript turned on. You could use that to your advantage.
You could hide a link via css (or not give it any text) that takes the bot to a bot.cfm page, which could then set a session value.
There are some open source projects but I can't remember the names of them off the top of my head.
CF10 has a new validation function.
Ben Nadel has written some useful posts in his blog regarding spiders/bots.
http://www.bennadel.com/blog/1083-ColdFusion-Session-Management-And-Spiders-Bots.htm
http://www.bennadel.com/blog/154-ColdFusion-Session-Management-Revisited-User-vs-Spider-III.htm
For forms, I use <cfimage> to create a captcha image. I have found that stuffing the captcha phrase in a session variable can cause problems (I can't remember what the problems were though). So, I now use <cfencrypt> to include an encrypted phrase in the form itself. The action page decrypts the phrase and compares it to what the user put in the captcha form field.
I've found CFSPAMProtect to be very useful at blocking automated form fillers.
It bases its SPAM/HAM test on an aggregate score of a number metrics including time on page, mouse movement (via JS) as well as the classic hidden form fields that shouldn't be filled in (but are filled in by dumb robots).
You can assign your own weightings and monitor the SPAM catch via email to allow you to tailor things.
It can work on its own or link to some third party SPAM tools such as Akismet.
So far I've found that it's good enough on it's own.
It's a custom tag and easy to implement in existing forms too which is nice.
Give it a go...
Say I have a website that has 100 products. Then this is filtered down to 5 sections containing 20 products each. If you were in one of the sections that contained 20 products (e.g. toys), what would be the optimal method to display only 5 toys per page. At the bottom of the list would be next/previous buttons to show the next/previous set of 5 toys.
A better analogy would be google search. There are millions of results but only ~10 are shown at a given time.
So right now I'm using google app engine (python) and django templates. One way I thought of to remedy this problem would be making all the query results go into a div which could then be modified through javascript to give a similar effect. However, if someone were to click their browser's back button, they wouldn't go where they originally came from.
Thanks in advance. Any help would be useful...I don't know what this technique is called so google hasn't been really useful :(
Edit: based on responses, I found my question was solved here: How to use cursor() for pagination?
Look into query cursors. Thay are made to be serialized and sent to client, to be used in creating "next" and "previous" paging requests.
NOTE: don't use offset on queries. This can be VERY expensive, as it actually fetches (and charges) all entities up to offset+limit position, but returns to application only limit results.
I'm not sure that putting all the results as hidden content in the HTML and manipulating it using JS is a very good idea if you might have a large result set (think about what happened if Google used this approach). There's also the back functionality issue that you've mentioned.
So, as for querying a wanted "results page" each time, I think the Google's GQL Reference might help you, take a look specifically at the LIMIT clause, it can help you create the paging mechanism you're looking for by supplying it with the number of items-per-page you want as "count" and the numbers of items-previously-viewed as "offset" (0 at first call).
As for displaying, I think that the Google Images / Facebook News Feed approach might also be interesting to think about (loading on scroll instead of paging), but that's a matter of your personal choice :)
Hope this helps, good luck!
EDIT: After reading Peter's answer, I found it much more efficient to use cursors for pagination, a good reference is given in his answer.