I want to update my PHP GUI view when my data source is updated(data source can be a database). I'm having a hard time understanding how I can do this without reloading the whole view for the user.
What I try to achieve is:
Users view are shown, from an handheld device call a script on the site and the script updates a data source, when data source is updated, update the users view with this updated data without reloading.
Is this possible with PHP/JS and how would I achieve this? I do not need any code but more step by step explanation and perhaps what technology to use.
Appreciate any suggestion that leads me forward with this problem.
Best regards,
Gabriel Paulsson
Use ajax for refreshing data when any event happens. The page will not reload by using ajax. It is very simple to use ajax. Googel, gmail and many other use such ajax. Learn in ten minutes form w3school http://www.w3schools.com/ajax/default.asp
It should be possible to do it just with php, telling the page to update itself at a certain interval.
The way I would do it, is to use javascript with ajax and a timed event. The event fires of an ajax call to the server, the server returns any new information.
If you are new to ajax, you probably want to use a library to make things a bit easier to handle. My personal favourite is prototype.js, although at the moment that seems to be a bit "on the way out" and eg jquery may be a better alternative.
Related
I'm currently only using PHP to take user submissions, put them in a database, and echo them out on a page using SQL to select from a table, such as comments. I need a system that will automatically update comments without refreshing the page like on YouTube. The less the user has to manually update, the better.
I want it to work pretty much exactly how YouTube and Twitter function, where it'll say "x NEW COMMENT(s)" and clicking that updates everything.
My teacher recommended a JQuery function, but I don't have any background in that language so I don't know where to begin looking.
I'm at a complete impasse. I will update this if you guys need additional information to aid in my search.
You are looking for AJAX
You will need a HTML page with jQuery/AJAX that calls another PHP page. In that PHP page you do the DB request and then ideally return the data as JSON so that your frontend part can display it to the user.
As every one says, AJAX is the way. You can find a simple blog I did on it here.
How can i create something similar to the Facebook LIKE hyperlink which allows me to update mysql database without refreshing the page?
In other words , I need this hyperlink to update the database once i click it and display how many likes is stored in DB without page refresh.
Thanks in advace.
In plain simple words, you will need to use AJAX, which will get fired when you click the hyperlink, using JavaScript.
There are these options to use AJAX:-
Use JavaScript own functions to fire AJAX.
Use JavaScript libraries, like jQuery, Prototype, and some more.
By far, jQuery will suit every novice to its best & you can have a look in here for more details on AJAX.
Hope it helps.
in even simpler words than my predecessor;
this is what you have
//html
a href='somewhereOverTheRainbow'>LikeThis...
this is what you should have
//javascript
var likeIt=function(myAnchorElem){
//send info to ajax via Zepto, jQuery, Mootools, Dojo, ExtJS - you name it - or a standalone ajax lib
jQuery.get("somewhere.overtherainbow.com/like.php?url="+myAnchorElem.url);
//prevent the default
return false;
}
//html
a href='somewhereOverTheRainbow' onclick='return likeIt(this)'>LikeThis...
#javascriptWizards; I know, he should use addEventListener instead to then get a real event on which he can call preventDefault and more.
next to the ajax way, you could use json-p, an img or an iframe or even by using websockets. But for simplicity and ease, stick with the ajax way!
in general; making a feature such as the facebook like or google "+1" seams very trivial. The truth is far from it; it is one of the harder things to do in the web! The Frontend for it is easy like cake. But the Backend... wanting your website to scale and demanding/needing normal database respond times will bring you on to your knees
I'd suggest the AJAX approach but just to mention it, the effect could be achieved without AJAX by placing the button in an iframe, this iframe could then follow the the link without the page having to refresh.
http://infrequently.org/07/OSCON/sample_code.pdf
http://webdeveloper.econsultant.com/ajax-demos-examples-code-samples/
Some code sample
Why use AJAX for dynamic web pages when you can do it only with php?
The main reason to bother with AJAX is User Experience (UX).
Now AJAX won't necessarily improve UX in every single instance so in a lot of places sticking with pure PHP is perfectly okay.
But imagine the case where you have a text field on the site and a link to vote on something. Kinda like this site. When you add AJAX your users won't loose the text they entered in the textfield when they decide to vote on the link! How incredibly useful!
So if you care about your user's experience it is a good idea to use AJAX in situations like that.
PHP creates and outputs the Content to the Client Browser as it's a Server-Side Language and that's what it was built for, so on a request your code will access database, files etc. and then output the constructed html/text to the client.
Ajax just gives the User a more Desktop like feel. For example deleting a record and instead of the entire page reloading just letting the one element disappear from say a list and letting the server know that the record is to be deleted. But Remember to let the User know when you are busy sending data to the server (With a progress bar in .gif format for example). As lot's of user feel that if nothing happens on the screen to notify them, that the application is frozen which means they will either reload the page or just try to click the button again.
But you will need to provide some sort of compatibility with browsers that have Javascript disable and thus cannot use your AJAX functions, just something to keep in mind.
AJAX stands for Asynchronus Javascript and XML, meaning that a page can get new data, without having to reload a page.
PHP cannot send data without reloading the whole page. A user has to press a button, to send data.
An example of AJAX is for example google suggestions or the tag suggestions on this website.
Context
I'm working on a project that I'd like to make more dynamic with PHP + AJAX.
I'm using jQuery for the AJAX part because I totally suck in Javascript, and anyway it seems to be worth something.
I reached a point where my application needs to use a form to send a post, and I want to use an ajax call to perform this action. In the page I'd like to send the post, there is also a list of the most recent 15 posts submitted.
First question: Should I just forget about it and use just PHP?
The action
The user writes something in the <textarea></textarea> and clicks on a <a id="myPostSubmit">Submit</a> that is the handler that I'll manage on the jQuery script with something like $("#myPostSubmit").live('click', function() { /* here i make the ajax call */ });. If the post is successfully submitted we are going to do something (I'll talk about it in the next section), either we will alert the user using my showAlert(text) function, that shows a black box for 4 seconds with the text in it.
Second question: Should I manage the click event in any other ways? Should I create a function, such as sendpost(post) and attach it into the HTML onclick="" event?
If the post is successfully sent
I'd open a discussion about 2 options:
We refresh the page [not actually
loading the entire page but making
another ajax call that retrieves the
posts lists and makes disappear the
old one, load the PHP file to
retrieve the new posts (including
the one we just sent), and then make
the post list appear]. Pro: 1) We are sure that what the user is reading after the post list is loaded is the real post sent. So it actually double checks the action. 2) We load also some possible posts sent in the mean while. Cons: 1) We have to create a PHP file that gets the post list template, slicing the template of that page in 2 files. 2) It doesn't really seems that smooth to me.
We just use Javascript to get the post template, add it to the list. Pro: 1) We make it really smooth, without reloading the entire page. 2) We don't need of any PHP file to reload the page. We just use Javascript (jQuery). Cons: 1) How do we get the post html template to add it to the list? 2) How do we get the user (logged) informations without PHP?
Third question: Is it better the 1st or the 2nd solution? Would you provide a even better 3rd solution?
The PHP page
The PHP page that will receive this AJAX call is : ?p=action&a=sendpost. The page require $_POST['myMessage'] to be set and not empty and nothing else. The page itself will get all the user infos from the cookies and will manage to perform the needed query.
The application
It is divided in 3 parts: App, Template, Library. Basically each page of the application has its own .app.php and .tpl.php file.
The .app.php file manages the building
of the basis of the page, using classes
and other stuff from the library. In
our case it retrieves datas from the
database and put them into
variable.
The Template is called at the end of the .app.php file. The .app.php file send to the template the retrieved data and the .tpl.php file outputs them.
The library is used to contain the classes and functions we need in the application file.
Fourth question: Is this a good way of manage my web application?
Edit: What about returning the alert message to the user?
I read about an option, inside $.ajax() that will manage the response on success or in error. The documentation about it is very simple and I didn't get it.
Fifth question: How should I return (from the PHP file) the error
or the success?
First question: Should i just forget about it and use just PHP?
Well, you application will relay on JavaScript if you use ajax, this days i think it just fine ;)
Second question: Should i manage the click event in any other ways? Should i create a function, such as sendpost(post) and attach it into the HTML onclick="" event?
Create a function and bind onclick. Code will be more readable ;)
Third question: Is it better the 1st or the 2nd solution? Would you provide a even better 3rd solution?
My solution: ajax submit the form and on callback insert new comment in to the list or display error message if user can't comment.
Check jQuery serilize() for submitting forms data with ajax.
Fourth question: Is this a good way of manage my web application?
It's just fine ;) When you application get's bigger you will have to redesign it, but don't do it know, do it when current solution becomes to hard to work with.
Read some good book on building MVC framework. And on programming patterns in general.
You seem to be on the right track with everything. There are lot of opinions called "best practices" about how to exactly attach event handlers, how to reload the data on the page and how to organize your application, etc, but I personally would rather build more software instead of worrying about details like that. The details will come to you eventually.
I personally find that updating whole chunks of server-side-rendered HTML on the page is more robust solution, but I have seen people getting excellent results with templates.
What is the best way to refresh the content of a var that is included? For example, I have this code:
<marquee>
<?php
include('note.php');
?>
</marquee>
This is great, as I can show on the page the contents of note.php. Say I change note.php but I don't want users refreshing to see the changes...is there any way to refresh the included file every 3 minutes for example?
To refresh only a portion of a page, you'll have to use some kind of Ajax Request : once the page has been sent to the browser, the server has done it's job, and cannot modify is anymore : the request of fetching a new portion of the page as to come from the browser.
You could do some Ajax requesting "by hand", it's not that hard ; but I'd rather suggest that you take a look at some of the great javascript frameworks that exists out there -- that might be helpful in the future, when adding more functionnalities to your application.
For instance :
With prototype, you can use Ajax.PeriodicalUpdater
Or, with jQuery, you could use something based on $.load
Only by using an ajax like call.. take a look at prototype or jquery for decent JS libraries to help with this..
Unless you just want to put some javascript in to refresh the page every three minutes, you'll need to look into another technology, namely AJAX. As far as I know, PHP can not do this alone.