I am using CodeIgniter. In my controller I am decoding a JSON response and simply displaying the values upon loading a view. I am simply displaying all my content from a JSON array (no database used). It is completely an array from which i am rendering the data.I want to autoload the content whilst scrolling.
Example:
$resultjson = $this->curl->simple_get("http://www.test.com/api/records.php?ak=XXXXXXXX&ts=XXXXXXXX&sig=XXXXXXXX&postano=XXXXXX&count=100");
How can I fetch 10 records when autoloaded? Just like the http://pinterest.com/ mechanism. How can I achieve this?
Are there any plugins? Does CodeIgniter already have a solution for it such that I can use classes or libraries?
You can use the jQuery scroll event, scrollTop() and the $.ajax();
Basicly catch the scroll event, see if $(window).scrollTop() is higher than <div id="auto_load"></div> (through .offset()) and run ajax once if that's the case.
div#auto_load would be places bellow loaded content, and will "jump" down once content is added.
Example:
var ajax_once = false;
$(window).bind('scroll', function() {
if (ajax_once)
return;
if ($(this).scrollTop() >= $('div#auto_load').offset().top) {
ajax_once = true;
$.ajax({
/* Url, dataType json etc. */
}).done(function(data) {
/* use the data */
ajax_once = false;
});
}
});
Codeigniter is a php framework which means server side therefore no client side logic built in.
You can use a jQuery plugin for that called infinite scroll. Here is the link to it: http://www.infinite-scroll.com/
Related
I am looking to display the total number of files in a database. To clarify, say I had a website where people could upload pictures of their cars, and I wanted to display a live number of how many pictures there are, what would be the best way to do this? Javascript, php? A mix? I envision a div with a number saying "Total Pictures: x" and where x would be whatever the live total is. I plan on using MySQL to store all the data on the website. Is this even recommended to have something communicate with the server this much? Is there a name for displaying a live number? Thanks!
If you are thinking to use the AngularJS way, you could create a Poller service which polls every second (assuming your /counter.php returns json):
app.factory('Poller', function($http, $timeout) {
var data = { response: {}};
var poller = function() {
$http.get('/counter.php').then(function(r) {
data.response = r.data;
$timeout(poller, 1000);
});
};
poller();
return {
data: data
};
});
Then your controller:
app.controller('CounterCtrl', function(Poller, $scope){
$scope.counter = Poller.data;
});
And finally in your view:
{{counter.response}}
You can read more about $http
Set up a PHP script that queries the database and returns the total file upload count. After that, you can use JavaScript on the page to periodically call the server in a specified interval of time and fetch the count data from your PHP script. Using jQuery and GET, you can do something like this:
jQuery(function($){
setInterval(function(){
$.get( '/counter.php', function(fileUploadCount){
$('#counter').html( fileUploadCount );
});
},20000); // 20 seconds
});
In your HTML:
<p><span id='counter'>xx</span> files have been uploaded so far!</p>
Hope this helps!
How live do you want it to be? Just whenever someone updates the site it's going to have the new value or do you actually want it to update in near real-time?
If it's the latter you have to use Javascript against some kind of API that returns the amount of files in the database. I can't help you with that bit since you are using PHP, but it shouldn't be too hard. Just return some JSON looking something like
{ fileCount: 45020 }
Client-side you have a few options. You have the different javascript frameworks like AngularJS and EmberJS (and many more), as well as just 'plain old' javascript and frameworks like jQuery
The keyword is really AJAX, even if that is just a sort of buzzword for using javascript to make websites dynamic.
I am a fan of using AngularJS because it's easy, but I'll try to give you some pointers for using jQuery first. Note that I have not used jQuery in years now.
The jQuery way
jQuery has a function called jQuery.getJSON(), and according to the documentation you can use that function something like this:
// Assign handlers immediately after making the request,
// and remember the jqxhr object for this request
var jqxhr = $.getJSON( "http://example.com/api/fileCount.json")
.done(function(data) { console.log(data) })
.fail(function() { console.log( "error" ); })
.always(function() { console.log( "complete" ); });
So this means we can call an endpoint and fetch some data using jQuery.
Here is a link to a tutorial about the basics of jQuery by the way.
jQuery makes us able to do things like this:
<div id="divTest1"></div>
<script type="text/javascript">
$("#divTest1").text("Hello, world!");
</script>
When that is executed the div with id "divTest1" will contain the text 'Hello, world!'.
That sounds like something we could use here!
Javascript also has this really nice function called setTimeout(), which allows us to make it call a function later.
This describes how to use jQuery with setTimeout()
As you can see it also shows us jQuery.documentReady(), which is an event that fires when the website is finished loading, so it is a good place to put code we want executed.
The example below shows how to use jQuery to hide a div with id=div after 3 seconds.
jQuery(document).ready(function () {
setTimeout( "jQuery('#div').hide();",3000 ); //hide a div after 3 seconds
});
Combining these things you should be able to make a repeating call that fetches data from your server and then updates a div or another element with the data you have fetched.
Just create a function which uses jQuery.getJSON() to fetch data, and then at the bottom of that add a setTimeout call to run itself in X seconds (however often you want it to update).
In jQuery.documentReady() you call that function the first time the document loads.
And in the .done() bit of the getJSON() call you add the data you got from the server to your div with whatever html you want. I showed you how to use $("#divTest1").text(), but there is also a .html() which acts the same but you should use it to add html to a element.
The angular way would be to use AngularJS's $http to do the same thing, but I wouldn't recommend learning AngularJS until you have a bit of a better grasp on Javascript.
When you do though, I highly recommend it. It's a much better approach than using jQuery.
You can read about AngularJS here
I hope this helps!
I'm developing a web app using Kohana PHP framework and I got stuck. I set a PHP variable in my Controller to use it in a View. I would like to update this variable in the View continuously without refreshing the page. What I'd like to do is show a chart in real time using data from an SQL database where the curves' data is stored in this PHP variable. How can I do this? Is it possible to update this variable directly in the View (using my function in the Model)?
You can create an AJAX request with Javascript to your application without reloading the page. What happens is that the request is made to your controller/action, there you can query your database and you can pass back whatever your like. The AJAX request can retrieve the returning data and do something with it (in our case, replace some content with the new content).
You have to include this Javascript code on your page. In this example I use jQuery to make the AJAX request:
$.ajax({
url: /do/something /* URL of your controller/action */
success: function(data) { /* the data variable will receive the new content from the controller/action */
$('#the_id_of_your_html_tag').html(data); /* replace the html content with the new data */
},
});
In your Kohana controller you have something like this:
class Controller_Do extends Controller_Template
{
public function action_something()
{
$this->auto_render = false;
// make some call to your database, use your model whatever
echo 'some string or variable';
return;
}
}
Your Html of your view will be like this (according to the example):
<div id="the_id_of_your_html_tag">something</div>
In my website I will have a "browse catalogue" button, which, onclick will change several elements of the page to display the catalogue element. I dont want a full page reload because several elements such as the nav bars and news feed will stay the same.
My question is how can i change several different divs with ajax onclick?
Essentially im not sure how to do place several different components in different divs across a page.
And i know there's a limit on simultaneous ajax calls, so im sure the proper way to do it wouldnt be to make a unique ajax call for each of my divs.
A little guidance would be great.
Using jQuery, you can get an json array of elements for each block that needs to be updated:
In your html page:
$.get("page.php?id=42",
function(result){
$('#title').text(result['title']);
$('#description').text(result['description']);
$('#price').text(result['price']);
}, "json");
In page.php:
$result = array('title' => 'foo', 'description' => 'bar', 'price' => 3);
echo json_encode($result);
header('Content-Type: application/json');
die();
I'm not sure if the right decision will be to send several ajax requests. Just create a request with unique attribute value, in so shape that server will know which blocks you need. On server side all required blocks concatenate in json object, and return it to client. After just parse object on blocks that should be. For example
$.ajax({
url : 'http://your.server.doment',
data : 'block[]=1&block[]=7&block[]=15',
type : 'post',
dataType : 'json',
success : function (object){
for( el in object) { $('#block_'+el).html(object[el]); }
}
});
you can use json
example
php request ajax
$div1="<table><tr><td>x</td></tr></table>";
$div2="<table><tr><td>x</td></tr></table>";
$div3="<table><tr><td>x</td></tr></table>";
$json = '{"div1":"'.$div1.'","div2":"'.$div2.'","div3":"'.$div3.'"}';
return $json;
uses jquery
$.ajax({url: 'ajax/test.php',
success: function(data) {
var obj = JSON.parse(data);
$("mydiv1").html(obj.div1);
$("mydiv2").html(obj.div2);
$("mydiv3").html(obj.div3);
}});
if you have a error in the parce function
replace spaces
example
$arr =array("\n","\t");
$div1= str_replace($arr,"",$div1);
Practically, ten or more elements updated in parallel on the page (each by a separate ajax) will not make such a big difference (unless you can test it with your website deployed into productive environment and prove I am wrong).
Nonetheless, if you wish to compact all the data exchange to one single request/response ajax call - it is very well possible but does require certain flexibility on the server side (see http://php.net/manual/en/function.json-encode.php).
I.e. one of the possible solutions is to produce json response on the server side, that generates a key-value pairs (JSON - javascript {} object) with keys being id of your elements and values being (new) html.
There are tons of ajax JS frameworks as jQuery, prototype, dojo, etc. (I will pick jQuery for this one).
Ajax request
$.ajax({
...
})
See http://api.jquery.com/jQuery.ajax/
Server response
// Assume we got
// var data = {key1:'html1',key2: 'html2'};
// Ajax handle can look like
success(data) {
$.each(data, function(key, val){
//console.log(key, val);
// Do some checks here.. But key should indicate #id of html elements
$(key).empty().append(html);
});
}
This is a basic outline but should keep you going into the right direction.
I'm working on a PHP / AJAX application and it's quickly becoming unmanageable!
The application is designed to work much like a a desktop application so almost every user action results in an AJAX call.
For every one of these actions I have some jQuery that posts the data to my PHP script and runs a corresponding PHP function that handles the server side actions.
That means in my jQuery file i'll have something like this:
$('.delete-project').on('click', function(){
// Ajax request to http://myapp.co.uk/ajax/delete_project
});
$('.delete-user').on('click', function(){
// Ajax request to http://myapp.co.uk/ajax/delete_user
});
$('.delete-keyword').on('click', function(){
// Ajax request to http://myapp.co.uk/ajax/delete_keyword
});
I'm sure there is a better way of doing things, but how is it generally done to avoid lots of similar code? The above actions could possible rolled into one 'delete' ajax request which posts the item type and a database ID but a lot of my functions post different data and require different parameters so wouldn't fit so neatly under one jQuery handler.
I've tried finding some resources on how an AJAX application should be put together but all I can find is beginner tutorials on making AJAX requests etc, not how to write a scalable AJAX application.
Just to be clear I know how AJAX works, I'm just trying to find the best way of implementing it in terms of reducing the jQuery and PHP needed where possible.
Are there any good resources that deal with this sort of thing?
You can roll all those into one delete function by using attributes in HTML, for example:
$('.delete').on('click', function(){
var delete = $(this).attr('data-delete');
// Ajax request to http://myapp.co.uk/ajax/delete_{delete}
});
Then your HTML would be something like:
Delete
More information on data-attributes
Not sure if this would help but you could create some functions to reduce your code as it grows. For starters you could prevent duplicating of the ajax call by putting the jQuery .ajax function in a custom wrapper function of your own. For example:
function ajaxGet(myUrl, queryString, successCallback, errorCallback) {
if(queryString) myUrl+= "?" + queryString;
$.ajax({
url: myUrl,
type: "GET",
data: null,
success: function (res) {
if(!successCallback) return;
else successCallback(res);
},
failure: function (res) {
if(!errorCallback) return;
else errorCallback(res);
}
},
By creating a wrapper function, you can pass in the needed data without duplicating the $.ajax call code over and over in each of the click functions. You can also create a similar function for an ajax call using post. You could then dynamically build the click functions to further reduce your code:
function buildClicks() {
setupClick([url], [data], [success], [error], [$(elem)]);
setupClick([url], [data], [success], [error], [$(elem)]);
setupClick([url], [data], [success], [error], [$(elem)]);
}
//Setup clicks for each button or link
function setupClick(url, data, success, error, elem) {
elem.click(function () {
ajaxGet(url, data, success, error);
});
}
In this example I'm assuming your using a "GET" and adding a query string. You could easily adapt this to pass, a JSON formatted object for example, using a custom "POST" function. In that case [data] would be an object not a query string.
Sorry this code isn't the clearest. Let me explain it a little more. The buildClicks function would allow you to setup multiple click events on different elements by passing in the required data. I'm not sure if you are passing any data, but the above functions would allow for it. By dynamically creating the clicks you can avoid duplicating the .click code over and over. Just call the buildClicks function on document ready as such.
$(document).ready(function () { buildClicks(); });
NOTE: The success and error callbacks are functions that will be executed when your call either completes successfully or errors out. If you do not wish to use these they can be ommitted or null can be passed in. Make sure if you do pass in functions that you leave off the "()" on the end of the function name. Otherwise the functions will be executed prior to the success or failure of the ajax call. For example:
ajaxGet("http://testurl.com", null, ajaxSuccess, ajaxFailure);
ajaxSuccess() {
}
ajaxFailure() {
}
You could set an ID attributes to that buttons and a class like submit-button.
Then hang a handler on that $('.submit-button') while using an ID attribute value to define the URL to call, like that:
$('.submit-button').on('click', function(){
$action = $(this).attr('id'); //lets say the ID's value is 'delete_project'
$url = 'http://myapp.co.uk/ajax/' + $action;
// Ajax request to http://myapp.co.uk/ajax/delete_project is done
});
Anyway any web application that tends to be like a desktop one is only a bunch of JS and few HTML with some PHP behind... That is always badly maintanable...
I used [extJs][1] once for this, which led to using only jQuery and their modules while no (or just a minimum of) HTML was needed to write...
Not a copy-and-paste-solution, but maybe you find some more ideas how to build a scalable client-server application when looking for how REST APIs are built. I find REST a very good structure to keep a clear server-side API when building such apps, and i'm sure there are tutorials around how to do the corresponding client-part cleanly too.
In my application I do quite a lot of ajax calls too. I found that the easiest way to do things was to create myself a wrapper for all ajax calls such as:
var MySite = function()
{
AjaxWrapper : function(type,url,data,callback,noloading)
{
$.ajax({
type: type,
url: url,
data: data,
success:function(json)
{
if(json.status === true)
{
if(typeof callback === 'function')
{
callback(json);
} else {
// A generic success handler
}
} else {
// An error handler
}
}
});
};
}();
then you'd call it like:
MySite.AjaxWrapper("GET", "somehref", {}, function(json)
{
// json has the result of your json callback
// you could also make this a separate function
// or not have it
});
this let's you call your ajax on just about anything you want. You could then use something like data attributes, or just the standard href for anything that requires ajax and add an event to all links that pass through this function. Or, if you wanted some to do certain things just make the callback function different for those.
I'm finding this hard to explain, but this is what I've used for a couple of ajax-rich projects and it makes things so much easier!
For an example for your case you could then use something like:
$('a[class|="delete"]').on("click", function()
{
MySite.AjaxWrapper("POST", $(this).attr("href"), {param:number1}, DeleteHandler);
});
The way I would do this would be to have a single function for all actions:
$('.actions').on('click', function (e) {
e.preventDefault();
var action = $(this).data('action'),
id = $(this).data('id');
$.get('/local/handler.php', {
'action': action,
'id': id
}, function () {
// Callback stuff here
});
});
And HTML:
Delete Project
Delete User
Delete Keywork
And the PHP file should have if statements based on the action parameter that performs the requested action.
EDIT:
This way your not limited to just delete actions, so you can scale your app in the future.
Also, If the different actions become a large list (e.g. deletes of many kinds, updates, adding), I would create a separate PHP file for each action and include them in one master file. This will allow for easy scaling.
I have a complicated page being rendered by PHP and would like to keep all elements of the page up to date via AJAX long polling. Is there some kind of general / clever way to design an infrastructure to support this without having to specify manually each element to update? Just looking for ideas. Thanks!
Using jQuery, I would send a comma-separated list of jQuery selectors to update to the server. The server will ultimately respond by reading those selectors and producing the HTML to fill up the elements matching the selectors:
$.get("/updater", { elementsToUpdate: "#someDiv,#someTable,#someOtherElement"}, function(json) {
$.each(json, function(k, v) {
// the key is the selector, the value is the
// HTML to set to that (or those) element(s):
$(k).html(v);
});
}, "json"); // we are expecting the server to return JSON
The server will respond by sending JSON to the client with the following structure:
{"#someDiv":"this is some HTML to fill up div with ID someDiv","#someOtherElement":"here is some more HTML","#someTable":"here is some more HTML"}
maybe add a special class to all the elements to be updated via ajax, and also you can encode extra data in some other attributes for example
<a class="ajaxUpdate" data="{'a':'json or whatever', 'put whatever here':'ok'}">test</a>
then with jquery you can easily pull out that data and eval it, and use it in your ajax
You can poll a page which returns you the json-encoded structure of your page, like:
var page = {
'elem1': {
'html': '<div>... ',
'update': True
},
'elen2': {
'update': False
and so on, then update what necessary, having only one poll.
Keep your pages elements structure as private data and have the public elements to update them
var page = (function(){
var private_data = {
//json
};
return {
workOnData : function(){//process the data}
}
})()
This is good way you can keep your pages data safe and smooth.
I'd use jQuery to do that if I were you o: then you could do something like...
$('div.updateThisClass').css('color','#fff')