Question

A site I’m working on takes table data, counts that table data and uses a standard loop to display it. Here’s some of the code:

<?php
  $output='';   
  $count=count($deal_datas);
  $face_value="";
  $deal_price="";
  //var_dump(400*20/100);
  $save_value='';       
  $save_value_present='';   
  $category_name='';    
  $cat_ids=array();
  $deal_link='';
  $address_array=array();
  $address='';
  $website_name=''; 
  $website_data=array();

  if($count!=0) {
    for($i=0;$i<$count;$i++) {
      $website_data=get_single_row("web_sites",array("id"=>$deal_datas[$i]->site_id));

      if(count($website_data)!=0) {
        $website_name=$website_data[0]->name;
      }

      $address_array=array();
      $cat_ids=explode(",",$deal_datas[$i]->sub_category_ids);

      if(count($cat_ids)!=0) {
        $where_class=array("id"=>$cat_ids[0]);
        $category_names=get_single_row("sub_category",$where_class);

        if(count($category_names)!=0) {
          $category_name=$category_names[0]->name;
        } else {
          $category_name="All";
        }
      } else {
        $category_name="All";
      }

      $face_value=str_replace("USD","",$deal_datas[$i]->deal_face_value);
      $face_value=str_replace("$","",$face_value);
      $face_value=(int)str_replace(",","",$face_value);
      $save_value_present=(int)str_replace("%","",$deal_datas[$i]->deal_save_percent);

      if($deal_datas[$i]->deal_price!="") {
        $deal_price=str_replace("USD","",$deal_datas[$i]->deal_price);
        $deal_price=(int)str_replace("$","",$deal_price);
        $save_value=$deal_price;
      } else {
        $save_value=$face_value*$save_value_present/100;
      }

      $time_zone_utc=$deal_datas[$i]->deal_oe_end_date;
      $end_date=$time_zone_utc;

      if($website_name!="kgbdeals") {
        $deal_link=base_url()."deals/iframe/".$deal_datas[$i]->slug;
      } else {
        $deal_link=$deal_datas[$i]->deal_link;
      }

      if($deal_datas[$i]->deal_address==0 or $deal_datas[$i]->deal_zip_code==0) {
        $deal_datas[$i]->deal_address="";
        $deal_datas[$i]->deal_zip_code="";
      }

      if($deal_datas[$i]->deal_zip_code!="") {
        $address_array[]=$deal_datas[$i]->deal_zip_code;
  }

      if($deal_datas[$i]->deal_address!="") {
        $address_array[]=$deal_datas[$i]->deal_address;
      }

      $address=implode(" ",$address_array);

      if($deal_datas[$i]->deal_city!="") {
        if(empty($address_array)) {
          $address.=$deal_datas[$i]->deal_city;
        } else {    
          $address.=" - ".$deal_datas[$i]->deal_city;   
        }

        //Check for valid image
        $deal_image=base_url().'uploads/deals/'.$deal_datas[$i]->slug.'.jpg';


        if(getimagesize($deal_image)) {
          $valid_image=1;
        } else {
          $valid_image=0;
        }

        if($i%2==0) {
          $output.='<div class="clsDeal_Whole_Cont clearfix">

Then it outputs the tabled list of data, etc.
Problem is, sometimes that data is sometimes 120 entries that are placed on the screen and the load takes ages.

What I want to do display the data 4 or 8 entries at a time. Then, as the user scrolls, add more in.

Alternatively – to load 4. Display them. Then load 4 more, display them. And so on, so that way the user actually gets to view the contents rather than waiting for the whole list (if this is simpler). Is that possible?

I’m not using jquery for this, though I know I would need to for the whole scroll down bit. So, would there be a way to rewrite the above php in order to display chunks of 4 until the final result is reached?

Answer 1

You have several problems here, beginning with how you ask the question. Be sure to include all the relevant code. You have a truncated code listing that doesn’t deal with the problem at hand; how to break up a long set of data into a human readable format. You do not describe how you’re getting your initial data $deals_data. The implementation details of how your format your output is not relevant to this question. Further, your code is a bit of the mess and doesn’t follow the Single Responsibility Principle.

You should put your data selection and display functionality into single functions:

//returns n through z rows of data. If '0' is provided for finish, returns all rows
function getData($start=0, $finish=0 {
  $data = array();
  if ($finish == 0) {
    //get all data
  } else {
    //get limited amount of data
  }
  return $data;      
}

//returns first $limit rows of data as an html-encoded output string
function displayDeals($deal_data, $limit) {
  ...
}

That function should call a separate function for each of your rows:

//Returns a string of html-encoded data for one row
function displayRow($row_data) {
  ...
}

This displayRow function will be called $limit number of times by displayDeals. Once you get that working, it becomes much simpler to use AJAX for infinite scrolling. You simply create a php function:

function getMoreRows($start, $numberOfRows) {
  $data = getData($start, $start+$numberOfRows);
  $output = displayDeals($data, $numberOfRows);
  return $ouput;
}

This will return that output to the AJAX function that called the php code. Because it’s encoded as HTML you simply replace whatever available div with that new string.

Note that JQuery will make this AJAX easy, but you will need some javascript in order to make this functional, or suffer a long round-trip call to a new php page each time. The latter is easy, but avoids making the user interface smooth and lazy-loaded like you want. Here is how:

$.ajax({ url: '/my/site',
         data: {action: 'getMoreData'},
         type: 'post',
         success: function(output) {
                      //replace your div with new data
                  }
});

On the server side you need a php page to handle the request:

if(isset($_POST['action']) && !empty($_POST['action'])) {
    $action = $_POST['action'];
    switch($action) {
        case 'getMoreData' : getMoreRows($_POST['lastDataIndex'], $_POST['numberOfRowsToFetch']);break;
        // ...etc...
    }
}

As a minor post-script about style: you should be cautious about mixing if and if-else styles, in regards to brackets. Generally, you want you code to be tight and quickly readable, and you want to never be in doubt if code is in a block. Personally, I always use brackets with if and if-else, but you should avoid using brackets in your if statement and not in your else case at the very least. Keep an eye on human readability, or you will find that you’ll be frustrated by random bugs that arise because you assume a thing is or is not in a block when it’s the opposite case.