Filtering XML results in PHP

[camargo]

Hello fellow PHP Freaks,

 

I'm new here, and this is my very first post! So hello to you all! Here's my situation:

 

I'm in the process of creating a page that displays multiple lines of inventory for a bunch of products (let's call them 'widgets'). The widgets are listed in XML format (they'll end up being pulled from a MySQL DB eventually).

 

<inventory>
   <widget>
      <name>One</name>
      <color>Red</color>
      <weight>5</weight>
      <price>15</price>
   </widget>
   <widget>
      <name>Two</name>
      <color>Blue</color>
      <weight>8</weight>
      <price>21</price>
   </widget>
   <widget>
      <name>Three</name>
      <color>Green</color>
      <weight>3</weight>
      <price>12</price>
   </widget>
   <widget>
      <name>Four</name>
      <color>Red</color>
      <weight>15</weight>
      <price>35</price>
   </widget>
</inventory>

 

Now, I have a PHP page that loads up my XML file using SimpleXML:

 

<?php 
$xml =  simplexml_load_file('inventory.xml');
?> 

 

Then it will display information for each widget in a nice, neat format:

 

<?php
foreach ($xml->widget as $widget) {
    echo "<div class='widget'>";
    echo "<span class='name'>" . $widget->name . "</span>";
    echo "<span class='color'>" . $widget->color . "</span>";
    echo "<span class='weight'>" . $widget->weight . "</span>";
    echo "<span class='price'>" . $widget->price . "</span>";
    echo "</div>";
}
?> 

 

My question to you is, how would I go about building a function that would filter the results to this page. For instance if there was a set of check-boxes that allowed you to only display the "Red" or "Blue" colored widgets. Or perhaps I only want to see "Red" widgets with a price below "20".

 

Any help or pointers are completely appreciated. Thanks in advance!

[Barand]

Something like

<?php
$str = '<inventory>
   <widget>
      <name>One</name>
      <color>Red</color>
      <weight>5</weight>
      <price>15</price>
   </widget>
   <widget>
      <name>Two</name>
      <color>Blue</color>
      <weight>8</weight>
      <price>21</price>
   </widget>
   <widget>
      <name>Three</name>
      <color>Green</color>
      <weight>3</weight>
      <price>12</price>
   </widget>
   <widget>
      <name>Four</name>
      <color>Red</color>
      <weight>15</weight>
      <price>35</price>
   </widget>
</inventory>';

function xmlfilter ($x, $color, $weight, $maxprice)
{
    $xml = simplexml_load_string($x);
    $res = array();
    foreach ($xml->widget as $w)
    {
        $keep = 1;
        if ($color!='')
        {
            if ((string)$w->color != $color) $keep = 0;
        }
        if ($weight)
        {
            if ((int)$w->weight > $weight) $keep = 0;
        }
        if ($price)
        {
            if ((int)$w->price > $maxprice) $keep = 0;
        }
        if ($keep) $res[] = $w;
    }
    return $res;
}
$filtered = xmlfilter($str,'Red','',20);
echo '<pre>', print_r($filtered, true), '</pre>';
?>

[camargo]

Hi Barand,

 

Thanks for your quick response. As I look through the code you've written though, I seem to be clueless as to the execution of it. Perhaps I'm less advanced than I made myself out to be. I'm also having a hard time understanding the logic in the function. I'd hate to have you spell it out for me, but I think, in this case... I might need it.

[Barand]

Loop through the widgets.

 

for each widget, assume we keep it ($keep=1)

 

Now check if we are filtering by color (if $color != '' then we are)

If it's not the color we want then set keep to 0

 

Similarly with the other attributes.

 

If $keep is still 1 after the checks, add the widget to the results array

[camargo]

Okay, I'm understanding the logic behind the function. Now how do I get the arguments from a form on the page? I see that the arguments here are already populated. I'm just not familiar with the process of taking a form's values and having PHP use them as arguments.

[Barand]

<?php

$str = '<inventory>
   <widget>
      <name>One</name>
      <color>Red</color>
      <weight>5</weight>
      <price>15</price>
   </widget>
   <widget>
      <name>Two</name>
      <color>Blue</color>
      <weight>8</weight>
      <price>21</price>
   </widget>
   <widget>
      <name>Three</name>
      <color>Green</color>
      <weight>3</weight>
      <price>12</price>
   </widget>
   <widget>
      <name>Four</name>
      <color>Red</color>
      <weight>15</weight>
      <price>35</price>
   </widget>
</inventory>';

function xmlfilter ($x, $color, $weight, $maxprice)
{
    $xml = simplexml_load_string($x);
    $res = array();
    foreach ($xml->widget as $w)
    {
        $keep = 1;
        if ($color!='')
        {
            if ((string)$w->color != $color) $keep = 0;
        }
        if ($weight)
        {
            if ((int)$w->weight > $weight) $keep = 0;
        }
        if ($maxprice)
        {
            if ((int)$w->price > $maxprice) $keep = 0;
        }
        if ($keep) $res[] = $w;
    }
    return $res;
}

if (isset($_GET['sub']))
{
    $color = isset($_GET['color'])? $_GET['color'] : '';
    $weight = $_GET['weight'];
    $price = $_GET['price'];

    $filtered = xmlfilter($str,$color, $weight, $price);
    echo '<pre>', print_r($filtered, true), '</pre>';
}

?>
<form>
Select color <input type="radio" name="color" value="Red"> Red
          <input type="radio" name="color" value="Green"> Green
          <input type="radio" name="color" value="Blue"> Blue
          <br/>
Max weight <input type="text" name="weight" size="5"><br/>
Max Price  <input type="text" name="price" size="5"><br/>
<input type="submit" name="sub" value="Submit">
</form>

[camargo]

I see! Barand you are extremely helpful! Now at the top of that script, you're defining $str as the full content of the XML file. What if I was to do:

 

$str = simplexml_load_file('inventory.xml');

 

Will this achieve the same effect?

[Barand]

Alter slightly to read file

<?php

function xmlfilter ($xml, $color, $weight, $maxprice)
{
    $res = array();
    foreach ($xml->widget as $w)
    {
        $keep = 1;
        if ($color!='')
        {
            if ((string)$w->color != $color) $keep = 0;
        }
        if ($weight)
        {
            if ((int)$w->weight > $weight) $keep = 0;
        }
        if ($maxprice)
        {
            if ((int)$w->price > $maxprice) $keep = 0;
        }
        if ($keep) $res[] = $w;
    }
    return $res;
}

if (isset($_GET['sub']))
{
    $color = isset($_GET['color'])? $_GET['color'] : '';
    $weight = $_GET['weight'];
    $price = $_GET['price'];

    $xml = simplexml_load_file('inventory.xml');               // read xml file
    $filtered = xmlfilter($xml ,$color, $weight, $price);      // pass xml
    echo '<pre>', print_r($filtered, true), '</pre>';
}

?>
<form>
Select color <input type="radio" name="color" value="Red"> Red
          <input type="radio" name="color" value="Green"> Green
          <input type="radio" name="color" value="Blue"> Blue
          <br/>
Max weight <input type="text" name="weight" size="5"><br/>
Max Price  <input type="text" name="price" size="5"><br/>
<input type="submit" name="sub" value="Submit">
</form>

[camargo]

Okay, so I'm 90% there. I've got all my variables setup and I can see how the form functions with the PHP. I've even been able to add filters of my own. But how do I get the data out of the filtered array without using print_r?

 

For instance, before I was able to do the following:

 

<?php
foreach ($xml->widget as $widget) {
    echo "<div class='widget'>";
    echo "<span class='name'>" . $widget->name . "</span>";
    echo "<span class='color'>" . $widget->color . "</span>";
    echo "<span class='weight'>" . $widget->weight . "</span>";
    echo "<span class='price'>" . $widget->price . "</span>";
    echo "</div>";
}
?> 

[Barand]

replace the print_r bit with

    foreach ($filtered as $widget) {
        echo "<div class='widget'>";
        echo "<span class='name'>" . $widget->name . "</span>";
        echo "<span class='color'>" . $widget->color . "</span>";
        echo "<span class='weight'>" . $widget->weight . "</span>";
        echo "<span class='price'>" . $widget->price . "</span>";
        echo "</div>";
    }    

[camargo]

Wow, okay. I was closer than I thought there! Thanks!

 

Now then, is there any way to perform this function without actually refreshing the page. Perhaps using XMLHttpRequest (AJAX)?

[Barand]

See my sig

[camargo]

Hey Barand! Let me show you what I was able to decypher. It ain't working yet, but perhaps you'll be able to tell me why.

 

I've gone ahead and written up a JS file:

 

var xmlHttp

function updateColor(str)
{ 
xmlHttp=GetXmlHttpObject()
if (xmlHttp==null)
{
alert ("Browser does not support HTTP Request")
return
} 
var url="ajaxFilter.php"
url=url+"?color="+str
xmlHttp.onreadystatechange=stateChanged 
xmlHttp.open("GET",url,true)
xmlHttp.send(null)
}

function stateChanged() 
{ 
if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
{ 
document.getElementById("results").innerHTML=xmlHttp.responseText 
} 
}

function GetXmlHttpObject()
{
var xmlHttp=null;

try
{
// Firefox, Opera 8.0+, Safari
xmlHttp=new XMLHttpRequest();
}
catch (e)
{
// Internet Explorer
try
  {
  xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
  }
catch (e)
  {
  xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
}
return xmlHttp;
}

 

Here's is the form that now calls the function when it changes (only focusing on color for now)...

 

<form>
Select color <select name="color" onchange="updateColor(this.value)">
                 <option value="red">Red</option>
                 <option value="blue">Blue</option>
                 <option value="green">Green</option>
                 </select>
</form>

<div id="results">
</div>

 

Plus you can see the new <div> above which has been added to receive the results of the request. And finally the PHP script:

 

<?php
$xml = simplexml_load_file('inventory.xml');

function xmlfilter ($xml, $color)
{
    $res = array();
    foreach ($xml->widget as $w)
    {
        $keep = 1;
        if ($color!='')
        {
            if ((string)$w->color != $color) $keep = 0;
        }
        if ($keep) $res[] = $v;
    }
    return $res;

$color = isset($_GET['color'])? $_GET['color'] : '';

    $filtered = xmlfilter($xml ,$color);
    foreach ($filtered as $widget) {
        echo "<div class='widget'>";
        echo "<span class='name'>" . $widget->name . "</span>";
        echo "<span class='color'>" . $widget->color . "</span>";
        echo "<span class='weight'>" . $widget->weight . "</span>";
        echo "<span class='price'>" . $widget->price . "</span>";
        echo "</div>";
}
}

?>

 

However, I no longer get any results from the PHP code. Did I hack it to pieces or remove something I shouldn't have?

[Barand]

Where do you update the div.innerHTML?

[camargo]

Its located in the JS file under function stateChanged():

 

var xmlHttp

function updateColor(str)
{ 
xmlHttp=GetXmlHttpObject()
if (xmlHttp==null)
{
alert ("Browser does not support HTTP Request")
return
} 
var url="ajaxFilter.php"
url=url+"?color="+str
xmlHttp.onreadystatechange=stateChanged 
xmlHttp.open("GET",url,true)
xmlHttp.send(null)
}

function stateChanged() 
{ 
if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
{ 
document.getElementById("results").innerHTML=xmlHttp.responseText 
} 
}

function GetXmlHttpObject()
{
var xmlHttp=null;

try
{
// Firefox, Opera 8.0+, Safari
xmlHttp=new XMLHttpRequest();
}
catch (e)
{
// Internet Explorer
try
  {
  xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
  }
catch (e)
  {
  xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
}
return xmlHttp;
}

[camargo]

I think something may be wrong with the PHP file, however. If I go directly to it and inject the string myself (ex: ajaxFilter.php?color=red), it won't actually display anything.

[Barand]

this code needs to be outside the function

 

$filtered = xmlfilter($xml ,$color);          // <------------- calls the function xmlfilter
    foreach ($filtered as $widget) {
        echo "<div class='widget'>";
        echo "<span class='name'>" . $widget->name . "</span>";
        echo "<span class='color'>" . $widget->color . "</span>";
        echo "<span class='weight'>" . $widget->weight . "</span>";
        echo "<span class='price'>" . $widget->price . "</span>";
        echo "</div>";
}

[Barand]

Also the line that gets the GET data needs to be outside too

[camargo]

Hah! I just caught that.