Extracting Data from .osm XML file With Php

Question

I tried to extract some data from an .Osm File.

So I have something like this:

<way id="28747493" visible="true" version="7" changeset="9347177" timestamp="2011-09-19T21:48:11Z" user="Camilo Alvarez" uid="492132">
  <nd ref="316077528"/>
  <nd ref="316077503"/>
  <tag k="highway" v="primary"/>
  <tag k="lanes" v="1"/>
  <tag k="name" v="Calle 51"/>
  <tag k="oneway" v="yes"/>
  <tag k="ref" v="Boyacá"/>
 </way>
<way id="28747492" visible="true" version="9" changeset="7227086" timestamp="2011-02-08T15:33:22Z" user="dmartinh" uid="314700">
  <nd ref="358031212"/>
  <nd ref="316077505"/>
  <tag k="foot" v="permissive"/>
  <tag k="highway" v="footway"/>
  <tag k="name" v="Calle 52"/>
 </way>

So, I want to extract every single "ref" and put into a table called "referencia and I want to assign tag name "calle 51" to that ref values.

Something like this:

Table referencia

idnode -------- via

316077528 |  Calle 51 |
316077503 |  Calle 51 |
358031212 |  Calle 52 |
316077505 |  Calle 52 |
----------------------

So, I can store "idnode" values very well but I can't store the "via" values. I tried to make some kind of foreach without sucess.

And definitely I don't know why is suposse we have one Iteration that get "idnode" values and "via" why is not possible to store together.

<?php < ? global $referencia;
global $via;
/*
/**
* OSM Overpass API with PHP SimpleXML / XPath
*
* PHP Version: 5.4 - Can be back-ported to 5.3 by using 5.3 Array-Syntax (not PHP 5.4's square brackets)
*/

$dbhost = 'localhost';
$dbuser = 'root';
$dbpass = '';
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
mysql_select_db('map');

if (!$conn)
    {
    die('Could not connect: ' . mysql_error());
    }

echo 'Connected successfully';

$xml = simplexml_load_file("map.osm");
$counter = - 1;

foreach($xml->children() AS $child)
    {
    $counter++;
    if ($child->getName() == 'way')
        {

        // if($child->getName() == 'node'){
        // echo $counter;

        $name = "";
        $id = "";
        $lat = "";
        $lon = "";
        $name = $child['version'];
        $id = $child['id'];
        $lat = $child['lat'];
        $lon = $child['lon'];

        }

    foreach($child->children() AS $grandchild)
        {
        if ($grandchild->getname() == 'nd')
            {
            $referencia = $grandchild['ref'];

            if ($grandchild->getName() == 'tag')
                {
                if ($grandchild['k'] == 'name')
                    {
                    $via = $grandchild['v'];
                    }
                }

            mysql_query("INSERT INTO referencia (idnode,via) VALUES ('$referencia','$via')");
            }
        }
    }




?>

Thanks in Advance.

Answer 1

You can use SimpleXMLElement::xpath to get both "via" and the corresponding "idnode" values. For example :

$raw = <<<EOF
<root>
    <way id="28747493" visible="true" version="7" changeset="9347177" timestamp="2011-09-19T21:48:11Z" user="Camilo Alvarez" uid="492132">
      <nd ref="316077528"/>
      <nd ref="316077503"/>
      <tag k="highway" v="primary"/>
      <tag k="lanes" v="1"/>
      <tag k="name" v="Calle 51"/>
      <tag k="oneway" v="yes"/>
      <tag k="ref" v="Boyacá"/>
     </way>
    <way id="28747492" visible="true" version="9" changeset="7227086" timestamp="2011-02-08T15:33:22Z" user="dmartinh" uid="314700">
      <nd ref="358031212"/>
      <nd ref="316077505"/>
      <tag k="foot" v="permissive"/>
      <tag k="highway" v="footway"/>
      <tag k="name" v="Calle 52"/>
     </way>
</root>
EOF;
$xml = simplexml_load_string($raw);

foreach($xml->xpath("//way") AS $way){
    $via = $way->xpath("tag[@k='name']/@v")[0];
    foreach($way->nd AS $nd){
        $idnode = $nd["ref"];
        echo $idnode .", ". $via  ."<br>";
    }
}

Demo

output :

316077528, Calle 51
316077503, Calle 51
358031212, Calle 52
316077505, Calle 52

xpath explanation :

• //way selects all <way> elements anywhere in the XML document.

• tag[@k='name'] selects <tag> child of current context node having k attribute value equal name. Then from that <tag>, /@v returns v attribute.