使用php获取网页XML代码并在其上使用XPATH

Question

Maybe its a question answered before but im so noobie in Web Development. Im trying to get a full XML text from this page:

Human Genome

And, I need to do some XPath queries in that code, like "get the ID" and others. For example:

//eSearchResult/IdList/Id/node()

How I can to get the full XML in a php object to request data throught XPath queries?

I used this code before:

<?php
$text = $_REQUEST['text'];
$xmlId = simplexml_load_file('https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi?db=gene&amp;term='.$text.'%5bGene%20Name%5d+AND+%22Homo%20sapiens%22%5bOrganism');
$id = $xmlId->IdList[0]->Id;
$xmlGeneralData = simplexml_load_file('https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esummary.fcgi?db=gene&amp;id='.$id.'&amp;retmode=xml');
$geneName = $xmlGeneralData->DocumentSummarySet->DocumentSummary[0]->Name;
$geneDesc = $xmlGeneralData->DocumentSummarySet->DocumentSummary[0]->Description;
$geneChromosome = $xmlGeneralData->DocumentSummarySet->DocumentSummary[0]->Chromosome;
echo "Id: ".$id."
";
echo "Name: ".$geneName."
";
echo "Description: ".$geneDesc."
";
echo "Chromosome: ".$geneChromosome."
";?>

But, according with the profesor, this code doesn't use Xpath queries and is required that the page use it.

Someone can help me or explain me how to do it?

Answer 1

Here's converted code to Xpath query.

<?php

$text = $_REQUEST['text'];
$xmlId = 'https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi?db=gene&amp;term='.$text.'%5bGene%20Name%5d+AND+%22Homo%20sapiens%22%5bOrganism';

//Load XML and define Xpath
$xml_id = new DOMDocument();
$xml_id->load($xmlId);
$xpath = new DOMXPath($xml_id);

//Xpath query to get ID
$elements = $xpath->query("//eSearchResult/IdList/Id");

//Loop through result of xpath query and store in array of ID
if ($elements->length >0) {
    foreach ($elements as $entry) {
        $id[] = $entry->nodeValue;
    }
}

echo "Id: ".$id[0]."
";

//Output the first string of ID array from xpath result set
$xmlGeneralData = 'https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esummary.fcgi?db=gene&amp;id='.$id[0].'&amp;retmode=xml';

//Load XML and define Xpath
$xml_gd = new DOMDocument();
$xml_gd->load($xmlGeneralData);
$xpath = new DOMXPath($xml_gd);

//Xpath query to search for Document Summary with first string of ID array from previous result set
$elements = $xpath->query("//eSummaryResult/DocumentSummarySet/DocumentSummary[@uid='".$id[0]."']");

//Loop through result of xpath query and find nodes and print out the result
if ($elements->length >0) {
    foreach ($elements as $entry) {
        echo "Name: ".$entry->getElementsByTagName('Name')->item(0)->nodeValue."
";
        echo "Description: ".$entry->getElementsByTagName('Description')->item(0)->nodeValue."
";
        echo "Chromosome: ".$entry->getElementsByTagName('Chromosome')->item(0)->nodeValue."
";
    }
}

?>