How to prevent XMLWriter from appending blank line to outputted XML file?

Question

The following code creates an XML file, but the last line is blank which causes problems when validated.

How can I change the following code so that the outputted file does not have a blank line at the end of it?

<?php
$xmlFileName = 'testoutput.xml';

$xml = new XMLWriter;
$xml->openURI($xmlFileName);
$xml->startDocument('1.0', 'UTF-8');
$xml->setIndent(1);

$xml->startElement('name');
$xml->text('jim');
$xml->endElement();

$xml->endDocument();
$xml->flush();      
?>

@DavidRR, the validation problem comes when I validate the XML file with the following code, it tells me that there is "extra content at the end of the document":

$schema = 'test.xsd';
$files[] = 'test1.xml';
$files[] = 'test2.xml';

foreach ($files as $file) {
    validateXml($file, $schema);
}

function validateXml($xmlFile, $xsdFile) {
    $dom = new DOMDocument;
    $dom->load($xmlFile);
    libxml_use_internal_errors(true); // enable user error handling
    echo "Validating <b>$xmlFile</b> with <b>$xsdFile</b>:";
    if ($dom->schemaValidate($xsdFile)) {
        echo '<div style="margin-left:20px">ok</div>';
    } else {
        $errors = libxml_get_errors();
        if (count($errors) > 0) {
            echo '<ul style="color:red">';
            foreach ($errors as $error) {
                //var_dump($error);
                echo '<li>' . $error->message . '</li>';
            }
            echo '</ul>';
        }
        libxml_clear_errors();
        echo '</span>';
        libxml_use_internal_errors(false); // enable user error handling
    }
}

Can you tell us more about the validation problem caused by this blank line? What program is doing the validating? — DavidRR, Sep 04 '12 at 15:54
@Adnan, I'm curious as to why you removed the 'schema' and 'validation' tags that I added. The post does ask about how to suppress a blank line from being written to the end of an XML file. However, the main concern that I see raised by this question is that this blank line is causing an XML schema validation problem. — DavidRR, Sep 06 '12 at 12:38
@Adnan, sorry I didn't intentionally remove any tags, yes, validating the XML file is the main concern, I just remember that having space at the end of an XML file had caused problems for me in the past so would want to solve that problem as well. — Edward Tanguay, Sep 06 '12 at 14:44
Edward, sorry to beat a dead horse... ***I*** was the one who edited your post just to add three more tags to your question: **xml**, **schema** and **validation**. But since I currently have a low reputation, my edit was subject to review, and two of those tags were removed. These additional tags would certainly help others who become engaged in XML validation with PHP find your post. — DavidRR, Sep 06 '12 at 20:27
...and BTW, in my many years of experience validating XML documents, I've never seen whitespace that trails the closing document tag cause a validation problem. This is what intrigues me about your question and leads me to believe there is a bug in the validator... — DavidRR, Sep 06 '12 at 20:33

Gordon · Answer 1 · 2012-09-04T15:59:57.070

I have found no way to change the behavior of XmlWriter in that regard. A possible fix would be to read the file, trim it and then write it back to file, e.g.

file_put_contents($xmlFileName, trim(file_get_contents($xmlFileName)));

demo

An alternative would be to ftruncate the file

ftruncate(fopen($xmlFileName, 'r+'), filesize($xmlFileName) - strlen(PHP_EOL));

demo

The latter assumes there will be a platform dependent newline in the file. If there isn't, this will likely break the file then. The trim version is more solid in that regard as it will not damage the file if there isnt a newline, but it has to read the entire file into memory in order to trim the content.

score 1 · Answer 2 · edited May 23 '17 at 12:12

1

If you are on linux/unix system, you can do:

$test = `head -n -1 < $xmlFileName > $xmlFileName`;

See this.

edited May 23 '17 at 12:12

Community

1
1

answered Sep 04 '12 at 16:05

Prasanth

5,230
2
29
61

score 1 · Accepted Answer · answered Sep 06 '12 at 12:27

Reported problem: Because of the presence of a blank line at the end of an XML file, a schema validation attempt on the file results in the error:

"Extra content at the end of the document"

I'm not able to reproduce your stated problem at codepad, PHP version 5.4-dev, or any of the earlier versions of PHP on that site. I'm including my edited version of your code here as well. (My version includes functions to create the simple XSD and XML files under examination.)

Possibility: Could your problem be related to the version of PHP that you are using?

If I haven't accurately tested your scenario with my adaptation of your code, please further modify my code to precipitate the problem.

<?php

$xsdFile = sys_get_temp_dir() . '/test1.xsd';
$xmlFile = sys_get_temp_dir() . '/test1.xml';

createXsdFile($xsdFile);
createXmlFile($xmlFile);

$files[] = $xmlFile;

foreach ($files as $file) {
    validateXml($file, $xsdFile);
}

function validateXml($xmlFile, $xsdFile) {
    $dom = new DOMDocument;
    $dom->load($xmlFile);

    libxml_use_internal_errors(true); // enable user error handling
    echo "Validating <b>$xmlFile</b> with <b>$xsdFile</b>:";
    if ($dom->schemaValidate($xsdFile)) {
        echo '<div style="margin-left:20px">ok</div>';
    } else {
        $errors = libxml_get_errors();
        if (count($errors) > 0) {
            echo '<ul style="color:red">';
            foreach ($errors as $error) {
                //var_dump($error);
                echo '<li>' . $error->message . '</li>';
            }
            echo '</ul>';
        }
        libxml_clear_errors();
        echo '</span>';
        libxml_use_internal_errors(false); // enable user error handling
    }
}

function createXsdFile($xsdFile) {
    $file = fopen($xsdFile, 'w');
    fwrite($file, "<?xml version='1.0' encoding='utf-8'?>\n");
    fwrite($file, "<schema xmlns='http://www.w3.org/2001/XMLSchema'>\n");
    fwrite($file, "<element name='name' type='string' />\n");
    fwrite($file, "</schema>\n");
    fclose($file);
}

//
// Appends a blank line at the end of the XML file.
// Does this cause a schema validation problem?
//
function createXmlFile($xmlFile) {
    $xml = new XMLWriter;
    $xml->openURI($xmlFile);
    $xml->startDocument('1.0', 'UTF-8');
    $xml->setIndent(1);

    $xml->startElement('name');
    $xml->text('jim');
    $xml->endElement();

    $xml->endDocument();
    $xml->flush();
}
?>

@Edward, do you believe there could be a regression in the schema validation component in the version of PHP on ubuntu that you are using? — DavidRR, Sep 06 '12 at 14:54
The problem turned out to be I was forgetting the root element, which for some reason causes schemaValidate to report "Extra content at the end of the document" without giving any other errors in the document, once I added the root element, I can now see other errors. — Edward Tanguay, Sep 13 '12 at 11:32

How to prevent XMLWriter from appending blank line to outputted XML file?

3 Answers3