php DOMDocument createTextNode from blob field(text) not showing data - php

Question

I am trying to create XML using DOMDocument from database table. All field types are showing in XML node except BLOB Type.
Below what I did:
$rs = ibase_query("SELECT * FROM mytable");
$coln = ibase_num_fields($rs);
$fieldnames = array();
for ($i = 0; $i < $coln; $i++) {
$col_info = ibase_field_info($rs, $i);
$fieldnames[] = array('name' => $col_info['name'], 'type' => $col_info['type']);
}
$doc = new DOMDocument('1.0');
$sth = ibase_query($dbh, $stmt);
$doc->formatOutput = true;
$root = $doc->createElement('FA_ARTIKEL');
$root = $doc->appendChild($root);
while ($row = ibase_fetch_object($sth, IBASE_TEXT)) {
$title = $doc->createElement('RECORD');
$title = $root->appendChild($title);
$text = $doc->createTextNode('');
$text = $title->appendChild($text);
foreach ($fieldnames as $value) {
switch ($value['type']) {
case 'VARCHAR':
$rtitle = $doc->createElement($value['name']);
$rtitle = $title->appendChild($rtitle);
$rtext = $doc->createTextNode($row->$value['name']);
$rtext = $rtitle->appendChild($rtext);
break;
case 'BLOB':
$rbtitle = $doc->createElement($value['name']);
$rbtitle = $title->appendChild($rbtitle);
$rbtext = $doc->createTextNode($row->$value['name']);
$rbtext = $rbtitle->appendChild($rbtext);
break;
default:
if ($row->$value['name']) {
$rtitle = $doc->createElement($value['name']);
$rtitle = $title->appendChild($rtitle);
$rtext = $doc->createTextNode($row->$value['name']);
$rtext = $rtitle->appendChild($rtext);
} else {
$rtitle = $doc->createElement($value['name']);
$rtitle = $title->appendChild($rtitle);
$rtext = $doc->createTextNode('0');
$rtext = $rtitle->appendChild($rtext);
}
break;
}
}
}
Header('Content-type: text/xml');
echo $doc->saveXML() . "\n";
ibase_free_result($sth);
ibase_close($dbh);
I tried with SimpleXMLElement also but it also failed. What I am missing?
My Database is Firebird and I set BLOB fields as
BLOB SUB_TYPE 1 SEGMENT SIZE 16384

Answer 1

PHPs DOMDocument expects UTF-8 strings. It is possible that the blob contains control characters/invalid unicode sequences. Try to put the data that breaks the XML into a variable and reduce your problem to the absolute minimum.
$blobData = $record['blobField'];
$document = new DOMDocument();
$document
->appendChild($document->createElement('foo'))
->appendChild($document->createTextNode($blobData));
echo $document->saveXml();
This way you can see if the blob data is really the problem or merely a symptom.
If the BLOB contains binary data you will need to convert it into a TEXT format. Atom feeds for example urlencode binary data that they want to embed. In this you will need to decode the value in the reading program.