Check if a field/propertry exists in a variable of type object

Question

I am using Zend_Search_Lucene, to index my website. My site indexes are not entirely similar. Some have, few fields, and some have many fields. I am trying to create a similar index through different types of table, that's why i am encountering this kind of error.

Now, when I display the result. I call some fields, which are not present in all the result which generates the error. i tried to check it with isset but it seems it totally skips the row.

foreach ($hits as $hit) {
    $content .= '<div class="searchResult">';
      $content .= '<h2>';           
        $title = array();
        if(isset($hit -> name)) $title[] = $hit -> name;
        if(isset($hit -> title)) $title[] = $hit -> title;
            // This is the part where i get fatal error.
        $content .= implode(" &raquo; ",$title);
      $content .= '</h2>';
      $content .= '<p>'.$this->content.'</p>';
    $content .= '</div>';
}

How to check if there is anything such as $hit -> name is present in $hit

Does it skip the row or do you get a PHP error? You seem indecisive. — Jon, Apr 11 '11 at 14:20
Of course error `Fatal error: Uncaught exception 'Zend_Search_Lucene_Exception' with message 'Field name "name" not found in document` — mrN, Apr 11 '11 at 14:24
I just solved the problem, but keep in mind that if you had not given the exact error message I would never have been able to. In the future, please post *all relevant messages* when asking the question. Don't leave people guessing, it makes it harder for *you* to get help. — Jon, Apr 11 '11 at 14:54

Jon · Accepted Answer · 2014-01-20T10:13:55.660

The problem you are experiencing is very very specific and has to do with the Zend_Lucene_Search implementation, not the field/property exist check in general.

In your loop, $hit is an object of class Zend_Search_Lucene_Search_QueryHit. When you write the expression $hit->name, the object calls the magic __get function to give you a "virtual property" named name. It is this magic function that throws the exception if the value to be supplied does not exist.

Normally, when a class implements __get as a convenience it should also implement __isset as a convenience (otherwise you cannot really use isset on such virtual properties, as you have found out the hard way). Since this particular class does not implement __isset as IMHO it should, you will never be able to get the name "property" blindly without triggering an exception if the relevant data does not exist.

property_exists and all other forms of reflection will also not help since we are not talking about a real property here.

The proper way to solve this is a little roundabout:

$title = array();
$names = $hit->getDocument()->getFieldNames();
if(in_array('name', $names)) $title[] = $hit -> name;
if(in_array('title',$names)) $title[] = $hit -> title;

All said, I 'd consider this a bug in ZF and probably file a report, asking for the __isset magic method to be implemented appropriately on the types it should be.

`getFieldNames` do not return associative array. I have corrected your answer. — Starx, Apr 12 '11 at 02:48
Thanks, Jon. @Starx, I didn't knew you knew Zend Framework too. — mrN, Apr 12 '11 at 04:41
@mrN, I am also a newBie at this. But, try me before you post at SO. :P — Starx, Apr 12 '11 at 04:50

score 0 · Answer 2 · answered Apr 11 '11 at 14:20

0

You can try property_exists.

foreach ($hits as $hit) {
    $content .= '<div class="searchResult">';
      $content .= '<h2>';           
        $title = array();
        if(property_exists($hit, 'name')) $title[] = $hit -> name;
        if(property_exists($hit, 'title')) $title[] = $hit -> title;
            // This is the part where i get fatal error.
        $content .= implode(" &raquo; ",$title);
      $content .= '</h2>';
      $content .= '<p>'.$this->content.'</p>';
    $content .= '</div>';
}

answered Apr 11 '11 at 14:20

Paul DelRe

4,003
1
24
26

$hit, is not a class, its just a variable of type Object – mrN Apr 11 '11 at 14:23
I am not familiar with Zend, but it should work on any object from PHP's stdClass. I tested with: `$hit = new stdClass(); $hit->name = 'foo'; echo property_exists($hit, 'name') ? 't' : 'f'; > t` – Paul DelRe Apr 11 '11 at 14:33
1

It won't work correctly if the property does not exist in the first place but it is implemented using `__get` instead. – Jon Apr 11 '11 at 14:52
@Jon I see. Thanks for the insight into this Zend class. – Paul DelRe Apr 11 '11 at 15:48

score 0 · Answer 3 · answered Apr 11 '11 at 14:25

You can also use reflection to query what fields the object has and build your content in a more programmatic way. this is good if you have a ton of fields.

$reflector = new ReflectionClass( get_class( $hit ) );
foreach( $reflector->getProperties() as $property  ) {
    if( in_array( $property->getName(), $SEARCH_FIELDS )
        $title[] = $property->getValue( $hit );
}

more info here : http://php.net/manual/en/book.reflection.php

score 0 · Answer 4 · edited Sep 13 '11 at 20:22

0

# Verify if exists
$hits = $index->find('id_field:100');
if (isset($hits[0])) { echo 'true'; } else { echo 'false'; }

edited Sep 13 '11 at 20:22

Jérôme Verstrynge

57,710
92
283
453

answered Sep 06 '11 at 15:18

Brynner Ferreira

1,527
1
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21

score 0 · Answer 5 · answered Dec 04 '11 at 21:11

isset will work if you simply convert your object to an array first.

<?php
class Obj {
    public function GetArr() {
        return (array)$this;
    }
    static public function GetObj() {
        $obj = new Obj();
        $obj->{'a'} = 1;
        return $obj;
    }
}

$o = \Obj::GetObj();
$a = $o->GetArr();
echo 'is_array: ' . (\is_array($a) ? 1 : 0) . '<br />';
if (\is_array($a)) {
    echo '<pre>' . \print_r($a, \TRUE) . '</pre><br />';
}
echo '<pre>' . \serialize($o) . '</pre>';
?>

Check if a field/propertry exists in a variable of type object

5 Answers5