is_array() returns false on SimpleXml array element

Question

I try to check if SimpleXml element is an array.
I saw the given examples here on PHP doc and so it seems possible to check if a node is an array. But in my case, I cannot do it.

A var_dump($myElement) gives me:

object(SimpleXMLElement)#701 (4) { 
    ["@attributes"]=> array(1) { 
        ["id"]=> string(7) "5831377" 
    } 
    ["openPeriod"]=> string(10) "2016-04-01" 
    ["closePeriod"]=> string(10) "2016-05-31" 
    ["periods"]=> object(SimpleXMLElement)#703 (1) { 
        ["period"]=> array(2) { 
            [0]=> object(SimpleXMLElement)#707 (3) { 
                ["startPeriod"]=> string(8) "10:00:00" 
                ["endPeriod"]=> string(8) "12:30:00" 
                ["weekDays"]=> string(51) "monday,tuesday,wednesday,thursday,friday,saturday,sunday" 
            } 
            [1]=> object(SimpleXMLElement)#702 (3) { 
                ["startPeriod"]=> string(8) "14:00:00" 
                ["endPeriod"]=> string(8) "20:00:00" 
                ["weekDays"]=> string(51) "monday,tuesday,wednesday,thursday,friday,saturday,sunday" 
            } 
        } 
    } 
}

Depending $myElement, $myElement->periods->period could be an object or an array.

But in the given case, debug(is_array($myElement->periods->period)) returns false.

Could you tell me why?

EDIT
Here is the original XML element:

<openingPeriod id="5831487">
    <openPeriod>2016-04-01</openPeriod>
    <closePeriod>2016-05-31</closePeriod>
    <periods>
        <period>
            <startPeriod>10:00:00</startPeriod>
            <endPeriod>12:30:00</endPeriod>
            <weekDays>monday,tuesday,wednesday,thursday,friday,saturday,sunday</weekDays>
        </period>
        <period>
            <startPeriod>14:00:00</startPeriod>
            <endPeriod>20:00:00</endPeriod>
            <weekDays>monday,tuesday,wednesday,thursday,friday,saturday,sunday</weekDays>
        </period>
    </periods>
</openingPeriod>

what is ur PHP version!

Naincy
– Naincy

2017-02-26 12:29:29 +00:00
Commented Feb 26, 2017 at 12:29 — Naincy
– Naincy, Commented Feb 26, 2017 at 12:29
@Naincy, I use PHP7

fralbo
– fralbo

2017-02-26 14:36:08 +00:00
Commented Feb 26, 2017 at 14:36 — fralbo
– fralbo, Commented Feb 26, 2017 at 14:36

IMSoP · Accepted Answer · 2017-02-28 10:52:57Z

3

Your underlying assumption is wrong:

Depending $myElement, $myElement->periods->period could be an object or an array.

The result of the -> operator on a SimpleXMLElement object is always another SimpleXMLElement object. I'm not sure why there's so many mentions of is_array in the comments of the page you linked to, but I think they're all just making the same mistake. You may be fooled by var_dump or print_r telling you there's an array, but it's lying; that's just how the debug info displays multiple items with the same name.

You can access the object as though it was an array, using [0], foreach, etc, but these are all just convenience features of the object, not an actual array.

If you look at the official examples, you'll see that $myElement->periods->period is just short-hand for $myElement->periods[0]->period. So in most cases, you simply don't need to know if there are multiple children or just one, if you do foreach($myElement->periods->period as $period) for instance, the loop will always work. SimpleXML takes care of the different scenarios for you.

If what you really want to know is how many of a particular element there are, you can use count($myElement->periods->period). But again, you should not need to have any special cases in your code for when there's only one.

edited Feb 28, 2017 at 10:52

answered Feb 27, 2017 at 10:14

IMSoP

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2 Comments

fralbo Over a year ago

I think your answer is ok. Anyway my assumption is not totaly wrong. Depending on the $myElement I process, if I have 2 or more period in periods, var_dump tells ["period"]=> array(2), so an array of objects. If I have only have one period, then var_dump says ["period"]=> object(SimpleXMLElement). It is what I wanted to say and it's why I wondered how to use is_array(). But it seems I can use foreach in any case. Thanks.

IMSoP Over a year ago

@2ndGAB var_dump tells you that, but it's lying! There is no array there, it's just the way the debug output represents the fact that there is more than one child element with the same name. Under the hood, there's just a bunch of very un-PHP-like data representing the XML document, which is accessed on demand.

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