php SimpleXML attributes are missing

问题:

I have the following xml document here: Edit: (see below for sample)

I am using php/SimpleXML to covert it to an object to read it:

$xmlContent = file_get_contents($path . '/test.xml');
$tablesRaw = new SimpleXMLElement($xmlContent);
echo '<pre>';
print_r($tablesRaw);
echo '</pre>';

When I print_r I see attributes for field but attributes for acceptable-value do not show. Here is an example of the raw xml (I need the value attribute):

<acceptable-value value="0">
    Unknown
</acceptable-value>

This is what I see when I print_r:

[acceptable-values] => SimpleXMLElement Object
                                            (
                                                [acceptable-value] => Array
                                                    (
                                                        [0] => 
                    Unknown

                                                        [1] => 
                    Invalid

                                                        [2] => 
                    Deleted

                                                        [3] => 
                    Valid/Good

                                                        [4] => 
                    Inactive

                                                    )

                                            )

Any clues why the attributes are not showing? Thanks in advance.

EDIT: Request for some of the xml:

<field name="Address1Type" type="String"/>
<field name="Address2Street1" type="String"/>
<field name="Address2Street2" type="String"/>
<field name="Address2Type" type="String"/>
<field name="Address3Street1" type="String"/> 
<field name="Status" type="Integer" access="R">
            <acceptable-values>
                <acceptable-value value="0">
                    Unknown
                </acceptable-value>
                <acceptable-value value="1">
                    Invalid
                </acceptable-value>
                <acceptable-value value="2">
                    Deleted
                </acceptable-value>
                <acceptable-value value="3">
                    Valid/Good
                </acceptable-value>
                <acceptable-value value="4">
                    Inactive
                </acceptable-value>
            </acceptable-values>
        </field>

回答1:

The simple answer here is not to use print_r() with SimpleXML objects. Because they are wrappers around non-PHP data, functions like that which would normally show the "whole" object don't really reflect what you're looking at.

The way to access an attribute with SimpleXML is to use the attribute name as though it was an array key ($node['attribute']); this does not mean that there is an array somewhere with that key, it is a function-call in disguise.

If you want to get a feel for which nodes you're looking at while writing SimpleXML code, check out this simplexml_dump() function which I wrote (feedback welcome).

回答2:

First, you have to get the SimpleXMLElement object. In this case:

$xmlContent = file_get_contents($path . '/test.xml');
$tablesRaw = new SimpleXMLElement($xmlContent);
$elements = $tablesRaw->table[22]->fields->field[31]->{'acceptable-values'}->children();

Now, you can iterate over each acceptable-value object and use the attributes() method:

foreach($elements as $element) {
    echo $element->attributes()->value . " ";
    echo trim($element[0]) . "\n";
}

With your XML, that will print:

0 Unknown
1 Invalid
2 Deleted
3 Valid/Good
4 Inactive

It doesn't rely on the array index, because the call to attributes() gets the actual attributes of the element. And ->value gets the attribute with the name "value".