php loop not working as expected

Question

I'm trying to swap all attribute id's at once from '$old' > '$new' then save the xml:

$reorder = array( 9=>"8", 8=>"5", 7=>"4", 6=>"3", 5=>"0", 4=>"1", 3=>"9", 2=>"7", 1=>"2", 0=>"6" );

    $objDOM = new SimpleXMLElement(some.xml, null, true);
    foreach ($reorder as $old => $new) {
       $picture = $objDOM->xpath('picture[@id="'.$old.'"]');
       $picture[0]["id"] = $new;
    }
    echo $objDOM->asXML();

The result below (doesn't match Array $reorder)

3 > 9
9 > 6
8 > 8
7 > 2
6 > 3
5 > 5
4 > 4
0 > 0
1 > 1
7 > 2

It seems to be switching the id's in sequence, so id's that have just been switched are then switched again if they come up later in the array.

What I'm doing wrong there? How can I get it to switch ALL the id's in one go?

Thanks... Andy

Have you omitted anything within the code you pasted?

tplaner
– tplaner

2010-11-03 13:16:57 +00:00
Commented Nov 3, 2010 at 13:16 — tplaner
– tplaner, Commented Nov 3, 2010 at 13:16

teemitzitrone · Accepted Answer · 2010-11-03 14:05:55Z

2

The answer are two loops

fist you search the xpath for the old id, store it in an array and then loop again to replace the stored results with the new id

$reorder = array(9 => "8", 8 => "5", 7 => "4", 6 => "3", 5 => "0", 4 => "1", 3 => "9", 2 => "7", 1 => "2", 0 => "6");

$objDOM = new SimpleXMLElement(
      '<pictures>
    <picture id="9">id was 9, should be 8 now</picture>
    <picture id="8">id was 8, should be 5 now</picture>
    <picture id="7">id was 7, should be 4 now</picture>
    <picture id="6">id was 6, should be 3 now</picture>
    <picture id="5">id was 5, should be 0 now</picture>
    <picture id="4">id was 4, should be 1 now</picture>
    <picture id="3">id was 3, should be 9 now</picture>
    <picture id="2">id was 2, should be 7 now</picture>
    <picture id="1">id was 1, should be 2 now</picture>
    <picture id="0">id was 0, should be 6 now</picture>
</pictures>');
$oldPicIds = array();

foreach ($reorder as $old => $new) {
   $oldPicIds[$old] = $objDOM->xpath('picture[@id="' . $old . '"]');
}

foreach ($reorder as $old => $new) {
   $oldPicIds[$old][0]['id'] = $new;
}

echo $objDOM->asXML();

Output:

<?xml version="1.0"?>
<pictures>
    <picture id="8">id was 9, should be 8 now</picture>
    <picture id="5">id was 8, should be 5 now</picture>
    <picture id="4">id was 7, should be 4 now</picture>
    <picture id="3">id was 6, should be 3 now</picture>
    <picture id="0">id was 5, should be 0 now</picture>
    <picture id="1">id was 4, should be 1 now</picture>
    <picture id="9">id was 3, should be 9 now</picture>
    <picture id="7">id was 2, should be 7 now</picture>
    <picture id="2">id was 1, should be 2 now</picture>
    <picture id="6">id was 0, should be 6 now</picture>
</pictures>

to save an array you could use array_pop to get the last occurrence of picture@id=xy. which should be the wanted one (read comments for drawbacks)

$reorder = array(9 => "8", 8 => "5", 7 => "4", 6 => "3", 5 => "0", 4 => "1", 3 => "9", 2 => "7", 1 => "2", 0 => "6");

$objDOM = new SimpleXMLElement(
      '<pictures>...</pictures>');

foreach ($reorder as $old => $new) {
   $picture = $objDOM->xpath('picture[@id="' . $old . '"]');
   $picture = array_pop($picture);
   $picture['id'] = $new;
}

echo $objDOM->asXML();

edited Nov 3, 2010 at 14:05

answered Nov 3, 2010 at 13:18

teemitzitrone

2,26017 silver badges15 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Andy Over a year ago

brilliant! (I would vote up your answer but I don't have enough points yet) nice simple explanation too, many thanks maggie.

teemitzitrone Over a year ago

its ok. what i forgot to mention: the array_pop-solution is only something for unique attribute occurrence and of course sorted. if you just swap the original positions of p.e 9 and 8 the array_pop-solution will fail

Josh Davis · Accepted Answer · 2010-11-03 14:08:55Z

0

Judging from the example contained in the question, I would simply iterate over all <picture/> elements and change @id accordingly. For instance:

foreach ($objDOM->picture as $picture)
{
    $id = (string) $picture['id'];
    $picture['id'] = $reorder[$id];
}

This assumes that $reorder has an entry for every @id used in the document. Otherwise, you'll need to use isset() to skip nodes that don't need to be changed.

answered Nov 3, 2010 at 14:08

Josh Davis

28.8k5 gold badges54 silver badges67 bronze badges

Collectives™ on Stack Overflow

php loop not working as expected

2 Answers 2

2 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related