undefined index in multidimensional array

Question

I'm using amazon products API.

$ItemAttr = $Item['ItemAttributes'];

Now $ItemAttr contains a multidimensional array.

if(is_array($ItemAttr["Author"])){$Author = implode(", ", $ItemAttr["Author"]);
}else{
$Author = $ItemAttr["Author"];}

Now when i use the above code i'm getting Undefined index: Author in line 1 and line 3

I tried like this

if(isset($ItemAttr["Author"])) {
if(is_array($ItemAttr["Author"])){$Author = implode(", ", $ItemAttr["Author"]);
}else{
$Author = $ItemAttr["Author"];}
}

It eliminates that error.

But later, When I use code like this $RetVal = array( 'Author' => $Author); i'm getting Undefined variable : Author error

Can anyone tell me the proper way?

Please note: $Item['ItemAttributes']; may or may no contain Author key. I mean if the returned product is a book, the array will return author key. Else it will not..

David Müller · Accepted Answer · 2012-11-18 17:26:24Z

2

Initialize the empty variable $Author on top?

$Author = ""; //initialize here

if(isset($ItemAttr["Author"])) 
{
    if(is_array($ItemAttr["Author"]))
    {
        $Author = implode(", ", $ItemAttr["Author"]);
    }
    else
    {
        $Author = $ItemAttr["Author"];
    }
}

answered Nov 18, 2012 at 17:26

David Müller

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Comments

HenchHacker · Accepted Answer · 2012-11-18 17:38:45Z

I implemented the amazon books api just last month and i remember this exact same problem. How lucky are you as i never had me to help :(

Amazon is very annoying because there is no consistency within their returned structure (well, except for what's below, but that makes it annoying to consume):

if one item is returned, it's an OBJECT
if multiple items are returned, it's an ARRAY
if nothing is returned, NOTHING exists at all

Personally i think they should have used empty arrays at least, and stick to arrays. You can always add objects to arrays >< but at least the structure would be consistant.

The way i got around it, was to create a new representation of the returned structure which GUARANTEED that everything was an array and that the WHOLE STRUCTURE was pre-defined. This way i could later access the data knowing 100% that it won't give me errors like it doesn't exist or is being accessed as an object when it is an array.

First, create the structure how you want it to be such as:

$structure = array( 'isbn' => '', 'authors' => array(), 'pictures' => array(), 'title' => '' );

Then create a function or object method (depending on your style) to consume the amazon data returned and find what it can and insert it into your custom structure.

Remember to check that first it exists, and then if it is an array or an object so you know how to access it. It helps to print out a few returned results from amazon with a few different books.

Then, to access details about the book, you can rely on the data in the $structure ;) everything is an array, and everything is guaranteed to exist so doing:

foreach ($structure['authors']...

Won't produce an error that its not an array, doesn't exist or is in fact an object!!!

The sort of pseudo code would be:

$returned_amazon_data = get_amazon_data('http://amazon.com/api/book=1234567');
$book = consume_amazon_result($returned_amazon_data);
if ($book) {
//print out the authors, if no authors were found, will just stay blank as it's GUARANTEED to always be an array of strings
print implode($book['authors']);
}

Have fun! I know i did(nt)...

Thanks, remember that if you think newer answers answer your question better then you can change the marked answer to this question ;) you might not want to be so quick to mark your questions as answered because if i had saw you had marked it as answered - i would have skipped it! Others would likely do the same. Glad it was useful :)

Samuel Cook · Accepted Answer · 2012-11-18 17:25:46Z

1

You can combine your two conditional statements, as well as predefine $Author:

$Author = '';
if(isset($ItemAttr["Author"]) && is_array($ItemAttr["Author"])){
    $Author = implode(", ", $ItemAttr["Author"]);
}elseif(isset($ItemAttr["Author"])){
    $Author = $ItemAttr["Author"];
}

this should eliminate both errors.

answered Nov 18, 2012 at 17:25

Samuel Cook

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1 Comment

HenchHacker Over a year ago

That will remove the error, but you're still better creating a new structure to work with that has the guarantees you require. Writing that EVERYTIME you want to access something is paranoid coding at it's worst. I explained more in my answer about when i used the amazon api for book searches last month - now i avoid the amazon API when given the chance!!!

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