Call to a member function on a non-object

So I'm refactoring my code to implement more OOP. I set up a class to hold page attributes.

class PageAtrributes
{
private $db_connection;
private $page_title;


public function __construct($db_connection)
{
$this->db_connection = $db_connection;
$this->page_title = '';
}


public function get_page_title()
{
return $this->page_title;
}


public function set_page_title($page_title)
{
$this->page_title = $page_title;
}
}

Later on I call the set_page_title() function like so

function page_properties($objPortal) {
$objPage->set_page_title($myrow['title']);
}

When I do I receive the error message:

Call to a member function set_page_title() on a non-object

So what am I missing?

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最佳答案

It means that $objPage is not an instance of an object. Can we see the code you used to initialize the variable?

As you expect a specific object type, you can also make use of PHPs type-hinting featureDocs to get the error when your logic is violated:

function page_properties(PageAtrributes $objPortal) {
...
$objPage->set_page_title($myrow['title']);
}

This function will only accept PageAtrributes for the first parameter.

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I realized that I wasn't passing $objPage into page_properties(). It works fine now.

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I recommend the accepted answer above. If you are in a pinch, however, you could declare the object as a global within the page_properties function.

$objPage = new PageAtrributes;


function page_properties() {
global $objPage;
$objPage->set_page_title($myrow['title']);
}
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you can use 'use' in function like bellow example

function page_properties($objPortal) use($objPage){
$objPage->set_page_title($myrow['title']);
}
小开

There's an easy way to produce this error:

    $joe = null;
$joe->anything();

Will render the error:

Fatal error: Call to a member function anything() on a non-object in /Applications/XAMPP/xamppfiles/htdocs/casMail/dao/server.php on line 23

It would be a lot better if PHP would just say,

Fatal error: Call from Joe is not defined because (a) joe is null or (b) joe does not define anything() in on line <##>.

Usually you have build your class so that $joe is not defined in the constructor or

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Either $objPage is not an instance variable OR your are overwriting $objPage with something that is not an instance of class PageAttributes.

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It could also mean that when you initialized your object, you may have re-used the object name in another part of your code. Therefore changing it's aspect from an object to a standard variable.

IE

$game = new game;


$game->doGameStuff($gameReturn);


foreach($gameArray as $game)
{
$game['STUFF']; // No longer an object and is now a standard variable pointer for $game.
}






$game->doGameStuff($gameReturn);  // Wont work because $game is declared as a standard variable.  You need to be careful when using common variable names and were they are declared in your code.
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function page_properties($objPortal) {
$objPage->set_page_title($myrow['title']);
}

looks like different names of variables $objPortal vs $objPage


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