$_SESSION seems to retain only last value

Question

Please see the test page here https://wintoweb.com/sandbox/question_3.php I use $_SESSION to store results of DB searches but only the last value is stored in the session. Looks like the latter is emptied upon each search.

I've used session before on that server and had no problems. My code is probably faulty but I cannot figure it out. session_start is called at top of file.

<?php  
if(isset($_GET['search'])){

} else if(isset($_GET['display_this'])){
    $rets = getNames(); //The $rets will hold the value returned by your function getName(). 
    if(!empty($rets)){
        echo '</br><b>Your selections so far :</b></br></br>';
    }

    //But yet, only the last search is stored in the session (why?)   
    echo "Echo of session array : " . $_SESSION['author'] . "<br>";
}

function getNames(){
    $rets = '';
    if(isset($_GET['choices']) and !empty($_GET['choices'])){
        foreach($_GET['choices'] as $selected){
            $rets .= $selected . ' -- ';

    // This should add every $rets to the session array. Right?     
    $_SESSION['author'] = $rets; 
    //session_write_close();

        }
    }

    return $rets;
}
?>

I expect the session to retain all info from subsequent searches but only the last value is stored.

Answer 1

A couple of things. I'll explain within the code.

// make sure that the function is before it is called.
// computers execute code top to bottom, and so getNames wouldn't even exist yet
// so therefore your if statement (below) will always evaluate to false
function getNames($choices){
    // use parameters instead of $_GET inside of a function
    $rets = '';
    if(isset($choices) && !empty($choices)){
        foreach($choices as $selected){
            $rets .= $selected . ' -- ';

            // you need to append using '.=' not '=' otherwise all the data will be overwritten
            $_SESSION["author"] .= $rets; 
        }
    }

    return $rets;
}

// you shouldn't be checking if something isset and then doing nothing about it
// you might as well just be checking if it isn't.
if(!isset($_GET["search"]) && isset($_GET['display_this'])){
    $rets = getNames($_GET["choices"]);
    if(!empty($rets)){
        echo '</br><b>Your selections so far :</b></br></br>';
    }

    echo "Echo of session array : " . $_SESSION['author'] . "<br>";
}

// you need to move this to the end of your script, otherwise the session will be closed
// before the second iteration of your loop begins and you won't be able to change values
// or access them later on (like in the above if statement)
session_write_close();