函数内的PHP函数[重复]

Question

This question already has an answer here:

• Reference: What is variable scope, which variables are accessible from where and what are “undefined variable” errors? 3 answers

I created a simple function that needs to display some information.

Some of this information comes from the database.

But, the database handler is not recognized within this function, therefor, I get the following errors:

Notice: Undefined variable: db in censored\controller\edit_mails.php on line 82

Fatal error: Call to a member function get_results() on null in censored\controller\edit_mails.php on line 82

I'm using the ezSQL database handler

The function:

function MessageSelector() {
$emails = $db->get_results("SELECT * FROM settings_emails WHERE cat = '$edit_type'" );
if(empty($emails)) {
//There are no messages to select
        } 
else { 
        //Create an option for each message
        foreach ($emails as $email):  
            echo "<option value=\"", $email->title , "\" onclick=\"location.href='edit_emails.php?x=", $edit_type , "&mail=",$email->id,"';\">", $email->title , "</option>";
        endforeach;
        ";}  
}

Database Handler:

require_once ADMIN_DB_DIR . '/ez_sql_core.php';
require_once ADMIN_DB_DIR . '/ez_sql_mysql.php';
global $db;
$db = new ezSQL_mysql($dbuser, $dbpassword, $dbname, $dbhost);

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Answer 1

Pass in $db as a parameter into your function for it to be used in the scope of the function.

Also, you have some weirdness in your foreach. Concatenate normally and don't forget to define $edit_type

function MessageSelector($db) {
     $emails = $db->get_results("SELECT * FROM settings_emails WHERE cat = '$edit_type'" );
     if(empty($emails)) {
           //There are no messages to select
     } else { 
        //Create an option for each message
        foreach ($emails as $email) {  
            echo "<option value=\"". $email->title . "\" onclick=\"location.href='edit_emails.php?x=". $edit_type . "&mail=" . $email->id . "';\">". $email->title . "</option>";
        }
     }  
}