Php ，我想这就是重点：）你的session_start（）呼叫在哪里？@Florian嗯，我想这就是重点：）哦，哇，我不敢相信我真的错过了。这很尴尬。但是感谢您对数据设置器函数的建议。我不知道没有必要检查是否设置了会话。哇，我不敢相信我真的错过了。这很尴尬。但

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，我想这就是重点：）你的session_start（）呼叫在哪里？@Florian嗯，我想这就是重点：）哦，哇，我不敢相信我真的错过了。这很尴尬。但是感谢您对数据设置器函数的建议。我不知道没有必要检查是否设置了会话。哇，我不敢相信我真的错过了。这很尴尬。但是感谢您对数据设置器函数的建议。我不知道没有必要检查会话是否已设置。

function data_setter($name) {
    if (isset($_SESSION[$name])) {
        return $_SESSION[$name];
    }
}

function show_form() {
    return '
        <h1>E-Mail-Vorbereitung<br /><br /></h1>
        <form action="' . $_SERVER['REQUEST_URI'] . '" method="post">
            <table>
                <tr>
                    <td><label for="anrede">Anrede</label></td>
                    <td>
                        <select name="anrede" id="anrede" class="staff_form">
                            <option id="select" disabled selected> -- Wähle eine Option -- </option>
                            <option id="frau" value="frau">Frau</option>
                            <option id="herr" value="herr">Herr</option>
                        </select>
                    </td>
                </tr>
                <tr>
                    <td><label for="name">Name</label>
                    <td><input value="' . data_setter('receiver') . '" type="input" class="staff_form" name="receiver" id="name" placeholder="Name des Empfängers eingeben" /></td>
                </tr>
                <tr>
                    <td><label for="email">E-Mail</label></td>
                    <td><input value="' . data_setter('email') . '" type="input" class="staff_form" name="email" id="email" placeholder="E-Mail des Empfängers eingeben" /></td>
                </tr>
            </table>
            <br /><input name="sent" type="submit" value="Daten prüfen" />
        </form>
    ';
}

function mailsender() {
    if (isset($_POST['sent']) &&
        isset($_POST['anrede']) && !empty($_POST['anrede']) &&
        isset($_POST['receiver']) && !empty($_POST['receiver']) &&
        isset($_POST['email']) && !empty($_POST['email'])
    ) {
        if (!is_email($_POST['email'])) {
            $_SESSION['receiver'] = $_POST['receiver'];
            $_SESSION['email'] = $_POST['email'];
            var_dump($_SESSION);

            echo '
                <h1>Error</h1>
                <p>Die eingegebene E-Mail-Adresse ist nicht gültig. Hast du dich vielleicht vertippt?</p>
                <FORM>
                    <INPUT TYPE="submit" onClick="window.location.href = "' . $_SERVER['REQUEST_URI'] . '";" VALUE="Nochmals probieren">
                </FORM>
            ';
        }
        else {
            // Delete sessions
            if (isset($_SESSION['anrede'])) { unset($_SESSION['anrede']); }
            if (isset($_SESSION['receiver'])) { unset($_SESSION['receiver']); }
            if (isset($_SESSION['email'])) { unset($_SESSION['email']); }

            global $wpdb;
            $table_name = "yc_customers";
            if($wpdb->get_var("SHOW TABLES LIKE '$table_name'") == $table_name) {
                $myrows = $wpdb->get_results( "SELECT email FROM yc_customers" );
                foreach ($myrows as $myrow) {
                    // Doing sumth here

                }
            }
            echo '
                <h1>Daten valid</h1>
                <p>Super, die Daten wurden geprüft und die Firma ist in der Your-Click-Datenbank <strong>nicht vorhanden</strong>.</p>
            ';
        }
    }
    else {
        // Set sessions
        if (isset($_POST['receiver']) && !empty($_POST['receiver'])) { $_SESSION['receiver'] = $_POST['receiver']; }
        if (isset($_POST['email']) && !empty($_POST['email'])) { $_SESSION['email'] = $_POST['email']; }

        // Validating
        if ($_POST['sent']) {
            // Anrede
            if (!isset($_POST['anrede']) || empty($_POST['anrede'])) {
                echo '
                    <div class="alert alert-danger" role="alert">
                        <span class="glyphicon glyphicon-exclamation-sign" aria-hidden="true"></span>
                        <span class="sr-only">Error:</span>
                        Bitte wähle eine Anrede aus.
                    </div>
                ';
            }
            // Receiver
            if (!isset($_POST['receiver']) || empty($_POST['receiver'])) {
                echo '
                    <div class="alert alert-danger" role="alert">
                        <span class="glyphicon glyphicon-exclamation-sign" aria-hidden="true"></span>
                        <span class="sr-only">Error:</span>
                        Bitte gebe den Namen des Empfängers ein.
                    </div>
                ';
            }
            // E-Mail
            if (!isset($_POST['email']) || empty($_POST['email'])) {
                echo '
                    <div class="alert alert-danger" role="alert">
                        <span class="glyphicon glyphicon-exclamation-sign" aria-hidden="true"></span>
                        <span class="sr-only">Error:</span>
                        Bitte gebe die E-Mail-Adresse des Empfängers ein.
                    </div>
                ';
            }
        }
        echo show_form();
        var_dump($_SESSION);
        // Set the chosen option
        if (isset($_POST['anrede']) && !empty($_POST['anrede'])) {
            echo '<script>$("#select").prop("selected", false);</script>';
            if ($_POST['anrede'] == 'frau') {
                echo '<script>$("#frau").prop("selected", true);</script>';
            }
            elseif ($_POST['anrede'] == 'herr') {
                echo '<script>$("#herr").prop("selected", true);</script>';
            }
        }
    }
}
add_shortcode('mailsender', 'mailsender');