提交表单失败后，PHP保留表单信息

你好 我正在mvc系统视图中构建表单，并且我希望所有插入的值都将保留，以防表单提交失败. 如何做到这一点:我尝试过(一个字段的示例):

Hello I am building a form in a mvc system view, and i want that all the inserted values will be kept,in case of form submit failure. How can this be done: i tried like (example for a field):

     <label for="user_firstname">Nume</label>
    <input id="user_firstname" type="text" name="user_firstname" value=<?= $_POST['user_firstmane'] ?> >
    <? if (isset($errors['user_firstname'])): ?>
    <span class="error"><?= $errors['user_firstname']; ?></span>
<? endif; ?> 

但是，当然，这在第一次(当未执行后期操作时)不起作用.

but of course, it doesn't work the first time (when no post action is done).

最简单的方法是什么?有什么想法吗?

what is the simplest way to do this? any ideas?

谢谢