bootstrap php联系表单值显示错误<br /> <b>通知</ b>：未定义变量：<b> C：\ x \ testForm.php </ b>中的myThema <b> 105 </ b> <br />

Question

I am using bootstrap and I want to create a contact Form. I have create a File with the name testForm.php and there I have written my php and my html code(should I make a different files? one for php and one for html?). My file starts with the php code to and after the html code. As soon as I put an <?php echo.... in the html area, everywhere, appears all the time in the site Undefined index: .for example

Now I m trying only with one parameter :thema to see if it works and how it works and if I put something to value comes the result like the picture above. My php code:

<?php
if (isset($_POST["submit"])) {
    $thema = $_POST['thema'];



    // Check if thema has been entered
    if (!$_POST['thema']) {
        $errThema = 'Please enter your thema';
    }


}

?>

and my html code:

<!-- MAIN SEITE -->
<h4><p class="text-primary"><u>Neuanforderungsformular</u></p></h4>

<!-- START FORM -->
<form method="post" role="form" action="testForm.php">
<!-- Thema Feld -->
<div class="form-group">
    <label for="usr">Thema / Title:</label>
    <input type="text" id="thema" name="thema" class="form-control input-lg" value="<?php echo htmlspecialchars($_POST['thema']); ?>">
</div>
<!-- Email Adresse Feld-->
<div class="form-group">
    <label for="exampleInputEmail1">Email address</label>
    <div class="input-group col-sm-5">
    <input type="text" class="form-control input-lg" placeholder="Ihre Email Addresse" aria-describedby="basic-addon2">
    <span class="input-group-addon" id="basic-addon2">@teswt.de</span>
</div>

how can I fix the provbem so my contact form will works?

Answer 1

Try this:

<?php
if (isset($_POST["submit"])) {
    if (isset($_POST['thema'])){
        $thema = $_POST['thema'];
    } else {
        $thema = 'Please enter your thema';
    }
}
?>

You should check first if $thema has been set. What you did is you are using $_POST['thema'] without checking, thus the error appearing in the text field