How can I make my form input not return any results when it is inputted with an empty query?

Question

I want my form input not to act upon an empty search.

I don't want it to even go to the results page and show an error message.

SO

how can I have it so nothing happens when clicking the submit/pressing enter OR pressing space bar then enter?

Can this be done with javascript?

HTML:

 <form action="search.php" method="post">
 Search: <input type="text" name="term" /><br />
 <input type="submit" name="submit" value="Submit" />
 </form>

PHP:

<?php

$conn = mysql_connect("", "", "")
or die    (mysql_error());
mysql_select_db("testable");

if (!$conn) {
echo "Unable to connect to DB: " . mysql_error();
exit;
}

$term = addcslashes($term,'%_');

$term = "%" . $_POST["term"] . "%";



if (!mysql_select_db("weezycouk_641290_db2")) {
echo "Unable to select mydbname: " . mysql_error();
exit;
}

**if (isset($_POST['term']) && ($_POST['term'] !== '')) {
$term = $_POST['term'];
$safe_term = mysql_real_escape_string($term);
$sql = "SELECT FName,LName,Phone
FROM   testable
WHERE  FName LIKE '%". mysql_real_escape_string($term) ."%'";
$result = mysql_query($sql);
}**


if (!$result) {
echo "Could not successfully run query ($sql) from DB: " . mysql_error();
exit;
}

if (mysql_num_rows($result) == 0) {
echo "No rows found, nothing to print so am exiting";
exit;
}


while ($row = mysql_fetch_assoc($result)) {
echo '<br><br><div class="data1">';
echo htmlentities($row["FName"]);
echo '</div><br><div class="data2">';
echo htmlentities($row["LName"]);
echo '</div><br><div class="data3">';
echo htmlentities($row["Phone"]);
echo '</div>';
}

mysql_free_result($result);

?>

Answer 1

Preventing the form from being submitted via JS is a quick fix, but you still need to handle the possibility that someone could STILL submit a blank search:

if (isset($_POST['term']) && ($_POST['term'] !== '')) {
   $term = $_POST['term'];
   $safe_term = mysql_real_escape_string($term);
   $sql = "...."
   blah blah blah
}

note the use of mysql_real_escape_string(). It is THE safe method for strings in mysql queries. addslashes is a hideously broken piece of crap and should NEVER be used for SQL injection prevention.

Answer 2

您可以在JS中检查长度并中止它是空白的

Answer 3

Yes, you can do that using javascript. Add a javascript function to handle on click event of submit button.

<input type="submit" name="submit" value="Submit" onclick="submitForm(event)" />

Inside that javascript function, check whether textbox is empty or not

        function submitForm(event){
        var val = document.getElementsByName('term')[0].value;

        if (val==null || val.trim()==""){
        //document.getElementsByTagName('form')[0].submit();
         event.preventDefault();
         return false;

        }
        else {
          return true;
        }

        }

If empty, prevent default event and return false => prevent submission if not empty, return true => submit the form.