validate input is not empty on submit

Question

The following echo statement creates an empty textbox and a submit button using php.

    echo"<td><form id=\"edit\" name=\"edit\" method=\"post\" action=\"../assets/modules/coursemanager/process.cm.php\" onsubmit=\"return check_edit();\">
    <input type=\"text\" size=\"3\" id=\"edit_places\" name=\"edit_places\" value=\"\" />
    <input type=\"hidden\" name=\"sid\" value=\"".$sid."\" />
    <input type=\"submit\" name=\"Submit\" value=\"edit places\" /></form></td>";

This is the validation JavaScript I am using, but the above form is ignoring it.

  function check_edit(){
      var notempty=document.forms["edit"]["edit_places"].value;
        if(notempty==null || notempty==""){
           alert("Please enter the new number of available places and try again");
           return false;
      }else{    
           return true;
      }
  }

I would be very grateful if someone could show me my error.

Not sure if this is your problem but notempty==nul || notempty=="" should be notempty==null || notempty=="". Also because of how Javascript works, a simpler way of saying that is if(!notempty), which will handle null and "" but also undefined false and 0. If you only want to check null/"", you should use === instead of just ==. — machineghost
– machineghost, Commented Jan 11, 2014 at 3:45
Ah yes, thank you for that Josh. I have corrected that in the post :) — Twobears
– Twobears, Commented Jan 11, 2014 at 4:14

knrz · Accepted Answer · 2014-01-11 03:53:13Z

1

You can check the length of the input.

value = document.forms["edit"]["edit_places"].value.replace(/\s+/g, '')

if (value.length > 0) {
  return true;
} else {
  alert("Please enter the new number of available places and try again");
  return false;
}

answered Jan 11, 2014 at 3:53

knrz

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1 Comment

Twobears Over a year ago

Thank you for your answer Knouroozi. I have resolved it as follows:

Twobears · Accepted Answer · 2014-01-11 04:20:32Z

0

I used an else statement in the processing script which does the trick and dispensed with the check_edit function.

    if($_POST['edit_places']!== ''){
    $id=$_POST['sid'];
    $z=$_POST['edit_places'];
    $sql = "UPDATE xtra_session SET places=$z WHERE xtra_session.id=$id";
    $add = $modx->db->query($sql);
    $msg = ($add? "available places has been updated" : "error: ".mysql_error());
    }
    else {
    echo "Please enter a number of places to change"; 
    }

Thank you for your valued suggestions.

answered Jan 11, 2014 at 4:20

Twobears

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