PHP Form Submission: Recognize Image Input Buttons

By  on  

As you probably know, you can recognize a form submission from a "submit" input type by placing the following code in the "processing" PHP script:

if(isset($_POST['submit'])) { /* do stuff */ }

Did you know, however, that when using an "image" input type to submit the form, the above wont work? You need to add a "_x" to the field name in PHP:

if(isset($_POST['submit_x'])) { /* do stuff */ }

Odd, huh? This works the same when using a form "GET" method.

Recent Features

  • By
    Send Text Messages with PHP

    Kids these days, I tell ya.  All they care about is the technology.  The video games.  The bottled water.  Oh, and the texting, always the texting.  Back in my day, all we had was...OK, I had all of these things too.  But I still don't get...

  • By
    How I Stopped WordPress Comment Spam

    I love almost every part of being a tech blogger:  learning, preaching, bantering, researching.  The one part about blogging that I absolutely loathe:  dealing with SPAM comments.  For the past two years, my blog has registered 8,000+ SPAM comments per day.  PER DAY.  Bloating my database...

Incredible Demos

  • By
    CSS Kwicks

    One of the effects that made me excited about client side and JavaScript was the Kwicks effect.  Take a list of items and react to them accordingly when hovered.  Simple, sweet.  The effect was originally created with JavaScript but come five years later, our...

  • By
    Six Degrees of Kevin Bacon Using MooTools 1.2

    As you can probably tell, I try to mix some fun in with my MooTools madness but I also try to make my examples as practical as possible. Well...this may not be one of those times. I love movies and useless movie trivia so naturally I'm...

Discussion

  1. The _x and _y represent the coordinate location you clicked the image at.

  2. Think this is only an issue with IE.

  3. Yeah. The _x- and _y-coordinates are great for improving the security of a form! I’ve used this to determine if the form has been filled by a human. A spam-bot won’t submit any coordinates but a human has to click on the button and so there will always be coordinates (you’ll have to deactive submitting with the ENTER-button).

  4. @Matthias: Good point on the security enhancement — I’ve never though of that!

  5. Braxo

    @ Matthias

    Thanks for posting your comment. I think telling the user that the ENTER button has been deactivated for bot protection is easier than having the user type in a captcha.

    I’ll definitely be looking into that method and most likely incorporating it into my projects.

  6. @Braxo – Wait – “Enter button” is deactivated? How would this affect someone who cannot use a mouse/relies on accessibility tools to fill out forms and the like?

    Some sites cannot get away with it (coughtargetcough).

  7. You can save yourself the trouble and just give the input a name attribute and check for that. Saves from changing code in two places (the input and the PHP submit validation).

    <input type="image" src="image.png" name="submitted" value="Submit" />

  8. I should clarify that…

    It saves from changing code in 2 places should you want to change to/from an image submit or a standard submit.

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!