Unchecked checkbox values

> hidden field’s POST value gets overwritten by the activated checkbox’s

This is not correct. Both values will get submitted, HTML allows mutliple values with the same name. That is you’ll get something like:
process.html?box1=0&box1=1 — checked
process.html?box1=0 — unchecked

now it may work for you, but your server side code must be prepared to handle multiple values for the same variable, but saying that it “gets overwritten” is incorrect.

gligeti,

you’re right, technically both do get posted, however by the time it gets to your server-side script you’re likely only going to see the latter valeu = the 1. In PHP $_POST[‘box1’] would output a 1.

Let’s keep the discussion going – if there’s a better solution, please, please, please post it! It can only help us all out!

If you’re using an array– it posts both values to the array.
Example:

both 0 & 15929
get into

review0[0]=0
review0[1]=15929

any solutions?

If you know what you are expecting your POSTed data to be, which you should as you made the HTML form, then just create a new array from the POSTed one.

You need to name the keys of the checkbox name array:
EG

When the form is posted, make a new array using ALL the key names you KNOW are used in the checkbox names

Then use that new array to loop all keys. With each loop, check if the current key from your new array matches a key in the posted array.
If no match then that key value is NO, if it is matched then that key value is YES.
It’s IMPORTANT when you make the new array to make the keys in the same order as they appear in the html form or the loop wont match them in order and wont work correctly

Here is the full script

form.html page

eat fruit
eat bread
eat apples

post.php page

//get check boxes user DID tick
$post_array = $_POST[‘eat’];

//make new array
$array_keys = array(“fruit” => “”, “bread” => “”, “apples” => “”);

//loop through new array, if key is matched then value is yes
//else value is no

foreach ($array_keys as $key => $value){
if (array_key_exists($key, $post_array)){
$new_array[$key]=”yes”;
}else{
$new_array[$key]=”no”;
}
}

Your $new_array is now all the values submited fom tickboxes from the form, with the same key names, and for each one the user didnt tick the key is added and a value of “no” inserted.
This makes it simple to insert into a db where user settings is a yes or no
you can of course change what it outputs for the “yes” and “no” as desired

Greg

Ok, I’m trying one more time then giving up

form.html page

<input type="checkbox" name="eat[fruit]" value="yes" />
<input type="checkbox" name="eat[bread]" value="yes" />
<input type="checkbox" name="eat[apples]" value="yes" />


Using arrays in form fields, as we’ve seen, can be a difficult or tedious thing to work with.

Here are a few thoughts I’ve had about this:
1. In the past when I’ve used the arrayed fields, I was less concerned with the key than I was the actual value of the field being submitted. One example that comes to mind is having multiple file uploads from one page. Sure you can map each numeric key to a field in your database, but that can be solved by creating several different named fields: file1, file2, file3, etc. I’ve used the array for situations where I don’t know how many will be submitted, which ones will be submitted, or each key, regardless of order, corresponds to a new row in a database table.

2. Rather than creating arrays that look like game[baseball], game[soccer], game[football], could you not just create single variables: baseball, soccer, football? Greg, your work-around is fine, but it accomplishes the same thing as creating $sports=array(baseball, soccer, football) and doing a foreach() on your POST array and seeing if the post key is in the $sports array.

3. I thought about what could be the best of the best solutions: fully populating the object, e.g. $sports, with all the data from the database and simply pulling the field default values when the POST field doesn’t exist (implying the unchecked checkbox). But then I got to realizing that there are going to be cases where not every database field corresponding to my $sports object is going to be represented in an HTML form, which would default the DB field every time $_POST[‘football’] wasn’t there. So I was wrong – it’s not the best of the best… for me at least.

4. How about creating an array of expected keys and default values for checkboxes in your PHP scripts? You can do that, but I think it’s too much extra work and specificity in larger apps. As much as possible I wan my apps to work with minimal additional coding. I would like to be able to extend my Games class with a BoardGame class without having to rewrite Games very much (at all), nor write a lot of code just to get BoardGame working. In my opinion $BoardGame->save(); should just work without having to write another save() method, except for those cases where differences in relational database schema need to be addressed.

Food for thought….

Thanks man, that’s brilliant…

great blog..

Just wanted to let you know I appreciate you posting this solution. Even though it is overwriting a value, and that’s not necessarily standard practice, and might cause problems in other situation, it fit my scenario perfectly and has yet to cause any problems.

Kudos,
joe

a wonderful simple way to solve this “annoying” issue, i would also suggest creative a small javascript that can update the value on change, this would be difficult and might add more code to your “simple” form for new coders, but it’s more accurate and more dynamic, anyways, as far as a form with one or two check boxes this one is a nice small trick 🙂 good jab cam.

How do you get this to work if you do not use PHP? I need to post to a txt file all checkbox fields (checked and unchecked, different value for each) to input into excel as csv file. If no field value is posted, the field is blank in the csv eg does not exist.

THANK YOU! A simple solution to a painful, small and irritating problem.

Great solution, very much appreciated. The CakePHP documentation needs to have a gigantic “GOTCHA” section devoted to this stuff. Beginners like myself have wasted countless hours on nuances that weren’t otherwise obvious.

wowwwwwww…. yipeeee !!!! thanks a lot… brilliant !!!!

Fuckin hell! 😀

Ive been going crazy about this shit for a couple of months now! AND FINALLY SOME ONE DOES THE TRICK! 😀

Cant thank you enough!

I used Greg’s original thinking and it worked great for me… that is, passing the values inside defined arrays: data[1], data[2], data[3]… then in my php script a loop does the rest, if data[1] is not checked then it is null… which will lead me to:
data[1] = ”;
data[2] = ‘Y’;
data[3] = ‘Y’;

the importance is that it keeps its order that it can be called and compared whenever required…

I was looking for this solution for 2-3 hours. Thank you very much 🙂

IT’s great information. TXH!

etc…
And you can use that trick with arrays =)

Pah, I try like this.

using name=”box[0]” , “box[1]”… with both, hidden and checkbox (same number)

<code

>

serverside for-loop to account for unchecked checkbox values of -1

ArrayList deleteAL = new ArrayList();
for (int ii = 0; ii < deleteAL.Count; ii++)
{
if ((deleteAL[ii]).ToString() != "-1" && ii != 0)
{
deleteAL.RemoveAt(ii – 1);
}
}
So checked, checked, unchecked would return value, value, -1

Thanks for this post. Incidentally I combined this technique and some common sense for a simple solution when using arrays. Assuming you have an index you are keeping track of when generating your form (simple enough to add to any script generating the form from retrieved data). All you need to do is add the (same) index to your array for both the hidden and checkbox inputs.

I’m showing this assuming php, but it’s simple enough to extend to whatever you need:


...

...


Hope this helps and thanks again for this post!

last try… removing html brackets…

input type=”hidden” name=”field[“.$index.”]” value=”default”
input type=”checkbox” name=”field[“.$index.”]” value=”checkedval”

Great idea! I was stuck on my code and was coding so many lines to get it work.
Many thanks Cameron!

Nice work, Thanks

The code got stipped off.. Now, trying to add without html tags.

input type=’checkbox’ id=’cbMyVar’ onChange=’document.getElementById(“hdnCbMyVar”).value=(this.checked?1:0)’

input type=’hidden’ name=’cbMyVar’ id=’hdnCbMyVar’ value=’0′

I am unable to add the code. Trying again without the html tags..

input type=’checkbox’ id=’cbMyVar’ onChange=’document.getElementById(“hdnCbMyVar”).value=(this.checked?1:0)’

input type=’hidden’ name=’cbMyVar’ id=’hdnCbMyVar’ value=’0′

Thanks, I used the similar logic to solve another problem, where I want to keep the id associated with the dynamically created check boxes.

Thanks so much. I’ve been looking for a way to do this for ages. You’ve made my day!

I should have thought about that earlier…

Thanks a lot that did the trick and works perfect….!

I always use a simple php function to “normalize” checkbox input from a post/get…

function checkbox_value( $key ) {
return (isset($_REQUEST[$key]) && ($_REQUEST[$key]==’1′))?1:0;
}

html:

function call: $check = checkbox_value(‘checkme’);
or: $_REQUEST[‘checkme’] = checkbox_value(‘checkme’);

Hi thanks alot for this great idea… i was stuck on this issue and you provided with me the solution

Thanks alot again

ugh. html. i remember that fracking checkbox nonsense from the late 1990s. it still impacts people in 2011.
it took over 10 years to figure that solution! now that is genius clever thinking. it should be bundled with the checkbox rendering code.

YEAH!
in my case is very useful for a form generator

SQL> select * from week;

MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY SUNDAY
———- ———- ———- ———- ———- ———- ———-
0 0 0 0 0 1 1

how to select the above fields which contain the value 1 using sql query.pls help me

I have a CGI program that had this problem, but I was using array as the field name. So here’s what I did:

HTML:

CGI Handling:

  idx = 0
  while idx < len(POST['v']):
    v = POST['v'][idx]
    if v == 'hide':
      v = ""
    else:
      # Skip the next "hide" value
      idx += 1
    idx += 1

but it can possible without form submit ??????
Please reply

Wonderful solution, thank you so much!