Override checkbox value set by PHP - php

Question

The form used to add a new item into the database and edit existing items is the same form. A "Mode" is passed into the form to tell it if were adding something new or to load the existing item for editing. So....
<input type="checkbox" name="fflreq" id="fflreq" value="<?=$row['FFLr']?>" <?php if ($row['FFLr']=="Yes") {echo 'checked';} ?>>
When a new item is being added, $row['FFLr'] doesn't exist so of course the value is BLANK or NULL or i guess 0 if i don't initially check the checkbox- The form processor coverts this into a "No" and inserts it into the database.
Now here is my problem - When I come back to a item and the form is in edit mode, the VALUE in this checkbox is now "No" - when I am clicking the checkbox to change its status, I see the checkbox become 'checked' but the value is not changing. in other words the click/check status is not setting the value of $_POST['fflreq'] to YES or 1.
I thought, that checking or unchecking a form checkbox replaces whatever is currently in the value='' attribute with a 1 or 0 to represent yes/no on/off or whatever. Why would the value pulled in from the database not change on form submission?

Answer 1

You need to do it in this way:
<input type="checkbox" name="fflreq" id="fflreq" value="Yes" <?php if ($row['FFLr']=="Yes") {echo 'checked';} ?>>
and when submit the form if the above checkbox is checked then you recieved the $_POST["fflreq"] in the form submit page and if it is not checked you recieve nothing in $_POST
so in the submit page you can do this:
$fflreq = "No"
if(isset($_POST["fflreq"]) && $_POST["fflreq"] == "Yes")
{
$fflreq = $_POST["fflreq"];
}
//then you can simply do anything with the $fflreq such as inserting it into database etc.
I hope this can be of some help.

Answer 2

That's not how it works. If you have "checked" the check box then it (along with it's value) will be sent with the post/get (i.e. submission) of the form. If you haven't checked it, then it won't be set...

Answer 3

If the checkbox is active, the browser sends the key/value pair defined in the input tag. However, if the checkbox is not active, nothing at all is sent for this checkbox.
There are two options to deal with this:
The clean option is to be aware of this on the server side, and assume that the checkbox was not active whenever no value comes through.
A more dirty variant is having a <input type="hidden"> tag just before the checkbox, using the same name, but the value you need to see when the checkbox is inactive. This way, when the checkbox is active, you'll still get the desired value from the checkbox, because it will overwrite the hidden value. However, if the checkbox is inactive, you'll get the value from the hidden field.

Answer 4

Not really, the check/unchecked status is read out by looking if the HTML name attribute value is present in the $_POST param.
You can check this with:
<?
if (!empty($_POST['fflreq'])){ /*checked*/ }
else{ /*unchecked*/ }
?>
The value of the HTML attribute value always stays whatever it is in your HTML. So no user interaction (except JS) can change that.
Working with PHP empty() function lets you bypass all the "Yes" "1" string int casting issues.
Further I would use ternary notation for these kind of things:
<input type="checkbox" name="fflreq" id="fflreq"
value="<?=$row['FFLr']?>" <?=(!empty($row['FFLr'])?'checked':'')?>>