How to prevent the set of a get variable? - php

Question

I have a question. Let me explain this with an example.
I have this piece of code:
<form action="vehicles.php" method="get">
<span>Marca:
<select name="brand">
<option value="null" selected="selected"></option>
<option value="Volkswagen">Volkswagen</option>
<option value="Renault">Renault</option>
<option value="Peugeot">Peugeot</option>
<option value="Fiat">Fiat</option>
</select>
</span>
<span>Modelo:
<select name="model">
<option value="null" selected="selected"></option>
<option value="206">206</option>
<option value="Suran">Suran</option>
<option value="Passat">Passat</option>
<option value="Punto">Punto</option>
</select>
</span>
<input type="submit">
</form>
Is any way to prevent the assignment of those variables if the option selected is the "null" one?
If, for example, I select brand="Renault" and model="null" the url is
http://mywebpage.com/vehicles.php?brand=Renault&model=null
but it should be
http://mywebpage.com/vehicles.php?brand=Renault
I know how to unset the variables with "null" value after the form submission with PHP. Is any way to do it before the submission and after the variables are setted to "null".
I would like a cleaner url, free of "variable=null" results.
P/D: I don't have a native english speaking so feel free to edit my question. I wish you understand me.

Answer 1

I am afraid that you might need javascript to achieve what you want.
Take a look at this code:
<form action="vehicles.php" id="carForm" method="GET">
<span>Marca:
<select name="brand" id="brand">
<option value="none" selected>-</option>
<option value="Volkswagen">Volkswagen</option>
<option value="Renault">Renault</option>
<option value="Peugeot">Peugeot</option>
<option value="Fiat">Fiat</option>
</select>
</span>
<span>Modelo:
<select name="model" id="model">
<option value="none" selected="selected">-</option>
<option value="206">206</option>
<option value="Suran">Suran</option>
<option value="Passat">Passat</option>
<option value="Punto">Punto</option>
</select>
</span>
<input type="button" value="Submit" onclick="submitFormFilter();" />
</form>
Javascript : code will be like this:
<script>
function submitFormFilter(){
var myForm = document.getElementById("carForm");
var carBrand = document.getElementById("brand");
var carModel = document.getElementById("model");
if(carBrand.value === "none" || null){
carBrand.parentNode.removeChild(carBrand);
}
if(carModel.value === "none" || null){
carModel.parentNode.removeChild(carModel);
}
myForm.submit();
}
</script>
http://jsfiddle.net/7xzKP/1/
you can it try here.

Answer 2

Include the value attribute of your option tags.
<option value="" selected="selected">-</option>
You should really do this for all of your options.

Answer 3

if you don't want to use $_GET superglobal because of the url extension that it comes with try using $_POST instead. It will not have a url extension and it can still store values that you can later retrieve. Just be sure to change your method to equal POST instead of GET.
So the code for the form tag would change to:
<form action="vehicles.php" method="POST">
And you can later access it by (for example):
echo $_POST['brand'];
or
echo $_POST['model'];
as well, you probably want to add a value param to the values that you have in your option tag.
EDIT-
I've added this new section since you don't want to use POST even though I think you should.
You can stay with the GET method by doing this line of code:
<form action="vehicles.php" method="GET">
<span>Marca:
<select name="brand">
<option value="none" selected>-</option>
<option value="Volkswagen">Volkswagen</option>
<option value="Renault">Renault</option>
<option value="Peugeot">Peugeot</option>
<option value="Fiat">Fiat</option>
</select>
</span>
<span>Modelo:
<select name="model">
<option value="none" selected>-</option>
<option value="206">206</option>
<option value="Suran">Suran</option>
<option value="Passat">Passat</option>
<option value="Punto">Punto</option>
</select>
</span>
<input type="submit">
</form>
Let me know if that helps

Answer 4

You should set the value for the option tag of <select> :)

Answer 5

You's missing set value for option tag. you should set the value for option tag in select tag. With the blank value, you can assign it to a special value like zero(0)
<select name="model">
<option value="0" selected>-</option>
<option value="1">206</option>
<option value="2">Suran</option>
<option value="3">Passat</option>
<option value="4">Punto</option>
</select>
EDIT:
Ok. I got your point. You can import jquery to your page and make a check by javascript before you submit, if the value of select box is blank. you can remove it.
<script src="http://code.jquery.com/jquery-1.9.1.min.js"></script>
<script type="text/javascript">
$.ready(function(){
$("form").submit(function(){
if($("select[name='model']").val() == "0") $("select[name='model']").remove();
return true;
});
})
</script>