Getting a form value without submitting a form

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Getting a form value without submitting a form

Default values in form generated by php script uniquely

jp_css

1:47 am on Mar 10, 2004 (gmt 0)

I have a complicated system I need to work around. One I don't care to explain too much, but essentially I would like to grab a form (I know how to do this) and then have php copy the value in a field to a variable. Is this possible?

lorax

2:27 am on Mar 10, 2004 (gmt 0)

Not without javascript or someother client-side tool but even then, the tool will have to submit the value back to the server. The problem is that the form doesn't exist on the server at the time the user is filling in the fields - it exists only on their computer screen. And there's no way for you to screen scrape or query the form without some interaction between their computer and your server - thus the need for a client-side tool.

dsandall

10:54 pm on Mar 11, 2004 (gmt 0)

Yes it is possible. It requires some (clever?) javascript. Perhaps if you can elaborate on the use,I can provide a better example of what you need to do.

Dwayne

brucec

3:22 am on Mar 12, 2004 (gmt 0)

dsandall and lorax are both right. Like dsandall said, it is definitely possible, and Javascript will accomplish it. Like lorax said, it cannot be done on the client side.

My solution is to use another server side PHP script which will be the target of the Action attribute in your form. So, it can be done, but maybe not efficiently.

So, here is how I would do it in javascript. I am not sure how inaccurate I am since like, dsandall, you need to provide us with a scenario.

1) First of all, give your form a name <form name="form1">

2) Next, you have to decide WHEN to gather that form field value using the right event handler. If you will take the variable when the user types in a value, you can use an onChange event handler in the INPUT HTML tag.

Or when the visitor moves to the next variable, an onUnfocus event handler.

Or after the entire form is filled out, an onSubmit event handler or an onClick event handler in a button (non-submit type)

3) Then, create a Javascript function in you <HEAD> to submit to another PHP script on the server and grab that value with the server-side PHP file.

So, in your function, you can code it like this:

function ProcessPhpVariable() {
document.form1.submit();
}

Form1 will have the Action attribute directed to another PHP file on the server.

I can see this working, but it will take two PHPs to do the job. One on the client and one on the server.

When the server-side PHP script is executed, it will become your client-side PHP script and it will have the vale in a variable. Maybe not the most efficient way, but it will work.

Bruce

brucec

3:34 am on Mar 12, 2004 (gmt 0)

What if instead of a function, you could try a document.write method in straight javascript in the <BODY> of the HTML and add some PHP that way?

Like
<script language="Javascript">
var PhpVariable = document.form1.field1.value;
document.write ("<?php");
document.write ("$PhpVal=", PhpVariable);
document.write ("?>");
</script>

I can see this working...I have not tried it, but it sounds like an interesting idea. You may need an onChange event handler to kick off the Javascript.

vincevincevince

5:30 pm on Mar 12, 2004 (gmt 0)

cURL may provide a way to get around it!

brucec

2:44 am on Mar 13, 2004 (gmt 0)

what is cURL? a function?

jatar_k

6:05 am on Mar 13, 2004 (gmt 0)

CURL, Client URL Library Functions [ca3.php.net]

jp_css

8:47 pm on Mar 13, 2004 (gmt 0)

How would I use cURL if and only if it would be a solution to this problem. Remember, these form values are already there when the page loads. I am just looking for a better way to get a javascript variable then sumbitting a hidden form.

vincevincevince

5:48 pm on Mar 16, 2004 (gmt 0)

Right, where did these form values come from?

If javascript has generated them, you can do pretty much any calculation javascript can do using php, and then php has the data before you even start.

If they are not on _your_ page... then you can use cURL to bring up the page, post values, and retrieve results, etc...

ergophobe

10:31 pm on Mar 16, 2004 (gmt 0)

If javascript has generated them, you can do pretty much any calculation javascript can do using php,

Like, for example, find 50% of the window width? PHP can't do that and javascript can't communicate that value to the server without submitting something.

Perhaps a few more details are in order?