How do I access the output of JavaScript function into the PHP to update DB

[bhasheth]

I'm new to PHP, can some one help that how do I do following. Your help will be grate... I'm sutck for this for past 3 days.

Scanario :

1. I'm displaying the module list to the user using HTML Table, following the code :

<?
print("<table name=$tblName width=100% cellspacing=\"2\" cellpadding=\"2\">");

print("<tr bgcolor=\"#FFDCB9\"> <td colspan=4 align=center > <b>Semester $semVal </b> (Select total modular weight between $ruleMin and $ruleMax.) </td> </tr>");

print("<tr bgcolor=\"#FFDCB9\"> <th colspan=4 align=center > </th> </tr>") ;

print("<tr bgcolor=\"#FFCC99\" border=1> ");

 print("<th> Module Code </th>");
 print("<th> Module Name </th>");
 print("<th> Weight </th>");
 print("<th> Select </th>");

print("</tr>");

for ($i=0; $i < $num_row ; $i++){
$row = mysql_fetch_array($result);
printf("<tr>");
print("<td width=17%> $row[mod_id] </td>");
print("<td> $row[title] </td>");
print("<td width=8%> $row[mod_wt] </td>");
$chk_name = $chbName. $i;
$mod_id = $row[mod_id];
print("<td width=8%> <input type=checkbox name=$chk_name onClick=\"fn_chk(this,$row[mod_wt],$semVal);\"> </td>");
printf("</tr>");
} // end of for loop

print("</table>");

2. I'm calling the JavaScript function fn_chk() when the checkbox is selected. Where I'm increasing or decreasing the total module weight for the semester and total module weight for year, depending upon the checkbox is checked / unchecked. Following is the code for the same.

function fn_chk(chkname, mod_wt, semVal){
var js_txt_sem1_tot = Number(document.frm_bsc_cs.txtSem1Tot.value);
var js_txt_tot_crd = Number(document.frm_bsc_cs.yearTot.value);
var js_txt_sem2_tot = Number(document.frm_bsc_cs.txtSem2Tot.value);

if (semVal == 1){
	if (chkname.checked){
			js_txt_sem1_tot += mod_wt;
			js_txt_tot_crd += mod_wt;

			}
	else{
			js_txt_sem1_tot -= mod_wt;
			js_txt_tot_crd -= mod_wt;}
document.frm_bsc_cs.txtSem1Tot.value = js_txt_sem1_tot; 
 }

if (semVal == 2){
	if (chkname.checked){
			js_txt_sem2_tot += mod_wt;
			js_txt_tot_crd += mod_wt;}
    else{
			js_txt_sem2_tot -= mod_wt;
			js_txt_tot_crd -= mod_wt;}
document.frm_bsc_cs.txtSem2Tot.value = js_txt_sem2_tot; }

document.frm_bsc_cs.yearTot.value = js_txt_tot_crd;

} // end of function fn_chk()

I have to have the list of selected modules for the both the semester. And I need to add those modules into the DB, when the submit button is pressed.

My problem is,
1. How do I store those selected modules temporarily until user will click on submit. (shall I store in JavaScript Array?)

2. If I have store them temporarily in JavaScript Array, how do I access those from PHP code to insert into the DB?

Please ask me, if I haven't described properly.

[Weedpacket]

It's easy for PHP to send information to Javascript - PHP just has to write the Javascript.

But the only method Javascript on the client has to communicate with PHP on the server is to have it submit a form with the information contained in it.

However you store the values in Javascript (an Array if you like), you'll need to put the final values into a hidden form field or fields, then have the Javascript function submit the form.

If you want to get funky with dynamic HTML, you could have the Javascript create hidden form field nodes and set their values.

But from a brief glimpse at your Javascript I'm guessing you're not (to tell you the truth, I'd hesitate). So instead you can just decide on some way of getting an array of data into a single string (say, running them together with a suitable separator character - "something|like|this|perhaps" - and have PHP sort it out again on the other end. Have a Javascript function do this (take the Javascript arrays and convert them into strings stored in hidden form fields) when the user chooses to submit the form.

[bhasheth]

Hello Weedpacket,
Thank you very much for letting me know about no possibility of sending infromation from JavaScript to PHP. I'm just a baby to all these tech... including JavaScript.

In my system, there is a possiblity of the user may keep check/uncheck the same module. So, I need to add it in my temporary store when added, and also need to delete it when unchecked. So, I don't see a luck in keeping the selected ones in the single string. Or may be I don't know how to do it.

Could you please explain me how do I do.

Would you mind a expalin me using some code.

Thanks a lot.

[bhasheth]

Hello Freinds,
Can anyone advise please.

Thanks a lot.

Bharti.

[Weedpacket]

Originally posted by bhasheth
In my system, there is a possiblity of the user may keep check/uncheck the same module. So, I need to add it in my temporary store when added, and also need to delete it when unchecked. So, I don't see a luck in keeping the selected ones in the single string.

That's not a problem; just use your temporary store to keep track of which modules they've checked, and only turn it into a string when they submit.

Don't ask me to code it - I always end up making a mess of my Javascript the first few tries 🙂

Hang on; I've just had a thought. The only things you need to store temporarily are the weights - and you're doing that. Tracking which modules are checked/unchecked is already being done - by the checkboxes. When they submit, checkboxes that have been checked will be sent back to PHP as part of the form submission. Reading through those will tell you which ones they were. If module 'Module1' isn't listed in the returned results (ie., $_POST['Module1'] is not set) then Module1's checkbox must have been unchecked when the user submitted the form.

[bhasheth]

Hello friends,

It is easy for me to write in HTML using php. But don't know how to read from HTML using PHP.

I haven't got clue that how my PHP will read the modules whose correspondance checkbox is selected at the time of submitting the form.

Please advise... Thanks once again.

[bhasheth]

Anyone around to advice please.... ??

[MrAlaska]

I always seem to make a fool out of myself by opening my mouth when I don't understand something, but I don't see why you need to involve javascript at all. Since this is a form that you are submitting to PHP and the calculations are based on what boxes are checked (do I have it right so far?) it seems it would make more sense to submit a simple form and let PHP crunch the numbers.

If you must do the calculations on the client side, I think you will need to write it back to the document before subitting it so PHP can get a handle on it. Or maybe that's what Weedpacket was saying. For instance. if you have a box that changes it's value dynamically you need to write back to the document into the value attribute of the checkbox, or do the hidden input thing already mentioned.

[mrmufin]

I'm responding to this as per your PM request, bhasheth. Unfortunately, the only thing that I can offer to your dilemma is... when using JavaScript for anything, anywhere, please consider what will happen if you user views the page with JavaScript disabled. I'm not a JavaScript-er, and frankly, I have very few nice thangs to say about it, other than it's fine for 'fluffy, fuzzy, cute and spiffy' toys, but I would never depend on it to do anything important.

Yeah, I know us folks who keep JavaScript disabled are in the small minority. But until such time as JavaScript-ers realize that there are many, many, many discrepencies amongst the 'supported capabilities' of JavaScript when run within different browsers on different platforms, I will keep JavaScript disabled about 90% of the time. I've been to far too many sites and waited eons for pages to load, only to have nothing displayed on my browser (even with JavaScript enabled, mind you) because that page was not tested using Netscrape 4.7x on Linux. Perhaps the page worked fine when using IE, or Netscrape 4.7x on Windoze; but the JavaScript functionalities supported on different OS's vary significantly.

I do not expect that every web designer in the world test their page using the same browsers and OS that I use; but I do expect that every web designer accept as fact that JavaScript functionalities vary significantly across OS's and browser versions, and accomodate (to at least some extent) those of us who choose to keep it disabled.

Back in the old days (oh, around 1997) there used to be a <script></noscript> tag that was encouraged when writing JavaScript for those of us who keep it disabled. Funny, I don't see that tagset used much anymore...

[MrAlaska]

Originally posted by mrmufin
Back in the old days (oh, around 1997) there used to be a <noscript></noscript> tag that was encouraged when writing JavaScript for those of us who keep it disabled. Funny, I don't see that tagset used much anymore...

The <noscript> tag enjoyed a brief flurry of popularity a couple years ago when people discovered they could disable the inserted advertisements on many free hosted sites, but I think the sites that survived went back to server side scripts.

I use javascript for the first layer of validation to take some load off the server, but I never depend on it. I believe a site must be fully functional in HTML firstmost and foremost.

My own browser does not allow any scripting, except the computer I use when developing. I get in trouble sometimes when I will send someone to a site and they complain about the pop-ups, sometimes I forget those things are even out there.

[Weedpacket]

Originally posted by bhasheth
It is easy for me to write in HTML using php. But don't know how to read from HTML using PHP.

For a full description on how to read the contents of form fields with PHP, see the manual in the section Variables from Outside PHP. But basically, to read the value of a checkbox when the form is submitted (remember: the form has to be submitted before PHP can read any of its fields): if the checkbox is named 'Module1', then if it is checked, isset($POST['Module1']) would be true, and if it's not, isset($POST['Module1']) would be false.