From: mario <ddss@...>
Date: 2008-05-20T02:00:03+09:00
Subject: Re: CGI and checkboxes

I love your example and your sense of humor.
I actually printed it.
I just moved to Ruby from PHP and I got to say... What a difference in
the coding!!


On Tue, 15 Jul 2003 07:23:58 +0900, "Mark J. Reed"
<markjreed@mail.com> wrote:

>On Tue, Jul 15, 2003 at 06:55:12AM +0900, Kurt M. Dresner wrote:
>> How do I get the value from a checkbox made with cgi.checkbox ?
>> 
>> I need to make a decision based on whether or not the checkbox is
>> checked - will that be sent to me as a parameter?
>
>You might want to invest in an introductory book on CGI programming.
>The language doesn't matter, since you're looking for the mechanisms, not the
>syntax, but the Perl/CGI book would be a good choice since Ruby's 'cgi' module
>is based on Perl's CGI.pm.  
>
>In any case, it sounds like there's some confusion about the sequence
>of events, possibly because of the wide range of functions in the
>cgi module.
>
>Your basic web browser/server interaction works like this:
>
>1. Browser sends request to some web server for some page.
>
>2. Server sends requested page to the browser.  This time it 
>   happens to be HTML containing a <form>.
>
>	Sometimes this page is generated dynamically by a CGI (or Java
>	servlet or JavaServerPage or ActiveServerPage or PHP page
>	or whatever), but it can be a plain old static HTML file
>	if the form itself doesn't change.
>
>3. Browser renders form for the user's benefit.
>
>4. User fills out the form and clicks the submit button.
>
>5. Browser sends a new request to some web server (possibly a different
>   web server) for some page (possibly a different page, even if it's on
>   the same server as before).  (The page requested is determined by
>   the value of the "action" attribute in the HTML <form> tag; this is how
>   you can have a static form that results in a CGI being invoked when it's
>   submitted.)  The request includes data about the way the user filled out
>   the form.
>
>6. The server sends the results of the submittal back to the browser.
>   Usually this is another HTML page, but it could be an image, or
>   XML that the browser needs to transform with a stylesheet, 
>   or plain text, or whatever.
>
>7. The browser displays results
>
>For this to be useful, the page requested by the browser to the
>server in step 5 - which is the one specified by the action attribute
>of the <form> tag - is usually to some sort of dynamic page: CGI,
>Java servlet, JSP, ASP, etc.  That way the page sent back to the browser
>in step 6 can depend upon the contents of the form.  (It is possible, however,
>request a staitic page containing some JavaScript; then when displaying the
>results in step 7 the browser might execute some JavaScript code that changes
>what's displayed based on the data submitted.  You could also skip
>the round trip to the server entirely by just having a button that invokes
>some JavaScript in the browser that does something based on the contents
>of the form.  But I digress.)
>
>The data submitted to the server in step 5 is a sequence of (name,
>value) pairs.  If you don't specify a method attribute on the <form>
>tag, or specify it as "GET", then you can see these name=value
>pairs at the end of the URL requested in step 6.  Something like
>http://myserver/cgi-bin/myCgi?name1=value1&name2=value2&name2=value2
>(name2 has more than one value in this case), etc.  Different types
>of <input> tags fill these out differently, but in all cases,
>the name and value are just strings:
>
>	For a text input, the value is the typed in text.
>
>	For most other inputs, there is a value="" attribute in the HTML
>	which tells the browser what to send when that option is selected.
>	This includes the <option>s within a <select> (whose values can be
>	different from the strings shown to the user, like this:
>
>		<strong>Country:</strong>
>		<select name="country">
>	 	<option value="jp">Japan</option>
>	 	<option value="us">United Kingdom</option>
>	 	<option value="uk">United States</option>
>		</select>
>
>	It also includes buttons, radio buttons, and checkboxes.
>	In these cases, the paramter given by the name="" is not
>	sent at all unless the element is clicked.
>
>	For instance:
>
>		<input type="checkbox" name="spamMe" value="yes" 
>		       checked="checked" /> Send me email!
>
>	If the user leaves that box checked, then the CGI will see
>	an input parameter named "spamMe" whose value is "yes".
>	If the user unchecks it, then the CGI will not see any input
>	parameter of that name.  The code to check looks something
>	like this:
>
>		require 'cgi';
>		q = CGI.new;
>		.
>		.
>		.
>		if q['spamMe'].length > 0 then
>		    # check box was checked
>		    spamTheHeckOutOf(q['email_address'][0])
>		else
>		    # check box wasn't checked
>		    spamTheHeckOutOfThemAnyway(q['email_address'][0])
>		end
>	   
>-Mark