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PASSING
VARIABLES FROM HTML TO FLASH VIA QUERY STRING
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EXAMPLE
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You want to be able to use the same swf file on many pages to show different images. Obviously, you need to pass the image filename to Flash. What can you do? Since a filename is such a simple text, you can use query string to pass it. Assuming the image filename is image1.jpg, located at a folder named images. And assuming that the Flash movie will use a variable named imageFilename to refer to the file, then we can do this:
There you see that I appended a query string after the Flash movie filename (flaMovie1.swf). The query string contains one variable: imageFilename, with the value of images/image1.jpg. Note: The %2F is the url encoding for the "/" sign, and %2E is the url encoding for the "." sign. Since these symbols are unsafe or reserved, we should url encode them, although at the present Flash does not seem to care. So saying: imageFilename=images%2Fimage1%2Ejpg is essentially the same as saying imageFilename=images/image1.jpg. (see: Introduction to URL Encoding) In this way, when the Flash movie starts, that movie will have a variable named imageFilename within its _root or _level0. Then, I can say: loadMovie(_root.imageFilename); and it will load the specified image. Note: ActionScript 3 user should go here after reding this tutorial for Action Script 3 way of accessing query strings. Here are example of the swf file with different query string being passed:
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EXAMPLE
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Because you don't even know who the user will be, you cannot hard code the query string. That is, you cannot put: flashMovie.swf?userName=jim2000 in the html code since userName might be jane2 instead of jim2000. So, in this case, we must use another way to get the proper query string value. This requires being able to write the query string on the fly, as will be explored later. Let's first create a cookie. Enter a user name below then click the button. When the button is clicked, a cookie named "userName" will be created for you (JavaScript must be enabled for this example to work): Now that we have a cookie, let's see how we can get the cookie into Flash. Because Flash does not support cookie reading directly, we need to use a scripting language. I will show 2 examples. The first one uses ASP, the second one uses JavaScript, and the third one uses PHP. Using ASP Below is an example of using ASP to get the cookie value and pass the value to Flash.
Notice that I added lots of carriage returns (vbCrLf) so that the resulting code will be easier to debug. (Ie: when you open the page and view the page source, this prevents having everything written on a single line.). The When that code is run, the line " VALUE=""flaMovie2.swf?userName=" & _
Server.URLEncode(Request.Cookies("userName")) &""">"& vbCrLf & _
will be replaced with something like flaMovie2.swf?userName=john, assuming john is the userName stored in the cookie. The Server.URLEncode() function will make sure that the string is URL encoded, otherwise, if you enter something like "Jack & Joan", Flash will not interpret it correctly because the "&" sign is a special character. Click here to see the page generated by the script above. (Remember to set the cookie first using the form above, or the result will be undefined) You can do it more cleanly and efficiently with a code like below (even better, you should consider writing a function if you use the code often):
Using JavaScript With JavaScript, the process is similar. You can use document.write to pass the query string to Flash. You will need to write the entire OBJECT tag, since JavaScript is a client side scripting language, and you can't run a JavaScript code nested within an OBJECT tag. An example is shown below.
Note: Coding document.writes like above is very error prone and hard to debug because when you do View Source after opening the document, you don't see what the being written by the document.writes. Sometimes you forget to put a closing tag or a closing ">" and don't know why the page won't load. The easiest way for me to debug this kind of code is to use an older Netscape 4.8 browser. That older browser (at least the PC version) shows the result of document.writes when you do View Source. This is also why I appended the \n (start anew new line) often: to make it easier to see the result. Click here to see the page generated by the script above. (Remember to set the cookie first using the form above, or the result will be undefined). Note: The escape() function in getCookie() will make sure that the string is URL encoded, otherwise, if you enter something like "Jack & Joan", Flash will not interpret it correctly because "&" is a special character. Note however, that the escape() function does not encode '+' and '/' characters. For a workaround, see here. Using PHP
Or, using $HTTP_COOKIE_VARS[]:
When that code is run, the line $userName
(which is the same as
$HTTP_COOKIE_VARS["userName"]) will be
replaced with the userName stored in the
cookie. The urlencode() function encodes
the string to make sure that special characters in the
string are URL encoded. Without this, if the userName
contains special characters, such as the "&"
character in: John & Associates, then the result
will become unpredictable. Next, we will discuss how to pass HTTP query string (such as data from html forms) to Flash. |
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