19.0. Introduction There are many reasons why you may want to send and load values from and to your Flash movies, including to: Send form values to a server-side script to store in a database. Send values from an email form to a server-side script to send the email. Load values from a text file (appropriate when the values are subject to change, such as for the current weather or for a links page). Load values from a server-side script where the values are drawn from a database, such as categories in an e-commerce application. Send values to a server-side script for processing, and return a value to the Flash movie, such as for a login process.
When loading data from a URL, the Flash Player interprets the data in one of three possible ways: as text, raw binary data, or URL-encoded variables. URL-encoded variables follow these rules: Each variable name is associated with a value using an equals sign, without spaces on either side of the equals sign. Variable values loaded into Flash movies are always treated as strings; therefore, you should not enclose any values in quotes, as you would within ActionScript. A proper example of this is artist=Picasso. When there is more than one name/value pair, each pair is separated by an ampersandfor example, artist=Picasso&type=painting. Spaces within the values should be replaced by plus signs (+), not %20, as in: title=The+Old+Guitarist. (Spaces and %20 may also work, but stick with plus signs for the greatest compatibility.) Any character that is not a digit, a Latin 1 letter (non-accented), or a space should be converted to the hexadecimal escape sequence. For example, the value "L'Atelier" should be encoded as L%27Atelier (%27 is the escape sequence for an apostrophe). See Table 19-1 for a list of common escape sequences.
Table 19-1. Common URL-encoded escape sequences| Character | Escape sequence | Character | Escape sequence |
|---|
<space>
| %20 or + | .
| %2E | !
| %21 | /
| %2F | "
| %22 | :
| %3A
| #
| %23 | ;
| %3B
| $
| %24 | <
| %3C
| %
| %25 | =
| %3D
| &
| %26 | >
| %3E
| '
| %27 | ?
| %3F
| (
| %28 | @
| %40
| )
| %29 | |
| %7C
| *
| %2A | ~
| %7E
| +
| %2B | \
| %5C
| ,
| %2C | ^
| %5E
| -
| %2D | _
| %5F
|
Here is an example of variables in URL-encoded format: artist=Picasso&type=painting&title=Guernica&room=L%27Atelier
Sending and loading data has changed dramatically in ActionScript 3.0. The LoadVars class has been removed and replaced with a more robust URLLoader class in the flash.net package. URLLoader is supported by a new cast of characters, namely URLRequest, URLVariables, and URLStream (and a few others). These classes combine to form a rich API that offers more functionality and flexibility than what was available in previous versions. Something that has not changed, however, is that loading data into the Flash Player is still subject to the standard security sandbox. That is, you can load from a file or script only if it is within the same domain that the movie is served from. For ways around the domain security limitation, see Recipe 3.12. |
