Checking if a variable has been loaded

1

hello all,

can i check whether an external file exists?

i’m using this code to get the data from a file:

loadVariables(fileName.txt, outputBox); //outputBox is the instance name of the text box

i’m not loadig any variables as such, but dumping the text in the file straight into the textbox

now i want to check if fileName exists

cheers

2

Yup, using LoadVars, rather than loadVariables, assuming u got MX Version:

loadHandler = new LoadVars();
loadHandler.onLoad = function(success){
if(success){
myTextBox.text = loadHandler.ExternalVariable;
} else {
myTextBox.text = "Text file not existed";
}
}
loadHandler.load("textfile.txt");

Hope this helps.

yours,
h88

3

cheers h88! i couldn’t get that code working (do i need a php/mySql enabled server?)

i got the thing ‘working’ with the loadVariables anyway! (just a minor snag):

the following code works fine on my PC, but when the swf is uploaded (slower) “no data” shows on the textbox for a second or so before the file loads, so i could do with a loop to waste some time while the file loads…

frame1
loadVariables(“myFile.txt”, this);

frame2
if (this.update){
update=update; //the output txtbox shows ‘update’ var
stop();
} else{
update = “no data”
}
stop();

i’m having trouble understanding what (this.update) actually is?

is it checking if the vaiable in the text file has loaded? or is it checking if there’s anything in the textbox that has the ‘variable’ update assigned to it?

PS i’ve uploaded the fla incase i’m making no sense and anybody would like to see the fla - but just a pointer would be fine

thanks, and sorry to be bringing this up again! :x

4

*Originally posted by j0se *
**frame1
1> loadVariables(“myFile.txt”, this);

frame2
2> if (this.update){
3> update=update; //the output txtbox shows ‘update’ var
4> stop();
5> } else{
6> update = “no data”
7> }
8> stop();
**

Hiya.

First off, this is what is happening, line by line, with the code above:

Frame1
Line1: If this code is attached to the textbox, then the contents of myFile are loaded into it.

Frame2
Line2: This basically says, “If the local variable ‘update’ that is contained in this textbox instance (I assume again this code is attached to the textbox instance) contains ANYTHING AT ALL, then…” If you haven’t initialized the variable “update”, then it may have some garbage in it, which means this if statement will be true.

Line3: This line does nothing. It’s like saying 5 = 5. Flash already knows that a variable equals itself.

Line4: This line stops the timeline from playing, but not the code from continuing. This is redundant since you have a stop at line 8 anyway.

Line6: This sets ‘update’ to “no data”, which I assume is what appears in the textbox.

Now, that was all just to help you follow along what was going on, since you said you didn’t know what the this.update was all about. You said the box shows “no data” for a bit, then the myFile text pops up in it, right? Well, it seems what’s happening is the first frame starts loading up myFile (this takes a while, but the animation continues regardless). In frame 2, while myFile is still loading, this.update is seen to be empty (thus the IF statement is false, so the ELSE block is executed). The ELSE block puts “no data” into the textbox, and the animation stops. Meanwhile, myFile is STILL LOADING. LoadVariables (and loadVars too) is an asynchronous action, which, to my understanding, means the code will continue to be executed, without waiting for loadVariables to finish executing (in other words, the variables are loaded while other stuff goes on).

Basically, this means that all you have to do is replace your code above with the following (which will accomplish the exact same thing):


Frame 1:
update = "no data";
loadVariables("myFile.txt", this);
stop();

That’s it. Obviously this doesn’t do what you wanted to originally accomplish, which was, IIRC, to check whether an external file exists. The only way I know of doing that is by using the loadVars object, new to Flash MX. If you have MX, use the getBytesTotal() method of the loadVars object. getBytesTotal() returns “undefined” if it doesn’t/can’t load the target file. So you could check if the total bytes of the file is defined or not, and if it is, you know the file exists.

Sorry about the long-winded explanation, but I’m at work and I’m bored. :stuck_out_tongue:

Hope that helps!

-Al

5

cheers for the long reply :slight_smile: - i needed a walk-through!

i was confused by the use of ‘this’ - i just couldn’t mentally see how it was attatched to any particular object

many thanks

h88: i got the loadVars working also (ignore my php question)
:slight_smile: