How to test if a file exists ?

Ze-Palm · 10/18/2009, 05:22 AM

Hi all,

In my app, i parse a parameter from Scene1 to Scene2.

This parameter is correctly declared In Scene2.
Here is the code of Scene2:

Code:

function Scene2Assistant(param) {
this.param1 = param;
}

This parameter is used to display a picture in Scene2 when Scene2 is activated

Here is the code :

Code:

Scene2Assistant.prototype.activate = function(event) {
	this.myCountryDivElement.mojo.manualSize('320','350');
	this.myCountryDivElement.mojo.centerUrlProvided('images/'+ this.param1 +'.jpg');
}

All works fine when an image file corresponding to the parameter exists.

what i want to do is to check if the file corresponding to the parameter parsed exists.
If Yes, then the value of this.param1 is take into account
If No, then i want to set a default value.

Is this test must be coded in protoype.setup as below ?

Code:

Scene2Assistant.prototype.setup = function() {
	var file = Mojo.appPath + 'images/' + this.param1+'.jpg'
             ...................
             ..................

I browse the forum but not find something relevant.
What is the code to do it ?

Thanks for your help.

Ze-Palm · 10/18/2009, 11:52 PM

Up ! Anyone ?

Ze-Palm · 10/20/2009, 01:58 PM

I tried a lot of syntaxes, read guidelines, ... but not fixed my problem.

In this large and friendly community, is there a guru to help me ?

Any help would be really appreciated.

PreGame · 10/20/2009, 06:28 PM

you would have to use one of palm's API's to do that. You can TRY to do an Ajax.Request('/path/to/file',...); to see if it returns data. But other than that javascript cannot really open files without the use of activex.

Ze-Palm · 10/22/2009, 01:35 AM

Thanks PreGame.
Ajax.Request function seems to be the solution

First of all, i try to display the path but am having trouble to figure out.

Code:

var url = Mojo.appPath + 'images/' + this.param1;
this.showDialogBox('Path', url);

In which section of the scene the test must be coded ?
I tried in prototype.setup and prototype.activate but it don't work.

Any help ?

Ze-Palm · 11/05/2009, 09:50 AM

Ajax.Request is the solution. Thanks PreGame

Here is the code for whom who are interested in:

Considering that :
this.param1 is an argument parsed from Scene1
This code is to test if a jpg file exists in the app path.

Code:

var file = Mojo.appPath + this.param1 +'.jpg';
	var request = new Ajax.Request(file, {
        	method: "get",
        	onSuccess: this.OnSuccess.bind(this),
        	onFailure: this.OnFailure.bind(this)
    	});

If the file exists then the correct jpg is displayed

Code:

Scene2Assistant.prototype.OnSuccess = function(transport){
	this.myCountryDivElement.mojo.centerUrlProvided(this.param1 +'.jpg');
};

If the file not exists then a default jpg is displayed

Code:

Scene2Assistant.prototype.OnFailure = function(transport){
	this.myCountryDivElement.mojo.centerUrlProvided('Map-Demo.jpg');
};

Hope this helps