Josh Talks Flash

Wow. Very slick. I can’t wait to give that a go. Thanks for the heads up.

[...] you haven’t read my first post about filtering data with E4X, go check it out now. Today, I’ll expand on it to add a few more options that you have at your [...]

Excellent piece, a huge help. A question: are there any filters that allow filtering by START of a string, as in all books whose authorName starts with “C”?

Thanks.

[...] Labs posted two great articles on starting out with E4X in AS3.  The first is how to filter data using E4X and the second is a follow up with more advanced techniques.  Really great stuff.  XML is [...]

Devon, I filtered two fields just like that in the example above where I wanted items from Amazon for less than $400. I assume you’re responding to my last example, where I use a loop to handle multiple filters. That example is for the case where you don’t know how many different fields you’re filtering by until runtime. The user might choose the specific filters needed similar to how smart playlists work in iTunes. There could be two, three, or any number of filters. In that case, it’s impossible to use straight E4X because you don’t know the exact filters needed until the user picks them.

Duane,

I can’t give you a definitive answer on that one, as I don’t work with RemoteObjects or CF. If your current returned data is an instance of the XML class (which is what is used by E4X), then you should be fine. If it’s a String as far as ActionScript is concerned, then you’re probably going to have to set a result format or do the conversion manually.

Neat. That’s going to sound funny, but I hadn’t realized one could filter on sometimes missing attributes within E4X:

xmlList.(@attr == "2") will throw an exception if any of the children of xmlList doesn’t have an attribute “attr” present.
However, xmlList.(attribute("attr")==2") works just fine.
I wish I had thought of that 6 months ago.

Also, your last example can be rewritten as

var filtered:XMLList = data.item;
var fields:Array = [{name: "source", value: "Amazon"}, {name: "price", value: "599.99"}];
filtered = filtered.(fields.every(function(item:*,index:int,array:Array):Boolean {
    return child(item.name) == item.value;
}));

Technically, it’s one E4X expression, although it doesn’t exactly improve the code maintainability.

Your last example, filtering when you don’t know if an attribute exists – here’s the E4X solution:

var filtered:XMLList = data..item.(
    hasOwnProperty("@source") &&
    @source == "Amazon" &&
    hasOwnProperty("@price") &&
    @price == "599.99");

From Essential Actionscript 3.0:

To filter a list where not every item has a given attribute or child element, we must use hasOwnProperty( ) to check for the existence of that attribute or child before filtering on it. Otherwise, a reference error occurs. For example, the following code returns every element in someDocument that has a color attribute set to “red”:

someDocument..*.(hasOwnProperty("@color") && @color == "red")

Josh,

cool summary. E4X is one great beast, that´s true.something that is also worth noting is that you don´t have to format the xml when you generate it within your class, it will be done automatically, so there´s no need anymore for “ignore whitespace2 or what it was called again. that´s also very nice when outputting the xml to a server side PHP script to save it to disk, the xml file you´ll get is very well structured and perfectly readable, not like the old times where you had just a huge pile of code…

anyways, just something.

best

mathias

It is very helping example. I have some problem to filter data in XMLList. I want to show the elements of the XMLList in tree control. But I don’t want to show the leave nodes.
May any one help in that problem?

Thanks

I found a problem in using the same syntax:
var items:XMLList = data.item.(source == “Amazon” && price <400);

into a binding expression like

dataProvider=”{data.item.(source == “Amazon” && price <400)}

it will not accept the &&

Any idea – apart from doing it in AS?

Hi,
thanks for a great and utterly useful post!
I do have a problem though; any idea if it’s possible to add elements together and compare them to a variable within the parantheses?

Like this for example:
XMLList.(available == “Yes” && (from_price + from_tax + from_postage) >= minCost && (to_price + to_tax + to_postage) <= maxCost).@ID;

Hi Josh,

In your example, how would you filter an item that contains the number 3 in it’s name so that your results would return Playstation 3 and X-box 360? Thanks for your posts and your help.

You deal with clean XML feed here, but i like em dirty.

I keep getting the error -
Error #1009: Cannot access a property or method of a null object reference.
-because not all my nodes have the attribute ‘contactname’ so i need to check if that attribute is apparent before trying to add it to my array.

[...] Ways to Use EX4 To filter XML Data in ActionScript 3 (Thanks to: Josh Tynjala at Josh Talks Flash) [...]

mr.moses, with two source elements, the following seems to work for me:

data.item.(source.contains("Target"))

I didn’t know about the contains() method until today, so thanks for the great question.

Matt Long, it should be possible. How easy it will be depends on how the date is formatted in the XML, though. The Date constructor with one argument or Date.parse() could be useful for extracting date values for comparison.

Daniel, you might be able to loop through the parent elements and use setChildren("") to remove the children.

1

2

Thanks a lot. Think this will solve problems!

[...] There are a few nice posts about E4X filters on this blog: http://joshblog.net/2007/05/08/methods-to-filter-data-with-e4x-in-flash-9/ [...]

trying to figure out how to sort if an item has more than one of the same node type…

such as:

<item name="Consoles">
<source> PS3 </source>
<source> PS2 </source>
</item>

if I searched for all items with PS2 this would be skipped with the methods used above…

Hey, great article, but I’ve run into a snag with your last example. I cut and pasted your code and get this in my output window:

(your code and your xml file which I swear I did not change)

var filtered:XMLList = data.item;
var fields:Array = [{name: "source", value: "Amazon"}, {name: "price", value: "599.99"}];
       
var fieldCount:int = fields.length;
for(var i:int = 0; i <fieldCount; i++)
{
    var fieldName:String = fields[i].name;
    var fieldValue:String = fields[i].value;
    filtered = filtered.(child(fieldName) == fieldValue);
	trace(filtered);
}

this code is supposed to return Amazon items worth 599.99, however it returns 3 Amazon items. It's returning 2-599.99 items and 1-399.99 item which is not what's in the xml file.

output results

Amazon
399.99

Amazon
599.99

Amazon
599.99

I’m new to xml and AS3 so I wanted to make sure this wasn’t happening because I’m using Flash CS4 (since your original post is almost 3 years old)

Thanks Josh, that was it and I should have tried it. I only had intro classes to Flash MX2004 and that’s been almost 3 years ago. Kinda rusty.

Great post, I was able to use a couple of scripts above but ran into an issue and was wondering if anyone had some insight:

I have some data that I separated into labels of a combobox:

—
Features3
Features1,Features2,Features3
Features2,Features3
Features1
—-
if (featuresCombo.selectedLabel != item.FEATURES)
return false;

return true;
—-

If you select ‘Features3′ for example it doesn’t return the selections that have multiple entries separated by commas.

Is there a way to filter based on the occurance of a string rather than matching the whole string?

I tried to use the (contains) function from above and was getting this error:Error #1123: Filter operator not supported on type mx.utils.ObjectProxy.

Thanks for any help.
-Auzzie