Flex error 1034: Type Coercion Failed

Report · Jun 25, 2011

I extended the File class as AudioFile. I only added one new property "category". I intend to filter files out of a directory structure and keep the AudioFile objects in a simple indexed array. I also want to add category info to the AudioFile object's "category" property. The error is thrown after I call getDirectoryListing, assign the returned File objects to "content:Array", and then I iterate through "content" assinging each File object to an AudioFile object. I thought that sense AudioFile is an extension of File that this would not be a problem. The heart of the issue is how getDirectoryListing returns File objects but I need AudioFile objects. My next instinct is to override the getDirectoryListing method but I can not find the class declaration for File.

Is there a way to cast the File objects as AudioFile objects? Should I be using a different strategy for assigning category info to the File objects? Maybe I should not be extending File class at all. I am kind of stuck. Any help would be greatly appreciated.

Here is my code. Please note that this is my first flex/air/actionscript I ever wrote. I am using Flash Builder 4.5 and my target is Air Desktop. The extended class AudioFile is in AudioFile.as.

package
{
import flash.filesystem.File;

    public class AudioFile extends File
    {
        public function AudioFile()
        {
        }

        public var category:String;
    }
}

<?xml version="1.0" encoding="utf-8"?>
<s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009"
                        xmlns:s="library://ns.adobe.com/flex/spark"
                           xmlns:mx="library://ns.adobe.com/flex/mx"
                         xmlns:samples="samples.*"
                        applicationComplete="init()" width="386" height="581"
                        initialize="initData()">
    <s:layout>
        <s:VerticalLayout paddingTop="6" paddingLeft="6" paddingRight="6" paddingBottom="6"/>
    </s:layout>

    <fx:Script>
        <![CDATA[
            import AudioFile;

            import flash.events.Event;
            import flash.filesystem.File;

            import mx.collections.ArrayCollection;
            import mx.controls.Alert;

            private var audioObj:AudioFile = new AudioFile();

            protected function init():void
            {
// Center main AIR app window on the screen
                nativeWindow.x = (Capabilities.screenResolutionX - nativeWindow.width) / 2;
                nativeWindow.y = (Capabilities.screenResolutionY - nativeWindow.height) / 2;
                // Get notified when minimize/maximize occurs
                addEventListener(NativeWindowDisplayStateEvent.DISPLAY_STATE_CHANGING, onDisplayStateChange);
            }
// Handles when the app is minimized/maximized
            protected function onDisplayStateChange(e:NativeWindowDisplayStateEvent):void
            {
                trace("Display State Changed from " + e.beforeDisplayState + " to " + e.afterDisplayState);
            }

            private var masterList:ArrayCollection = new ArrayCollection();
            private var dgArray:Array = new Array();

            [Bindable]
            private var initDG:ArrayCollection;

            public function initData():void {
                var initDG:ArrayCollection = new ArrayCollection(dgArray);
            }

            private function analyze():void {
                // ActionScript file

                var sourceDir:AudioFile = getSourceDir();
                var fileList:Array = new Array();
                var dirList:Array = new Array();

                function transverseDirStructure(sourceDir:AudioFile):Array {
                    var flag:Boolean = false;
                    var dirList:Array = new Array();
                    var fileList:Array = new Array();

                    do {
                        var contents:Array = sourceDir.getDirectoryListing();

                        for(var i:int=0;i < contents.length; i++) {
                            // test for isDirectory
                            var file:AudioFile = contents;
                            if (file.isDirectory == true) {
                                dirList.push(file);
                            }
                            else {
                                fileList.push(file);
                            }
                        }

                        if (dirList.length == 0)
                            flag = false;
                        else {
                            // recursion
                            fileList = fileList.concat(transverseDirStructure(dirList,fileList));
                        }
                    } while (flag == false)

                    return fileList;
                }

                function filterExtensions(fileList:Array):Array {
                    var cleanExtensionsList:Array = new Array();
                    for each (var i:AudioFile in fileList) {
                        if (i.extension == ".wav" || ".aiff") {
                            cleanExtensionsList.push(i);
                        }
                    }

                    return cleanExtensionsList;
                }

                function filterSize(fileList:Array):Array {
                    var cleanSizeList:Array = new Array();
                    var maxFileSize:int = 350000;
                    for each (var i:AudioFile in fileList) {
                        if (i.size < maxFileSize) {
                            cleanSizeList.push(i);
                        }
                    }

                    return cleanSizeList;
                }

                function categorizeAudioFiles(fileList:Array):Array {
                    var masterList:Array = new Array();

                    var flag:Boolean = true;

                    var categories:Array = new Array();
                    categories.push("kick","snare","hat","crash","clap");

                    for each (var i:AudioFile in fileList) {
                        for each (var x:String in categories) {
                            if (i.name.search(x) > 0) {
                                // Add name of category to the extended property.
                                i.category = x;
                                masterList.push(i);
                            }
                        }
                    }

                    return masterList;
                }

                fileList = transverseDirStructure(fileList);
                fileList = filterSize(fileList);
                fileList = filterExtensions(fileList);
                fileList = categorizeAudioFiles(fileList);
            }



            private function generateRandom():void {

            }

            private function setDestination():void {
                var file:AudioFile = new AudioFile();
                file.addEventListener(Event.SELECT, dirSelected);
                file.browseForDirectory("Select a directory");
                function dirSelected(e:Event):void {
                    txtDestination.text = file.nativePath;
                }
            }

            private function getDestination():AudioFile {
                var destinationDir:AudioFile = new AudioFile();
                destinationDir.nativePath = txtDestination.text;

                return destinationDir;
            }

            private function getSourceDir():AudioFile {
                var sourceDir:AudioFile = new AudioFile();
                sourceDir.nativePath = txtBrowse1.text;

                return sourceDir;
            }

            private function setSourceDir():void {
                var file:AudioFile = new AudioFile();
                file.addEventListener(Event.SELECT, dirSelected);
                file.browseForDirectory("Select a directory");
                function dirSelected(e:Event):void {
                    txtBrowse1.text = file.nativePath;
                }
            }

            // Control logic

        ]]>
    </fx:Script>

    <mx:Form width="373" height="113" id="formChooseDirectory1">
        <mx:FormHeading label="1. Choose A Source Directory..." width="315" fontSize="13" fontFamily="Verdana" color="#CF71FF"/>
        <s:Button label="Browse..." fontFamily="Verdana" fontSize="13" color="#CF71FF" id="btnBrowse1" enabled="true" click="setSourceDir()"/>
        <s:TextInput width="333" id="txtBrowse1" enabled="false" text="C:\Users\RokaMic\Bangin Beats"/>
    </mx:Form>
    <mx:Form width="373" height="231" id="formAnalyze">
        <mx:FormHeading label="2. Analyze Samples..." fontFamily="Verdana" fontSize="13" color="#00D8FF" width="245"/>
        <s:Button label="Analyze" fontFamily="Verdana" color="#00D8FF" id="btnAnalyze" enabled="true" click="analyze()"/>
        <mx:DataGrid editable="false" enabled="true" fontFamily="Verdana" color="#00D8FF" width="337" dataProvider="{initDG}">
            <mx:columns>
                <mx:DataGridColumn headerText="File name" dataField="filename" color="#00D8FF" fontFamily="Verdana"/>
                <mx:DataGridColumn headerText="Category" dataField="category" color="#00D8FF" fontFamily="Verdana"/>
            </mx:columns>
        </mx:DataGrid>
    </mx:Form>
    <mx:Form width="374" height="173" id="formGenerate">
        <s:Button label="Generate Drum Kits" width="342" height="52" fontSize="18" fontFamily="Verdana" color="#00FF06" id="btnGenerate1" enabled="true" click="generateRandom()"/>
        <mx:FormItem label="How Many?" fontFamily="Verdana" fontSize="13" color="#00FF00" width="340">
            <s:HSlider width="206" stepSize="1" value="1" minimum="1" maximum="25" id="sliderHowMany" liveDragging="true"/>
        </mx:FormItem>
        <s:Button label="Destination..." color="#00FF00" id="btnDestination" enabled="true" click="setDestination()"/>
        <s:TextInput width="332" id="txtDestination" enabled="false"/>
    </mx:Form>
</s:WindowedApplication>

Report · Jun 25, 2011

which line of code triggers the error. and what's the complete error?

Report · Jun 25, 2011

The error is triggered here:

fileList = transverseDirStructure(fileList);

I think the lines in question are: (inside the transverseDirStructure function)

do {
                        var contents:Array = sourceDir.getDirectoryListing();

                        for(var i:int=0;i < contents.length; i++) {
                            // test for isDirectory
                            var file:AudioFile = contents; <----- I think this is the problem. contents returns a File object
                            if (file.isDirectory == true) {
                                dirList.push(file);
                            }
                            else {
                                fileList.push(file);
                            }
                        }

The complete error message is: (from Flash Builder 4.5 debug mode)

TypeError: Error #1034: Type Coercion failed: cannot convert []@921f101 to AudioFile.
at DrumKitGenerator/analyze()
at DrumKitGenerator/__btnAnalyze_click()

Line 129 is the call to the transverseDirStructure function.

Report · Jun 25, 2011

is transverseDirStructure() returning an AudioFile instance?

if yes, this is probably something asynchronous occuring in transverseDirStructure().

(and, is transverseDirStructure supposed to be traverseDirStructure?)

Report · Jun 25, 2011

yes transverseDirStructure is supposed to be traverseDirStructure. I thought someone might call me on that. thank you

Report · Jun 25, 2011

a name is just a name. but traverse sounds like an asynchronous operation.

Report · Jun 25, 2011

transverseDirStructure() is returning a indexed array of AudioFile objects.

I think the problem is when I call

var contents:Array = sourceDir.getDirectoryListing();

getDirectoryListing() returns File objects. At this point I need to iterate through the contents:Array. Using the a for loop I pull each File object out of the array and try to assign them to a AudioFile object. I suspect this is what triggers the Type coercion error.

I could simply not use the AudioFile object until later but I will run into the same error eventually. Or I may need to use a different strategy than extending the File class with addition of my own custom property.

Report · Jun 25, 2011

you know what I just thought of this. I probably could just use the nativePath property of the File object and create a new AudioFile object.

What I was orginally trying to do was this:

class File { ... }

class AudioFile extends File {

var category:String;

}

var fileObj:File = new File(url);

var audioObj:AudioFile = new AudioFile();

audioObj = fileObj; // File Coercion error!

Instead maybe I could do this:

var fileObj:File = new File(url);

var audioObj:AudioFile = new AudioFile(fileObj.nativepath);

Report · Jun 25, 2011

the flash compiler will tell you exact line of code causing the problem. you've mentioned 2 different lines of code and that makes it sound like you don't know which line of code is causing the problem.

Report · Jun 25, 2011

The error occurs on line 129, which is as follows:

fileList = transverseDirStructure(fileList);

The compiler is only telling me that the error is occuring on line 129.

here is the error message:

TypeError: Error #1034: Type Coercion failed: cannot convert []@921f101 to AudioFile.
at DrumKitGenerator/analyze()
at DrumKitGenerator/__btnAnalyze_click()

Report · Jun 25, 2011

i copied this from your code:

does that contain line 129? if so, where are those last 5 lines?

they don't appear to be part of the categorizeAudioFiles() function so there should be a compiler error about that last }. or, you've nested a named function somewhere.

Report · Jun 25, 2011

I see whats wrong now.

I was calling transverseDirStructure() with an array as an arguement like so:

filename = transverseDirStructure(filename);

But I had defined the function with a File object as the arguement, like:

function transverseDirStructure(sourceDir:File):Array { ... }

So i was tring to pass the function an array but what it needs is a File object.

Serious NOOB mistake.

Sorry to have wasted your time. And I thank you very kindly.

On a sidenote:

previously you had mentioned that I named the function as if it my asynchronous. Could you explain about that naming convention a little bit?

Report · Jun 25, 2011

traversing a directory structure sounds like you're going to iterate through everything in the directory. if you encounter another (sub)directory, i imagined you were going to iterate through everything in that (sub)directory etc. so, you could end up not being able to use a return statement correctly. i gather that's not the problem so you don't need to deal with that issue.

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Flex error 1034: Type Coercion Failed

1 Correct answer