Question

Is there an existing class in Flash or Flex that gets the value from an object from it’s property chain?

For example, something like this:

private function labelFunction(item:Object, column:GridColumn):String {
     // where dataField equals "fields.status.name"
     var value:String = PropertyChain.getValue(field, column.dataField);
     return value;
}

~~~ Update ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I found this private method in the Binding class as well that could probably be used in a custom class:

/**
 *  @private
 */
private static function getFirstWord(destStr:String):String
{
    // indexPeriod and indexBracket will be equal only if they
    // both are -1.
    var indexPeriod:int = destStr.indexOf(".");
    var indexBracket:int = destStr.indexOf("[");
    if (indexPeriod == indexBracket)
        return destStr;

    // Get the characters leading up to the first period or
    // bracket.
    var minIndex:int = Math.min(indexPeriod, indexBracket);
    if (minIndex == -1)
        minIndex = Math.max(indexPeriod, indexBracket);

    return destStr.substr(0, minIndex);
}

Answer 1

I don’t think there’s an existing function. But it’s very easy to build one, and it need not be restricted to generic Object sources, as any member of any object can be retrieved by name using square bracket notation. This simple version doesn’t do any validation:

public static function getByName(root:*, member:String):* {
    var memlist:Array = member.split('.');
    var temp:* = root;
    for(var i:uint = 0; i < memlist.length; i++)
        temp = temp[memlist[i]];
    return temp;
}

// And you can use this even on strongly-typed values, such as a MovieClip:
trace("stageWidth =", SomeUtil.getByName(mc, "stage.stageWidth"));