How does one access the properties of a Javascript object in Silverlight?

Question

I am accessing a Javascript object (which has a form similar to this: { 1 : "Option 1", 2 : "Option 2", 3 : "Option 3" }) from Silverlight using code similar to the following:

dynamic window = HtmlPage.Window;
var options = window.GlobalObject.getDropdownItems();

Now, the problem is that options is now of type ScriptObject. This wouldn't be a problem if I knew what the names of the properties of my Javascript object were (I could just do options.GetProperty(1) to get the label for the first option). However, this won't work because I need both the values and the names of the options. Is there some way to convert it to a Dictionary<int, string> or something similar?

Joe McBride · Accepted Answer · 2010-11-05 05:51:12Z

Are you able to change the input of the options? If you are, this is what I would suggest.

Change the input of the values to something along these lines:

function getDropdownItems() {
    var items = [{ Value: 1, Name: "Option 1" }, { Value: 2, Name: "Option 2" }, { Value: 3, Name: "Option 3"}];
    return items;
}

Then in Silverlight you can easily convert it to a typed object.

public class Option
{
    public int Value { get; set; }
    public string Name { get; set; }
}

private void LoadOptions()
{
    dynamic window = HtmlPage.Window;
    var dynamicoptions = window.getDropdownItems();

    ScriptObject scriptObject = dynamicoptions as ScriptObject;

    if (scriptObject != null)
    {
        var options = scriptObject.ConvertTo<Option[]>();
        if (options != null)
        {
        }
    }
}

I've found this is the easiest way to work with javascript objects.

Steven Oxley · Accepted Answer · 2010-11-05 16:24:50Z

This is how I solved the problem. First of all, I added a Javascript function called getKeysOfObject, which looks like this:

var getKeysOfObject = function (o)
{
    var keys = [], i;
    for (i in o) {
        keys.push(i);
    }
    return keys;
}

Then I used that function to determine what the keys of my object were. From there, it wasn't too difficult to get the information I needed from the object.

dynamic window = HtmlPage.Window;
dynamic options = window.getDropDownItems();
dynamic keys = window.getKeysOfObject(options);
int numKeys = Convert.ToInt32((double)keys.length);

for (int i = 0; i < numKeys; ++i)
{
    if (options[keys[i]].GetType() == typeof(ScriptObject))
    {
        optionDictionary.Add(new KeyValuePair<int, string>(
            Convert.ToInt32((string)keys[i]),
            (string)options[keys[i]]);
    }
}

The reason for checking the type of the actual property of the object is that silverlight was adding a weird $__slid property to the object.

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