Spry JSONDataset and IE8 cross domain policy

Question

Hi,
I'm using Spry JSON Dataset to retreive feeds of JSON data from Google Picasa and then show the results on our photo page. Works fine in Firefox but not in IE8. Is this a cross domain issue or is something else happening to stop the page rendering the spry regions in IE8? I know IE8 can be quite fussy at times.
Debug tools in IE8 not the best (give me firebug any time)
Page is here www.thehmc.co.uk/photonew.html
Phil

Answer 1

Hi,
Now I've had time to play and got my head around what JSON-P really means - I've come up with a lightweight solution. Arnout thanks for your input as that sent me off on the right track.
I noticed that Google can provide the JSON string wrapped in a callback function - see format below
http://picasaweb.google.com/data/feed/api/user/thehmc.co.uk?kind=tag&alt=json-in-script&ca llback=testit&hl=en_GB
Firstly I define my Spry JSONDataset as before but don't give it an url to load the data from
var dsTags = new Spry.Data.JSONDataSet(null,{path:"feed.entry",  subPaths:["title","gphoto$weight"],sortOrderOnLoad: "ascending", sortOnLoad: "title.$t"} );
So introducing the function below, which dynamically adds a script to the document body pointing top the url you pass it
function makeRequest(sUrl) {
        var oScript = document.createElement("script");
        oScript.src = sUrl;
        oScript.async = true
        var done = false;
        oScript.onload = oScript.onreadystatechange = function()
            if ( !done && (!this.readyState || this.readyState === "loaded" || this.readyState === "complete") )
              done = true;
               oScript.onload = oScript.onreadystatechange = null;
               if ( oScript && oScript.parentNode )
                oScript.parentNode.removeChild( oScript );
        document.body.appendChild(oScript);
and then calling it, passing the url to the Google feed
makeRequest("http://picasaweb.google.com/data/feed/api/user/thehmc.co.uk?kind=tag&alt=json-in-script&ca llback=testit&hl=en_GB");
Function testit(root)
    dsTags.setDataFromDoc(root);
Since the JSON string is already converted to a JSON object when it arrives at the callback function I had to change the JSONDataset function as below to not to try and parse if already an object
Spry.Data.JSONDataSet.prototype.loadDataIntoDataSet = function(rawDataDoc)
    if (this.preparseFunc)
        rawDataDoc = this.preparseFunc(this, rawDataDoc);
    var jsonObj;
    if (typeof rawDataDoc == "object")
        jsonObj = rawDataDoc;
   else
        try    { jsonObj = this.useParser ? this.parseJSON(rawDataDoc) : eval("(" + rawDataDoc + ")"); }
        catch(e)
            Spry.Debug.reportError("Caught exception in JSONDataSet.loadDataIntoDataSet: " + e);
            jsonObj = {};
This works a treat in IE8 and Firefox.
I can see that your YQL version will be more flexible in terms of the number of feeds it'll be able to provide in JSON format but for now I just need this for Google Picasa.  Ideally I'd like a YQL version that retrieves the JSON string and then passes it to a user defined callback function to do with what it wants.
I need to change my other JSON datasets but otherwise the page will be good to go soon enough.
Cheers for your inputs
Phil