CRM 2011: Jscript to Read Optionset selected text using Metadata service

Hi,
Recently I was working on an assignment where I had to retrieve data of a lookup record using Jscript, I accomplished to retrieve the lookup record's data using RestFul services. But I found that for the optionset field on the lookup record, i got back only the value (integer) of the selected option, whereas i was expecting to get both, value as well as its text. only later i found that to retrieve its text, I had to do a soap request to the organization metadata service.
Here;s the code which will get the optionset's text. You need to supply the entity logical name, attribute logical name & its selected value, to get back the text of selection option.

function RetrieveAttributeSync(EntityLogicalName, LogicalName, MetadataId, RetrieveAsIfPublished, attributeValue) {

    var ODataPath;
    var serverUrl = Xrm.Page.context.getServerUrl();
    ODataPath = serverUrl + "/XRMServices/2011/Organization.svc/web";

    var request = "<Execute xmlns=\"http://schemas.microsoft.com/xrm/2011/Contracts/Services\" xmlns:i=\"http://www.w3.org/2001/XMLSchema-instance\">";
    request += "<request i:type=\"a:RetrieveAttributeRequest\" xmlns:a=\"http://schemas.microsoft.com/xrm/2011/Contracts\">";
    request += "<a:Parameters xmlns:b=\"http://schemas.datacontract.org/2004/07/System.Collections.Generic\">";
    request += "<a:KeyValuePairOfstringanyType>";
    request += "<b:key>EntityLogicalName</b:key>";
    request += "<b:value i:type=\"c:string\" xmlns:c=\"http://www.w3.org/2001/XMLSchema\">" + EntityLogicalName + "</b:value>";
    request += "</a:KeyValuePairOfstringanyType>";
    if (MetadataId == null)
    { MetadataId = "00000000-0000-0000-0000-000000000000"; }
    request += "<a:KeyValuePairOfstringanyType>";
    request += "<b:key>MetadataId</b:key>";
    request += "<b:value i:type=\"ser:guid\"  xmlns:ser=\"http://schemas.microsoft.com/2003/10/Serialization/\">" + MetadataId + "</b:value>";
    request += "</a:KeyValuePairOfstringanyType>";
    request += "<a:KeyValuePairOfstringanyType>";
    request += "<b:key>RetrieveAsIfPublished</b:key>";
    request += "<b:value i:type=\"c:boolean\" xmlns:c=\"http://www.w3.org/2001/XMLSchema\">" + RetrieveAsIfPublished + "</b:value>";
    request += "</a:KeyValuePairOfstringanyType>";
    request += "<a:KeyValuePairOfstringanyType>";
    request += "<b:key>LogicalName</b:key>";
    request += "<b:value i:type=\"c:string\"   xmlns:c=\"http://www.w3.org/2001/XMLSchema\">" + LogicalName + "</b:value>";
    request += "</a:KeyValuePairOfstringanyType>";
    request += "</a:Parameters>";
    request += "<a:RequestId i:nil=\"true\" /><a:RequestName>RetrieveAttribute</a:RequestName></request>";
    request += "</Execute>";
    request = _getSOAPWrapper(request);

    var req = new XMLHttpRequest();
    req.open("POST", ODataPath, false);
    req.setRequestHeader("Accept", "application/xml, text/xml, */*");
    req.setRequestHeader("Content-Type", "text/xml; charset=utf-8");
    req.setRequestHeader("SOAPAction", "http://schemas.microsoft.com/xrm/2011/Contracts/Services/IOrganizationService/Execute");
    req.send(request);

    if (req.responseXML != null) {
        var attributeData = req.responseXML.selectSingleNode("//b:value");
        if (attributeData != null) {
            var attributeType = attributeData.selectSingleNode("c:AttributeType").text;

            switch (attributeType) {
                case "Picklist":
                    return getPickListTextValue(attributeData, attributeValue);
                    break;
                default:
                    break;
            }


function getPickListTextValue(attributeData, attributeValue) {
    var options = attributeData.selectSingleNode("c:OptionSet//c:Options");
    for (var i = 0; i < options.childNodes.length; i++) {
        var value = options.childNodes[i].selectSingleNode("c:Value").text;
        if (value == attributeValue['Value']) {
            var text = options.childNodes[i].selectSingleNode("c:Label").selectSingleNode("a:UserLocalizedLabel").selectSingleNode("a:Label").text;
            return text;
        }
    }
}

Thus by using the above code, you will be able to retrieve all the items (text & value) of the option set  in JScript.

Hope this post will be helpful to someone, as I struggled with this functionality !!

Good Luck :)