filtering data through odata service and get distinct data

function getDistinctLocations(selectedProducts, selectedCharNums) {
    var productFilterString = "";
    selectedProducts.forEach(function(product, index) {
        if (index > 0) {
            productFilterString += " or ";
        }
        productFilterString += "PRODUCT eq '" + product + "'";
    });

    var charNumFilterString = "";
    selectedCharNums.forEach(function(charNum, index) {
        if (index > 0) {
            charNumFilterString += " or ";
        }
        charNumFilterString += "CHARNUM eq '" + charNum + "'";
    });

    var oModel = new sap.ui.model.odata.v2.ODataModel("/YourODataService");
    oModel.read("/YourEntitySet", {
        urlParameters: {
            "$apply": "groupby((LOCATION))",
            "$filter": productFilterString + " and (" + charNumFilterString + ")"
        },
        success: function(data) {
            // Process distinct locations data
            // Populate a dropdown or list with distinct locations
        },
        error: function(error) {
            // Handle error
        }
    });
}