How to get field value from AXgroup in EP

string  var = (string)this.EpDataSourceName.GetDataSet().DataSetViews["DataSourceName"].GetCurrent().GetFieldValue("Fieldname");

Example:
I have get vendor account value from PurchReqCreateDataset
string  vendorID = (string)this.PurchReqCreateDs.GetDataSet.DataSetViews["PurchReqTable"].GetCurrent().GetFieldValue("VendAccount");