Adding a dataset lookup on purchase requisition form in EP

Today, I will be discussing about one of the issue which  any one has encountered while adding a lookup on data set and it is not visible in EP specially on Purchase Requisition details form. So I will be sharing here the code snippet which can used to show that data set lookup for any field.

void dataSetLookup(SysDataSetLookup _sysDataSetLookup)
{
     Query      query;
     TableId    lookupTableNum;

     lookuptablenum = tableNum(PurchReqTable);

    _sysDataSetLookup.parmLookupFields(new List(Types::String));
    _sysDataSetLookup.parmLookupFields().addEnd(fieldStr(PurchReqTable,PurchReqId));
    _sysDataSetLookup.parmLookupFields().addEnd(fieldStr(PurchReqTable,TestField1));
    _sysDataSetLookup.parmLookupFields().addEnd(fieldStr(PurchReqTable,PurchReqId));
    _sysDataSetLookup.parmLookupFields().addEnd(fieldStr(PurchReqTable,Originator));
    _sysDataSetLookup.parmSelectField(fieldStr(PurchReqTable,TestField1));

    query = new Query(queryStr (PurchReqTableListPage));
    query.dataSourceNo(1).addRange(fieldNum(PurchReqTable,TestField1type)).value(enum2str(RequisitionType::Type1));
    query.dataSourceNo(1).addRange(fieldNum(PurchReqTable,RequisitionStatus)).value(enum2str(PurchReqRequisitionStatus::Approved));
    query.dataSourceNo(1).addRange(fieldNum(PurchReqTable,BlanketOnHold)).value(enum2str(NoYes::no));

    query.allowCrossCompany(true);

    _sysDataSetLookup.parmQuery(query);
    _sysDataSetLookup.parmDataSet(SysDataSetBuilder::constructLookupDataSet(lookupTableNum).toDataSet());
}

Note : This construct method is quite helpful in showing lookup