Linq to DataSet Left Join

[mickey_pt]

Hello

Once again with a linq query problem...
The query works but only retrieve the joined rows, i want to retrieve all rows in the first datatable.

My current query:

Dim q = From regE In (From registoE In _dtRegistosAEnviar.AsEnumerable
               Group registoE By colaborador = registoE.Field(Of String)("Colaborador") Into grupoE = Group
               Select New With {
                   .Colaborador = colaborador,
                   .Seg = grupoE.Sum(Function(registoE) registoE.Field(Of Decimal)("Seg"))
               }).AsEnumerable,
               regS In (From registoS In _dtRegistosEnviados.AsEnumerable
               Group registoS By colaborador = registoS.Field(Of String)("Colaborador") Into grupoS = Group
               Select New With {
                   .Colaborador = colaborador,
                   .Seg = grupoS.Sum(Function(registoS) registoS.Field(Of Decimal)("Seg"))
               }).AsEnumerable
               Where (regE.Colaborador = regS.Colaborador)

[jmcilhinney]

This was the first result when I Googled:

http://www.codeguru.com/columns/vb/article.php/c15057

[mickey_pt]

Thanks JMC

But that doesn't work, i already tested two different ways, the first one, that was similar to that one in Codeguru, the INTO clause after the Equals isn't recognized, i used this in here. Then i looked to another page at MSDN doesn't know which one and change the query to the one that i wrote...

[jmcilhinney]

Hmmm... I didn't, and don't right now, have the time to experiment and I've never done it before myself. I'll try later in the day if you still need it then.

[mickey_pt]

Thanks but the join problem it's kind of solved.
Now i have other problem, and i don't know what to do. In the selected rows of the join, if i put only the fields of the left table, the query works fine, but if i put the row that i need from the right table, when the table don't have values for the matching it raises a nullexception.

I already tried to check if the value is nothing, but without luck.

Here's the code:

Dim query = From regE In (From registoE In _dtRegistosAEnviar.AsEnumerable
           Group registoE By colaborador = registoE.Field(Of String)("Colaborador") Into grupoE = Group
           Select New With {
               .Colaborador = colaborador,
               .Seg = grupoE.Sum(Function(registoE) registoE.Field(Of Decimal)("Seg"))
           }).AsEnumerable
           Group Join regS In (From registoS In _dtRegistosEnviados.AsEnumerable
           Group registoS By colaborador = registoS.Field(Of String)("Colaborador") Into grupoS = Group
           Select New With {
               .ColaboradorS = colaborador,
               .SegS = grupoS.Sum(Function(registoS) registoS.Field(Of Decimal?)("Seg"))
           }).AsEnumerable
           On regE.Colaborador Equals regS.ColaboradorS Into juncao = Group
            From ele In juncao.DefaultIfEmpty
            Select New With {
               .Colaborador = regE.Colaborador,
               .HorasPorLancar = regE.Seg,
               .TheErrorColum= ele.SegS <<<<<<<<<  ERROR >>>>>>>
            }

If i remove the line that throws the exception it works fine and i have all the values, but when i put this error column it throws the exception.

I already tried this

IIf(ele.SegS Is Nothing, 0, ele.SegS)

and this

If(ele.SegS Is Nothing, 0, ele.SegS)

and this

IIf(IsDBNull(ele.SegS), 0, ele.SegS)

and this

If(IsDBNull(ele.SegS), 0, ele.SegS)