Casting into grouping row

I dont know why i am 开发者_StackOverflowgetting the following exception how can I cast into grouping Row ? What does grouping row means

Quick answer: change the code to

foreach(var InvoiceHeader in InvoiceHeadercollection)

The linq code has generated a new class, which you can think of like this:

class AutoGeneratedClass :  IEnumerable<DataRow>
{
    public string Key { get; }  // The InvoiceAccount field
}

(It's not called "AutoGeneratedClass"; I'm just using that so it follows the syntax we know). Because there's no name for this automatically generated class, you have to use "var".

Look at your LINQ query, you are using group by - InvoiceHeaderCollection is not a collection of data rows, it's an IGrouping<DataRow>, a different group for each different "Invoice account". - what did you want to do with the grouping? Or did you intend to order your rows by Invoice account?

InvoiceHeaderCollection is a collection of groups, the groups is something like:

      Key               Value
 invoice account1      datarow1 //the value is a `DataRow`
                       datarow2
                       datarow4
 invoice account2      datarow3
 invoice account3      datarow5 

So I think you need:

foreach(var g in InvoiceHeaderCollection)
{
    DataRow[] rows = g.ToArray();   //to get all the DataRows in the group
    //maybe another loop through the rows
}