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

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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".

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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?

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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
}