How to convert IEnumerable type to List type?

Question

I am trying to fetch certain database values and store them in a datatable. After that I am applying linq to group by all the data with account number.

I am getting the following error

Cannot implicitly convert type

Answer 1

Try this:

class ListItem
{
    public string accountNumber { get; set; }
     
    public List<string> itemNumbers { get; set; }
}

accounts = (from result in dataTable.AsEnumerable() group result by result.Field<string>("accountNumber") into g select new ListItems { accountNumber = g.Key, itemNumbers = g.Select(x => x.Field<string>("<itemNumber>")).ToList() }).ToList();

An explanation is in order:

1. I changed your ListItems class to ListItem and the itemNumbers property to be of type List<string>
2. I am grouping all items (, I don't know the name of the column in your database) to a single ListItem instance, grouped by the accountNumber column, and storing all items in the itemNumbers property