What is the proper syntax for this:
Dim qry As <??> = From f In dirInfo.GetFiles("*.QBW") Select File = f.FullName, Include = True
Dim dt As DataTable = qry.CopyToDataTable()
I tried as "IEnumerable(Of DataRow)" but that didn't work. At runtime it said:
Unable to cast object of type 'WhereSelectArrayIterator
2[System.IO.FileInfo,VB$AnonymousType_02[System.String,System.Boolean]]' to type 'System.Collections.Generic.IEnumerable`1[System.Data.DataRow]'.
I try to apply Linq in most situations so I am more familiar with it but this doesn't seem like the right problem to use it on. So going back to the old and true way... Per Everyone's help, I am arriving that the best way to do this would be:
Dim dt As New DataTable()
dt.Columns.Add("File", GetType(String))
dt.Columns.Add("Include", GetType(Boolean))
For Each f as FileInfo In dirInfo.GetFiles("*.QBW")
dt.Rows.Add(f.FullName, True)
Next
Here is a small solution written in c#
Use select(x => new {})... and type it as IEnumerable
private static void Main(string[] args)
{
var dirInfo = new DirectoryInfo(@"c:\windows\temp\");
IEnumerable<dynamic> qry = dirInfo.GetFiles("*.txt").Select(x => new { x.FullName, x.Extension });
foreach (var item in qry)
{
Console.WriteLine(string.Concat(item.Extension, " -> ", item.FullName));
}
Console.ReadKey();
}
Edit, here's a vb version
Private Shared Sub Main(args As String())
Dim dirInfo = New DirectoryInfo("c:\windows\temp\")
Dim qry As IEnumerable(Of dynamic) = dirInfo.GetFiles("*.txt").[Select](Function(x) New From { _
x.FullName, _
x.Extension _
})
For Each item As var In qry
Console.WriteLine(String.Concat(item.Extension, " -> ", item.FullName))
Next
Console.ReadKey()
End Sub
Update 2
Now as clearly stated in the question the typing is unclear, this can be solved by using IEnumerable. However this is not an optimal solution, instead I recommend to build an object and store your data there. But for minor applications I suppose it'll do.
var keyword) evades the actual question asked. Third, it seems to me (but I'm not 100% certain) that you've changed the meaning of the code with your usage of new { … }.
Dim qry = dirInfo.GetFiles("*.QBW").[Select](Function(f) New With { _
f.FullName, _
.Include = True _
})
Or simply turn Option Infer On, and don't use anything, like
Dim qry = From f In dirInfo.GetFiles("*.QBW") Select File = f.FullName, Include = True
Take a look here for a more in depth discussion.
However, to use CopyToDataTable() the type needs to a DataRow derived type.
What do you intend to use the DataTable for, there are lots of places in .net where a DataTable is not required?
The solution is in the error message you pasted... you want an IEnumerable(Of FileInfo).
Of FileInfo, there is an anonymous type involved.
Select is creating new instances of an anoymous type.DataRow is not involved in the query, it would never be Of DataRow. For this particular problem, if you want a DataTable, you would create it manually. Create the table structure, then loop over the query result and add new rows.
System.IO.DirectoryInfo, given the usage.