DataTableExtensions.AsEnumerable(DataTable) Method
Definition
Important
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Returns an IEnumerable<T> object, where the generic parameter T is DataRow. This object can be used in a LINQ expression or method query.
public:
[System::Runtime::CompilerServices::Extension]
static System::Data::EnumerableRowCollection<System::Data::DataRow ^> ^ AsEnumerable(System::Data::DataTable ^ source);public static System.Data.EnumerableRowCollection<System.Data.DataRow> AsEnumerable (this System.Data.DataTable source);static member AsEnumerable : System.Data.DataTable -> System.Data.EnumerableRowCollection<System.Data.DataRow><Extension()>
Public Function AsEnumerable (source As DataTable) As EnumerableRowCollection(Of DataRow)Parameters
Returns
An IEnumerable<T> object, where the generic parameter T is DataRow.
Exceptions
The source DataTable is null.
Examples
In the following sample, the DisplayProducts method receives a DataTable that contains a DataColumn named ProductName, extracts the ProductName values and then prints the values.
using System;
using System.Data;
class Program {
public void DisplayProducts(DataTable table) {
var productNames = from products in table.AsEnumerable() select products.Field<string>("ProductName");
Console.WriteLine("Product Names: ");
foreach (string productName in productNames) {
Console.WriteLine(productName);
}
}
static void Main(string[] args) {
DataTable table = new DataTable();
table.Columns.Add("ID");
table.Columns.Add("ProductName");
table.Rows.Add("1", "Chai");
table.Rows.Add("2", "Queso Cabrales");
table.Rows.Add("3", "Tofu");
Program inst = new Program();
inst.DisplayProducts(table);
}
}
Imports System.Console
Module Module1
Public Sub DisplayProducts(ByVal table As DataTable)
Dim productNames = From products In table.AsEnumerable() Select products("ProductName")
WriteLine("Product Names: ")
For Each productName In productNames
WriteLine(productName)
Next
End Sub
Sub Main()
Dim table As DataTable = New DataTable()
table.Columns.Add("ID")
table.Columns.Add("ProductName")
table.Rows.Add("1", "Chai")
table.Rows.Add("2", "Queso Cabrales")
table.Rows.Add("3", "Tofu")
DisplayProducts(table)
End Sub
End Module
Remarks
Language-Integrated Query (LINQ) queries work on data sources that implement the IEnumerable<T> interface or the IQueryable interface. The DataTable class does not implement either interface, so you must call the AsEnumerable method to use the DataTable as a source in the From clause of a LINQ query. You can also obtain custom, domain-specific operators, such as CopyToDataTable, by returning an IEnumerable<T> object.
The enumerable object returned by the AsEnumerable method is permanently bound to the DataTable that produced it. Multiple calls to the AsEnumerable method will return multiple, independent queryable objects that are all bound to the source DataTable.
