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How to sort elements on multiple keys (LINQ to XML)

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This article shows how to sort on multiple keys in C# and Visual Basic.

Example: Sort XML elements on multiple keys

This example sorts on two keys: shipping postal code (primary) and order date. It uses XML document Sample XML file: Customers and orders.

XElement co = XElement.Load("CustomersOrders.xml");
var sortedElements =
    from c in co.Element("Orders").Elements("Order")
    orderby (string)c.Element("ShipInfo").Element("ShipPostalCode"),
            (DateTime)c.Element("OrderDate")
    select new {
        CustomerID = (string)c.Element("CustomerID"),
        EmployeeID = (string)c.Element("EmployeeID"),
        ShipPostalCode = (string)c.Element("ShipInfo").Element("ShipPostalCode"),
        OrderDate = (DateTime)c.Element("OrderDate")
    };
foreach (var r in sortedElements)
    Console.WriteLine("CustomerID:{0} EmployeeID:{1} ShipPostalCode:{2} OrderDate:{3:d}",
        r.CustomerID, r.EmployeeID, r.ShipPostalCode, r.OrderDate);

Dim co As XElement = XElement.Load("CustomersOrders.xml")
Dim result = _
    From c In co.<Orders>.<Order> _
    Order By c.<ShipInfo>.<ShipPostalCode>.Value, Convert.ToDateTime(c.<OrderDate>.Value) _
    Select New With { _
        .CustomerID = c.<CustomerID>.Value, _
        .EmployeeID = c.<EmployeeID>.Value, _
        .ShipPostalCode = c.<ShipInfo>.<ShipPostalCode>.Value, _
        .OrderDate = Convert.ToDateTime(c.<OrderDate>.Value) _
    }
For Each r In result
    Console.WriteLine("CustomerID:{0} EmployeeID:{1} ShipPostalCode:{2} OrderDate:{3:d}", _
                r.CustomerID, r.EmployeeID, r.ShipPostalCode, r.OrderDate)
Next

This example produces the following output:

CustomerID:LETSS EmployeeID:1 ShipPostalCode:94117 OrderDate:6/25/1997
CustomerID:LETSS EmployeeID:8 ShipPostalCode:94117 OrderDate:10/27/1997
CustomerID:LETSS EmployeeID:6 ShipPostalCode:94117 OrderDate:11/10/1997
CustomerID:LETSS EmployeeID:4 ShipPostalCode:94117 OrderDate:2/12/1998
CustomerID:GREAL EmployeeID:6 ShipPostalCode:97403 OrderDate:5/6/1997
CustomerID:GREAL EmployeeID:8 ShipPostalCode:97403 OrderDate:7/4/1997
CustomerID:GREAL EmployeeID:1 ShipPostalCode:97403 OrderDate:7/31/1997
CustomerID:GREAL EmployeeID:4 ShipPostalCode:97403 OrderDate:7/31/1997
CustomerID:GREAL EmployeeID:6 ShipPostalCode:97403 OrderDate:9/4/1997
CustomerID:GREAL EmployeeID:3 ShipPostalCode:97403 OrderDate:9/25/1997
CustomerID:GREAL EmployeeID:4 ShipPostalCode:97403 OrderDate:1/6/1998
CustomerID:GREAL EmployeeID:3 ShipPostalCode:97403 OrderDate:3/9/1998
CustomerID:GREAL EmployeeID:3 ShipPostalCode:97403 OrderDate:4/7/1998
CustomerID:GREAL EmployeeID:4 ShipPostalCode:97403 OrderDate:4/22/1998
CustomerID:GREAL EmployeeID:4 ShipPostalCode:97403 OrderDate:4/30/1998
CustomerID:HUNGC EmployeeID:3 ShipPostalCode:97827 OrderDate:12/6/1996
CustomerID:HUNGC EmployeeID:1 ShipPostalCode:97827 OrderDate:12/25/1996
CustomerID:HUNGC EmployeeID:3 ShipPostalCode:97827 OrderDate:1/15/1997
CustomerID:HUNGC EmployeeID:4 ShipPostalCode:97827 OrderDate:7/16/1997
CustomerID:HUNGC EmployeeID:8 ShipPostalCode:97827 OrderDate:9/8/1997
CustomerID:LAZYK EmployeeID:1 ShipPostalCode:99362 OrderDate:3/21/1997
CustomerID:LAZYK EmployeeID:8 ShipPostalCode:99362 OrderDate:5/22/1997

Example: Sort XML that's in a namespace

This example does the same sort as the first, but for XML that's in a namespace. It uses XML document Sample XML file: Customers and orders in a namespace.

For more information, see Namespaces overview.

XElement co = XElement.Load("CustomersOrdersInNamespace.xml");
XNamespace aw = "http://www.adventure-works.com";
var sortedElements =
    from c in co.Element(aw + "Orders").Elements(aw + "Order")
    orderby (string)c.Element(aw + "ShipInfo").Element(aw + "ShipPostalCode"),
            (DateTime)c.Element(aw + "OrderDate")
    select new
    {
        CustomerID = (string)c.Element(aw + "CustomerID"),
        EmployeeID = (string)c.Element(aw + "EmployeeID"),
        ShipPostalCode = (string)c.Element(aw + "ShipInfo").Element(aw + "ShipPostalCode"),
        OrderDate = (DateTime)c.Element(aw + "OrderDate")
    };
foreach (var r in sortedElements)
    Console.WriteLine("CustomerID:{0} EmployeeID:{1} ShipPostalCode:{2} OrderDate:{3:d}",
        r.CustomerID, r.EmployeeID, r.ShipPostalCode, r.OrderDate);

Imports <xmlns='http://www.adventure-works.com'>

Module Module1
    Sub Main()
        Dim co As XElement = XElement.Load("CustomersOrdersInNamespace.xml")
        Dim result = _
            From c In co.<Orders>.<Order> _
            Order By c.<ShipInfo>.<ShipPostalCode>.Value, Convert.ToDateTime(c.<OrderDate>.Value) _
            Select New With { _
                .CustomerID = c.<CustomerID>.Value, _
                .EmployeeID = c.<EmployeeID>.Value, _
                .ShipPostalCode = c.<ShipInfo>.<ShipPostalCode>.Value, _
                .OrderDate = Convert.ToDateTime(c.<OrderDate>.Value) _
            }
        For Each r In result
            Console.WriteLine("CustomerID:{0} EmployeeID:{1} ShipPostalCode:{2} OrderDate:{3:d}", _
                        r.CustomerID, r.EmployeeID, r.ShipPostalCode, r.OrderDate)
        Next
    End Sub
End Module

This example produces the following output:

CustomerID:LETSS EmployeeID:1 ShipPostalCode:94117 OrderDate:6/25/1997
CustomerID:LETSS EmployeeID:8 ShipPostalCode:94117 OrderDate:10/27/1997
CustomerID:LETSS EmployeeID:6 ShipPostalCode:94117 OrderDate:11/10/1997
CustomerID:LETSS EmployeeID:4 ShipPostalCode:94117 OrderDate:2/12/1998
CustomerID:GREAL EmployeeID:6 ShipPostalCode:97403 OrderDate:5/6/1997
CustomerID:GREAL EmployeeID:8 ShipPostalCode:97403 OrderDate:7/4/1997
CustomerID:GREAL EmployeeID:1 ShipPostalCode:97403 OrderDate:7/31/1997
CustomerID:GREAL EmployeeID:4 ShipPostalCode:97403 OrderDate:7/31/1997
CustomerID:GREAL EmployeeID:6 ShipPostalCode:97403 OrderDate:9/4/1997
CustomerID:GREAL EmployeeID:3 ShipPostalCode:97403 OrderDate:9/25/1997
CustomerID:GREAL EmployeeID:4 ShipPostalCode:97403 OrderDate:1/6/1998
CustomerID:GREAL EmployeeID:3 ShipPostalCode:97403 OrderDate:3/9/1998
CustomerID:GREAL EmployeeID:3 ShipPostalCode:97403 OrderDate:4/7/1998
CustomerID:GREAL EmployeeID:4 ShipPostalCode:97403 OrderDate:4/22/1998
CustomerID:GREAL EmployeeID:4 ShipPostalCode:97403 OrderDate:4/30/1998
CustomerID:HUNGC EmployeeID:3 ShipPostalCode:97827 OrderDate:12/6/1996
CustomerID:HUNGC EmployeeID:1 ShipPostalCode:97827 OrderDate:12/25/1996
CustomerID:HUNGC EmployeeID:3 ShipPostalCode:97827 OrderDate:1/15/1997
CustomerID:HUNGC EmployeeID:4 ShipPostalCode:97827 OrderDate:7/16/1997
CustomerID:HUNGC EmployeeID:8 ShipPostalCode:97827 OrderDate:9/8/1997
CustomerID:LAZYK EmployeeID:1 ShipPostalCode:99362 OrderDate:3/21/1997
CustomerID:LAZYK EmployeeID:8 ShipPostalCode:99362 OrderDate:5/22/1997

See also