How to: Project an Object Graph
This topic illustrates how to project, or populate, an object graph from XML.
Example
The following code populates an object graph with the Address, PurchaseOrder, and PurchaseOrderItem classes from the Sample XML File: Typical Purchase Order (LINQ to XML) XML document.
class Address
{
public enum AddressUse
{
Shipping,
Billing,
}
private AddressUse addressType;
private string name;
private string street;
private string city;
private string state;
private string zip;
private string country;
public AddressUse AddressType {
get { return addressType; } set { addressType = value; }
}
public string Name {
get { return name; } set { name = value; }
}
public string Street {
get { return street; } set { street = value; }
}
public string City {
get { return city; } set { city = value; }
}
public string State {
get { return state; } set { state = value; }
}
public string Zip {
get { return zip; } set { zip = value; }
}
public string Country {
get { return country; } set { country = value; }
}
public override string ToString()
{
StringBuilder sb = new StringBuilder();
sb.Append(String.Format("Type: {0}\n",
addressType == AddressUse.Shipping ? "Shipping" : "Billing"));
sb.Append(String.Format("Name: {0}\n", name));
sb.Append(String.Format("Street: {0}\n", street));
sb.Append(String.Format("City: {0}\n", city));
sb.Append(String.Format("State: {0}\n", state));
sb.Append(String.Format("Zip: {0}\n", zip));
sb.Append(String.Format("Country: {0}\n", country));
return sb.ToString();
}
}
class PurchaseOrderItem
{
private string partNumber;
private string productName;
private int quantity;
private Decimal usPrice;
private string comment;
private DateTime shipDate;
public string PartNumber {
get { return partNumber; } set { partNumber = value; }
}
public string ProductName {
get { return productName; } set { productName = value; }
}
public int Quantity {
get { return quantity; } set { quantity = value; }
}
public Decimal USPrice {
get { return usPrice; } set { usPrice = value; }
}
public string Comment {
get { return comment; } set { comment = value; }
}
public DateTime ShipDate {
get { return shipDate; } set { shipDate = value; }
}
public override string ToString()
{
StringBuilder sb = new StringBuilder();
sb.Append(String.Format("PartNumber: {0}\n", partNumber));
sb.Append(String.Format("ProductName: {0}\n", productName));
sb.Append(String.Format("Quantity: {0}\n", quantity));
sb.Append(String.Format("USPrice: {0}\n", usPrice));
if (comment != null)
sb.Append(String.Format("Comment: {0}\n", comment));
if (shipDate != DateTime.MinValue)
sb.Append(String.Format("ShipDate: {0:d}\n", shipDate));
return sb.ToString();
}
}
class PurchaseOrder
{
private string purchaseOrderNumber;
private DateTime orderDate;
private string comment;
private List<Address> addresses;
private List<PurchaseOrderItem> items;
public string PurchaseOrderNumber {
get { return purchaseOrderNumber; } set { purchaseOrderNumber = value; }
}
public DateTime OrderDate {
get { return orderDate; } set { orderDate = value; }
}
public string Comment {
get { return comment; } set { comment = value; }
}
public List<Address> Addresses {
get { return addresses; } set { addresses = value; }
}
public List<PurchaseOrderItem> Items {
get { return items; } set { items = value; }
}
public override string ToString()
{
StringBuilder sb = new StringBuilder();
sb.Append(String.Format("PurchaseOrderNumber: {0}\n", purchaseOrderNumber));
sb.Append(String.Format("OrderDate: {0:d}\n", orderDate));
sb.Append("\n");
sb.Append("Addresses\n");
sb.Append("=====\n");
foreach (Address address in addresses)
{
sb.Append(address);
sb.Append("\n");
}
sb.Append("Items\n");
sb.Append("=====\n");
foreach (PurchaseOrderItem item in items)
{
sb.Append(item);
sb.Append("\n");
}
return sb.ToString();
}
}
class Program {
public static void Main()
{
XElement po = XElement.Load("PurchaseOrder.xml");
PurchaseOrder purchaseOrder = new PurchaseOrder {
PurchaseOrderNumber = (string)po.Attribute("PurchaseOrderNumber"),
OrderDate = (DateTime)po.Attribute("OrderDate"),
Addresses = (
from a in po.Elements("Address")
select new Address {
AddressType = ((string)a.Attribute("Type") == "Shipping") ?
Address.AddressUse.Shipping :
Address.AddressUse.Billing,
Name = (string)a.Element("Name"),
Street = (string)a.Element("Street"),
City = (string)a.Element("City"),
State = (string)a.Element("State"),
Zip = (string)a.Element("Zip"),
Country = (string)a.Element("Country")
}
).ToList(),
Items = (
from i in po.Element("Items").Elements("Item")
select new PurchaseOrderItem {
PartNumber = (string)i.Attribute("PartNumber"),
ProductName = (string)i.Element("ProductName"),
Quantity = (int)i.Element("Quantity"),
USPrice = (Decimal)i.Element("USPrice"),
Comment = (string)i.Element("Comment"),
ShipDate = (i.Element("ShipDate") != null) ?
(DateTime)i.Element("ShipDate") :
DateTime.MinValue
}
).ToList()
};
Console.WriteLine(purchaseOrder);
}
}
Class Address
Public Enum AddressUse
Shipping
Billing
End Enum
Private addressTypeVal As AddressUse
Private nameVal As String
Private streetVal As String
Private cityVal As String
Private stateVal As String
Private zipVal As String
Private countryVal As String
Public Property AddressType() As AddressUse
Get
Return addressTypeVal
End Get
Set(ByVal value As AddressUse)
addressTypeVal = value
End Set
End Property
Public Property Name() As String
Get
Return nameVal
End Get
Set(ByVal value As String)
nameVal = value
End Set
End Property
Public Property Street() As String
Get
Return streetVal
End Get
Set(ByVal value As String)
streetVal = value
End Set
End Property
Public Property City() As String
Get
Return cityVal
End Get
Set(ByVal value As String)
cityVal = value
End Set
End Property
Public Property State() As String
Get
Return stateVal
End Get
Set(ByVal value As String)
stateVal = value
End Set
End Property
Public Property Zip() As String
Get
Return zipVal
End Get
Set(ByVal value As String)
zipVal = value
End Set
End Property
Public Property Country() As String
Get
Return countryVal
End Get
Set(ByVal value As String)
countryVal = value
End Set
End Property
Public Overrides Function ToString() As String
Dim sb As StringBuilder = New StringBuilder()
sb.Append(String.Format("Type: {0}" + vbNewLine, _
IIf(AddressType = AddressUse.Shipping, "Shipping", "Billing")))
sb.Append(String.Format("Name: {0}" + vbNewLine, Name))
sb.Append(String.Format("Street: {0}" + vbNewLine, Street))
sb.Append(String.Format("City: {0}" + vbNewLine, City))
sb.Append(String.Format("State: {0}" + vbNewLine, State))
sb.Append(String.Format("Zip: {0}" + vbNewLine, Zip))
sb.Append(String.Format("Country: {0}" + vbNewLine, Country))
Return sb.ToString()
End Function
End Class
Class PurchaseOrderItem
Private partNumberVal As String
Private productNameVal As String
Private quantityVal As Integer
Private usPriceVal As Decimal
Private commentVal As String
Private shipDateVal As DateTime
Public Property PartNumber() As String
Get
Return partNumberVal
End Get
Set(ByVal value As String)
partNumberVal = value
End Set
End Property
Public Property ProductName() As String
Get
Return productNameVal
End Get
Set(ByVal value As String)
productNameVal = value
End Set
End Property
Public Property Quantity() As Integer
Get
Return quantityVal
End Get
Set(ByVal value As Integer)
quantityVal = value
End Set
End Property
Public Property USPrice() As Decimal
Get
Return usPriceVal
End Get
Set(ByVal value As Decimal)
usPriceVal = value
End Set
End Property
Public Property Comment() As String
Get
Return commentVal
End Get
Set(ByVal value As String)
commentVal = value
End Set
End Property
Public Property ShipDate() As DateTime
Get
Return shipDateVal
End Get
Set(ByVal value As DateTime)
shipDateVal = value
End Set
End Property
Public Overrides Function ToString() As String
Dim sb As StringBuilder = New StringBuilder()
sb.Append(String.Format("PartNumber: {0}" + vbNewLine, PartNumber))
sb.Append(String.Format("ProductName: {0}" + vbNewLine, ProductName))
sb.Append(String.Format("Quantity: {0}" + vbNewLine, Quantity))
sb.Append(String.Format("USPrice: {0}" + vbNewLine, USPrice))
If (Comment <> Nothing) Then
sb.Append(String.Format("Comment: {0}" + vbNewLine, Comment))
End If
If (ShipDate <> DateTime.MinValue) Then
sb.Append(String.Format("ShipDate: {0:d}" + vbNewLine, ShipDate))
End If
Return sb.ToString()
End Function
End Class
Class PurchaseOrder
Private purchaseOrderNumberVal As String
Private orderDateVal As DateTime
Private commentVal As String
Private addressesVal As List(Of Address)
Private itemsVal As List(Of PurchaseOrderItem)
Public Property PurchaseOrderNumber() As String
Get
Return purchaseOrderNumberVal
End Get
Set(ByVal value As String)
purchaseOrderNumberVal = value
End Set
End Property
Public Property OrderDate() As DateTime
Get
Return orderDateVal
End Get
Set(ByVal value As DateTime)
orderDateVal = value
End Set
End Property
Public Property Comment() As String
Get
Return commentVal
End Get
Set(ByVal value As String)
commentVal = value
End Set
End Property
Public Property Addresses() As List(Of Address)
Get
Return addressesVal
End Get
Set(ByVal value As List(Of Address))
addressesVal = value
End Set
End Property
Public Property Items() As List(Of PurchaseOrderItem)
Get
Return itemsVal
End Get
Set(ByVal value As List(Of PurchaseOrderItem))
itemsVal = value
End Set
End Property
Public Overrides Function ToString() As String
Dim sb As StringBuilder = New StringBuilder()
sb.Append(String.Format("PurchaseOrderNumber: {0}" _
+ vbNewLine, PurchaseOrderNumber))
sb.Append(String.Format("OrderDate: {0:d}" + vbNewLine, OrderDate))
sb.Append(vbNewLine)
sb.Append("Addresses" + vbNewLine)
sb.Append("=====" + vbNewLine)
For Each address As Address In Addresses
sb.Append(address)
sb.Append(vbNewLine)
Next
sb.Append("Items" + vbNewLine)
sb.Append("=====" + vbNewLine)
For Each item As PurchaseOrderItem In Items
sb.Append(item)
sb.Append(vbNewLine)
Next
Return sb.ToString()
End Function
End Class
Sub Main()
Dim po As XElement = XElement.Load("PurchaseOrder.xml")
Dim purchOrder = New PurchaseOrder With { _
.PurchaseOrderNumber = po.@<PurchaseOrderNumber>, _
.OrderDate = Convert.ToDateTime(po.@<OrderDate>), _
.Addresses = ( _
From a In po.<Address> _
Select New Address With { _
.AddressType = IIf(a.@<Type> = "Shipping", _
Address.AddressUse.Shipping, _
Address.AddressUse.Billing), _
.Name = a.<Name>.Value, _
.Street = a.<Street>.Value, _
.City = a.<City>.Value, _
.State = a.<State>.Value, _
.Zip = a.<Zip>.Value, _
.Country = a.<Country>.Value _
} _
).ToList(), _
.Items = ( _
From i In po.<Items>.<Item> _
Select New PurchaseOrderItem With { _
.PartNumber = i.@<PartNumber>, _
.ProductName = i.<ProductName>.Value, _
.Quantity = i.<Quantity>.Value, _
.USPrice = i.<USPrice>.Value, _
.Comment = i.<Comment>.Value, _
.ShipDate = IIf(i.<ShipDate>.Value <> Nothing, _
Convert.ToDateTime(i.<ShipDate>.Value), _
DateTime.MinValue) _
} _
).ToList() _
}
Console.WriteLine(purchOrder)
End Sub
In this example, the result of the LINQ query is returned as an IEnumerable<T> of PurchaseOrderItem. The items in the PurchaseOrder class are of type IEnumerable<T> of PurchaseOrderItem. The code uses the ToList<TSource> extension method to create a List<T> collection from the results of the query.
The example produces the following output:
PurchaseOrderNumber: 99503
OrderDate: 10/20/1999
Addresses
=====
Type: Shipping
Name: Ellen Adams
Street: 123 Maple Street
City: Mill Valley
State: CA
Zip: 10999
Country: USA
Type: Billing
Name: Tai Yee
Street: 8 Oak Avenue
City: Old Town
State: PA
Zip: 95819
Country: USA
Items
=====
PartNumber: 872-AA
ProductName: Lawnmower
Quantity: 1
USPrice: 148.95
Comment: Confirm this is electric
PartNumber: 926-AA
ProductName: Baby Monitor
Quantity: 2
USPrice: 39.98
ShipDate: 5/21/1999