ModelItem Class

ModelItem Class

.NET Framework (current version)
 

Represents a single item in the editing model. An item can be anything from a complex data structure down to a color or integer.

Namespace:   System.Activities.Presentation.Model
Assembly:  System.Activities.Presentation (in System.Activities.Presentation.dll)


public abstract class ModelItem : INotifyPropertyChanged

NameDescription
System_CAPS_protmethodModelItem()

Creates a new instance of the ModelItem class.

NameDescription
System_CAPS_pubpropertyAttributes

Gets the attributes declared on this item.

System_CAPS_pubpropertyContent

Gets the ContentPropertyAttribute of the item, or null.

System_CAPS_pubpropertyItemType

Gets the type of object that the item represents.

System_CAPS_pubpropertyName

Gets or sets the name or ID of the item.

System_CAPS_pubpropertyParent

Gets the item that is the parent of this item.

System_CAPS_pubpropertyParents

Gets all parents of this item.

System_CAPS_pubpropertyProperties

Gets the public properties on this item.

System_CAPS_pubpropertyRoot

Gets the item that is the root of this tree.

System_CAPS_pubpropertySource

Gets the property that provided this value.

System_CAPS_pubpropertySources

Gets all the properties that hold this value.

System_CAPS_pubpropertyView

Gets a DependencyObject that graphically represents this item.

NameDescription
System_CAPS_pubmethodBeginEdit()

Opens an editing scope for the designer. After an editing scope is open, all changes across all objects will be saved into the scope until the transaction is completed or reverted. Editing scopes can be nested, but must be committed in order.

System_CAPS_pubmethodBeginEdit(Boolean)

Opens an editing scope for the designer.

System_CAPS_pubmethodBeginEdit(String)

Opens an editing scope for the designer. After an editing scope is open, all changes across all objects will be saved into the scope until the transaction is completed or reverted. Editing scopes can be nested, but must be committed in order.

System_CAPS_pubmethodBeginEdit(String, Boolean)

Opens an editing scope for the designer.

System_CAPS_pubmethodEquals(Object)

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_protmethodFinalize()

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethodGetCurrentValue()

Returns the current value of the underlying model object that the ModelItem is wrapping.

System_CAPS_pubmethodGetHashCode()

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_protmethodMemberwiseClone()

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_pubmethodToString()

Returns a string representation of the underlying model object contained in this model item.(Overrides Object.ToString().)

NameDescription
System_CAPS_pubeventPropertyChanged

Implements INotifyPropertyChanged. Use this event to listen for changes to the model. This is also used by the data binding features of WPF.

NameDescription
System_CAPS_pubmethodFocus()

Overloaded. Sets the keyboard focus on the specified designer item.(Defined by ModelItemExtensions.)

System_CAPS_pubmethodFocus(Int32)

Overloaded. Sets the keyboard focus on the specified designer item.(Defined by ModelItemExtensions.)

System_CAPS_pubmethodGetEditingContext()

Retrieves the editing context of the specified model item.(Defined by ModelItemExtensions.)

System_CAPS_pubmethodGetModelPath()

Retrieves the path of the specified model item.(Defined by ModelItemExtensions.)

System_CAPS_pubmethodIsParentOf(ModelItem)

Returns a value that indicates whether the first specified designer item is a parent of the second specified designer item.(Defined by ModelItemExtensions.)

You can access the item’s properties through its Properties collection and make changes to the values of the properties.

A ModelItem is a wrapper around the underlying data model of the designer. You can access the underlying model through the GetCurrentValue method.

System_CAPS_noteNote

Any changes you make to an object returned from the GetCurrentValue method will not be reflected by the serialization and undo systems of the designer.

The ModelItem can be thought of as a thin proxy for an object at which it points. First define a simple Animal object.


public class Animal
{
    // simple property
    public string Name { get; set; }
    // complex property 
    public Location Residence { get; set; } 
    // list 
    public List<Animal> CloseRelatives { get; set; }
    // dictionary
    public Dictionary<string, object> Features { get; set; } 
}

public class Location
{
    public string StreetAddress { get; set; }
    public string City { get; set; }
    public string State { get; set; } 
}

Secondly, create an instance of that Animal and a ModelItem that is a proxy for it. The object can then be retrieved by calling GetCurrentValue. The following code also shows how to use other properties defined by ModelItem.


EditingContext ec = new EditingContext();
var companion1 = new Animal { Name = "Houdini the parakeet" };
var companion2 = new Animal { Name = "Groucho the fish" };
var animal = new Animal 
   {
      Name = "Sasha the pug",
      Residence = new Location 
      {
         StreetAddress = "123 Main Street",
         City = "AnyTown",
         State = "Washington"
      },
      Features = new Dictionary<string, object> { 
         {"noise", "snort" },
         {"MeanTimeUntilNaps", TimeSpan.FromMinutes(15) }
      },
      CloseRelatives = new List<Animal> { companion1, companion2 } 
   };
ModelTreeManager mtm = new ModelTreeManager(ec);  mtm.Load(animal);
ModelItem mi = mtm.Root;

//Testing other properties of the class
ModelItem root = mtm.Root;
Assert.IsTrue(root.GetCurrentValue() == animal, "GetCurrentValue() returns same object");
Assert.IsTrue(root.ItemType == typeof(Animal),"ItemType describes the item");
Assert.IsTrue(root.Parent == null,"root parent is null");
Assert.IsTrue(root.Source == null, "root source is null");
Assert.IsTrue(((List<Animal>)root.Properties["CloseRelatives"].ComputedValue)[0] == companion1, 
   "ComputedValue of prop == actual object");
Assert.IsFalse(((List<Animal>)root.Properties["CloseRelatives"].ComputedValue)[0] == companion2, 
   "ComputedValue of prop == actual object");
Assert.AreEqual(root.Properties["Residence"].
   Value.
   Properties["StreetAddress"].
   Value.GetCurrentValue(), "123 Main Street", "get actual value back out");
Assert.AreEqual(root, root.Properties["Residence"].Parent, "property points to owner");
ModelItem location = root.Properties["Residence"].Value;
Assert.AreEqual(root.Properties["Residence"], location.Source, "sources point to the right place");


.NET Framework
Available since 4.0

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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