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Generic GetObject(PersistentTypeSelector,IQuery) Method
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Chili.Opf3 Namespace > ObjectContext Class > GetObject Method : Generic GetObject(PersistentTypeSelector,IQuery) Method




typeSelector
Delegate invoked before each creating of a persistent object. This allows to dynamically change the type of the created persistent object or ignore some objects.
query
An instance of a class that implements the IQuery interface. This query is compiled and used to retrieve the object from the storage.
Fetches the first object matching the conditions and returns it.

Syntax

Visual Basic (Declaration) 
Overloads Public Overridable Function GetObject(Of T)( _
   ByVal typeSelector As PersistentTypeSelector, _
   ByVal query As IQuery _
) As T
Visual Basic (Usage)Copy Code
Dim instance As ObjectContext
Dim typeSelector As PersistentTypeSelector
Dim query As IQuery
Dim value As T
 
value = instance.GetObject(Of T)(typeSelector, query)
C# 
public virtual T GetObject<T>( 
   PersistentTypeSelector typeSelector,
   IQuery query
)
Managed Extensions for C++ 
public: virtual T GetObject<T>( 
   PersistentTypeSelector* typeSelector,
   IQuery* query
)
C++/CLI 
public:
virtual T GetObjectgeneric<typename T>
( 
   PersistentTypeSelector^ typeSelector,
   IQuery^ query
)

Parameters

typeSelector
Delegate invoked before each creating of a persistent object. This allows to dynamically change the type of the created persistent object or ignore some objects.
query
An instance of a class that implements the IQuery interface. This query is compiled and used to retrieve the object from the storage.

Type Parameters

T

Return Value

The first object matching the IQuery.

Example

The following example introduces to the use of the GetObject routine.
C#Copy Code
// Creates a new ObjectContext that uses an MsSql Server as storage. 
ObjectContext context = new ObjectContext(new MsSqlStorage("sa", "",  
    "localhost", "application")); 
  
// ... Other code. 
  
// Get the first user matching the name and sorts them by name. 
User user = context.GetObject<User>(new PersistentTypeSelector(MySelection), 
    new ObjectQuery<User>("Name like {0} SortBy Name Asc", "%mith%")); 
  
// If the user object is null nothing that matches has been found. 
if (user == null) 
    Debug.WriteLine("No object found!"); 
else 
    Debug.WriteLine( 
        string.Format("Object with name {0} has been found.",  
        user.Name)); 
 
// ... 
 
private void MySelection(object sender, FetchingStorageRecordEventArgs e) 
{ 
    if (e.DataRecord["Type"] == "1") 
    { 
        // Switch the type of the persistent that is created to User1. 
        e.Type = typeof(User1); 
    } 
    // Have a persistent of type User created. 
    e.Type = typeof(User); 
} 
    

Remarks

Executes a query on the storage and returns the first object that matches the query. If no object is found Null is returned.

Requirements

Platforms: Windows 2000, Windows XP family, Windows Server 2003 family, Windows Vista family

See Also