Session.FindObject<ClassType>(CriteriaOperator) Method

Searches for the first object of the type designated by the specified generic type parameter which matches the specified criteria.

Namespace: DevExpress.Xpo

Assembly: DevExpress.Xpo.v23.2.dll

NuGet Packages: DevExpress.Win.PivotGrid, DevExpress.Win.TreeMap, DevExpress.Xpo

NuGet Package: DevExpress.Xpo

Declaration

C#

public ClassType FindObject<ClassType>(
    CriteriaOperator criteria
)

VB.NET

Public Function FindObject(Of ClassType)(
    criteria As CriteriaOperator
) As ClassType

Parameters

Name	Type	Description
criteria	CriteriaOperator	A CriteriaOperator descendant which represents the criteria to match persistent objects.

Type Parameters

Name	Description
ClassType	The type of objects to search for.

Returns

Type	Description
ClassType	An object which represents the first persistent object matching the specified criteria. null (Nothing in Visual Basic) if no persistent object matching the criteria is found.

Remarks

Below is an example of using the FindObject<ClassType> method. Here, session is the Session instance.

C#

Person personToUpdate = session.FindObject<Person>(CriteriaOperator.Parse("Name='Michael Suyama'"));
if(personToUpdate != null) {
    personToUpdate.Birthday = new DateTime(1986, 10, 31);
    session.Save(personToUpdate);
}

VB.NET

Dim personToUpdate As Person = session.FindObject(Of Person)(CriteriaOperator.Parse("Name='Michael Suyama'"))
If personToUpdate IsNot Nothing Then
    personToUpdate.Birthday = New Date(1986, 10, 31)
    session.Save(personToUpdate)
End If

Criteria are evaluated on the data store side. Objects created within a transaction (Cache), are not processed by the criteria. Objects modified within a transaction are not processed. Instead, their images, stored in the data store, are processed by the criteria.

To specify how filter criteria are evaluated within a transaction, use the overloaded FindObject method that takes the PersistentCriteriaEvaluationBehavior value as a parameter.

Persistent objects that are marked as deleted in the database (see Deferred and Immediate Object Deletion) are not included in the search.

Related GitHub Examples

The following code snippets (auto-collected from DevExpress Examples) contain references to the FindObject<ClassType>(CriteriaOperator) method.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

C#

XPO_how-to-read-and-manipulate-xpo-objects-stored-in-multiple-databases-simultaneously-t475838/CS/ConsoleApplication/Program.cs#L23

using (UnitOfWork session1 = new UnitOfWork(DB1dal)) {
    Contact contact = session1.FindObject<Contact>(CriteriaOperator.Parse("LastName = ?", "Smith"));
    //connect DB2

winforms-treelist-expression-editor-xpview/CS/E1887/Program.cs#L26

using (UnitOfWork uow = new UnitOfWork()) {
    if (uow.FindObject<Order>(null) != null) return;
    Order parent = new Order(uow);

XPO_how-to-make-user-friendly-object-identifiers-e825/CS/XpoSequencer.cs#L33

using(Session generatorSession = new Session(dataLayer)) {
    XpoSequencer generator = generatorSession.FindObject<XpoSequencer>(new OperandProperty("SequencePrefix") == sequencePrefix);
    if(generator == null) {

XPO_how-to-reopen-a-broken-connection-when-using-a-postgresql-database-e3086/CS/Program.cs#L25

using (UnitOfWork uow = new UnitOfWork()) {
    Person result = uow.FindObject<Person>(null);
    if (result == null) {

XPO_linq-to-xpo-e642/CS/E642/Form1.cs#L28

    // for the first time after the application is started
    Customer cust = XpoDefault.Session.FindObject<Customer>(null);
}

VB.NET

XPO_how-to-read-and-manipulate-xpo-objects-stored-in-multiple-databases-simultaneously-t475838/VB/ConsoleApplication/Program.vb#L23

Using session1 As New UnitOfWork(DB1dal)
    Dim contact As Contact = session1.FindObject(Of Contact)(CriteriaOperator.Parse("LastName = ?", "Smith"))
    'connect DB2

winforms-treelist-expression-editor-xpview/VB/E1887/Program.vb#L27

Using uow As UnitOfWork = New UnitOfWork()
    If uow.FindObject(Of Order)(Nothing) IsNot Nothing Then Return
    Dim parent As Order = New Order(uow)

xpo-how-to-implement-self-referenced-persistent-objects-and-display-them-within-the-xtra-tree-list/VB/CS/Form1.vb#L21

Using uow As UnitOfWork = New UnitOfWork()
    If uow.FindObject(Of Employee)(Nothing) IsNot Nothing Then Return
    Dim AndrewFuller As Employee = New Employee(uow)

XPO_how-to-make-user-friendly-object-identifiers-e825/VB/XpoSequencer.vb#L39

Using generatorSession As New Session(dataLayer)
    Dim generator As XpoSequencer = generatorSession.FindObject(Of XpoSequencer)(New OperandProperty("SequencePrefix") = sequencePrefix)
    If generator Is Nothing Then

XPO_how-to-reopen-a-broken-connection-when-using-a-postgresql-database-e3086/VB/Program.vb#L22

Using uow As New UnitOfWork()
    Dim result As Person = uow.FindObject(Of Person)(Nothing)
    If result Is Nothing Then