PersistentCriteriaEvaluationBehavior Enum

Lists values that specify how filter criteria are evaluated within a transaction.

Assembly : DevExpress.Xpo.v25.2.dll

Declaration

C#
VB.NET

csharp

public enum PersistentCriteriaEvaluationBehavior

Public Enum PersistentCriteriaEvaluationBehavior

Members

Name	Description
`BeforeTransaction`

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.

| | InTransaction |

All objects (Data Store and Cache) are processed by the filter criteria.

Remarks

Values listed by this enumeration specify which objects are processed when a criteria is being evaluated.

Example

Creating a new XPCollection with the criteriaEvaluationBehavior parameter set to BeforeTransaction doesn’t add objects that have been created or changed within a transaction.

csharp

// Creates a new persistent object and saves it to a data store.
MyObject obj1 = new MyObject(session1);
obj1.Name = "Mike";
obj1.Save();
// Creates a new XPCollection.
XPCollection<MyObject> xpCollection = new XPCollection<MyObject>(unitOfWork1);
// Gets the number of objects within the collection.
// count = 1
int count = xpCollection.Count;
// Begins a transaction.
using (UnitOfWork uw = session1.BeginNestedUnitOfWork()) {
    // Creates a new object within the transaction.
    MyObject obj = new MyObject(uw);
    obj.Name = "John";
    // Creates a new collection and populates it.
    XPCollection<MyObject> collection =
    new XPCollection<MyObject>(PersistentCriteriaEvaluationBehavior.BeforeTransaction, uw, null);
    // Gets the number of objects within the collection.
    // count2 = 1
    int count2 = collection.Count;
    uw.CommitChanges();
    // count2 = 1
    count2 = collection.Count;
}

To allow these objects to be added to the collection, the criteriaEvaluationBehavior parameter must be set to InTransaction. Note, this significantly slows down the application’s performance.

csharp

MyObject obj1 = new MyObject(session1);
obj1.Name = "Mike";
obj1.Save();
XPCollection<MyObject> xpCollection = new XPCollection<MyObject>(unitOfWork1);
// Gets the number of objects within the collection.
// count = 1
int count = xpCollection.Count;
using (UnitOfWork uw = session1.BeginNestedUnitOfWork()) {
    MyObject obj = new MyObject(uw);
    obj.Name = "John";
    XPCollection<MyObject> collection =
       new XPCollection<MyObject>(PersistentCriteriaEvaluationBehavior.InTransaction, uw, null);
    // Gets the number of objects within the collection.
    // count2 = 2
    int count2 = collection.Count;
    uw.CommitChanges();
    // count2 = 2
    count2 = collection.Count;
}