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IObjectSpace.FindObject<ObjectType>(CriteriaOperator, Boolean) Method

Searches for the first object that matches the specified criteria. The object's type is designated by the specified generic type parameter.

Namespace: DevExpress.ExpressApp

Assembly: DevExpress.ExpressApp.v19.2.dll

Declaration

ObjectType FindObject<ObjectType>(
    CriteriaOperator criteria,
    bool inTransaction
)
Function FindObject(Of ObjectType)(
    criteria As CriteriaOperator,
    inTransaction As Boolean
) As ObjectType
ObjectType FindObject<ObjectType>(
    CriteriaOperator criteria,
    bool inTransaction
)
Function FindObject(Of ObjectType)(
    criteria As CriteriaOperator,
    inTransaction As Boolean
) As ObjectType
ObjectType FindObject<ObjectType>(
    CriteriaOperator criteria,
    bool inTransaction
)
Function FindObject(Of ObjectType)(
    criteria As CriteriaOperator,
    inTransaction As Boolean
) As ObjectType

Parameters

Name Type Description
criteria CriteriaOperator

A CriteriaOperator descendant which is the criteria for matching persistent objects.

inTransaction Boolean

true, if the filter takes unsaved changes into account; otherwise, false. Has effect in XPO only.

Parameters

Name Type Description
criteria CriteriaOperator

A CriteriaOperator descendant which is the criteria for matching persistent objects.

inTransaction Boolean

true, if the filter takes unsaved changes into account; otherwise, false. Has effect in XPO only.

Parameters

Name Type Description
criteria CriteriaOperator

A CriteriaOperator descendant which is the criteria for matching persistent objects.

inTransaction Boolean

true, if the filter takes unsaved changes into account; otherwise, false. Has effect in XPO only.

Returns

Type Description
ObjectType

An object which is the first persistent object which matches the specified criteria.

Returns

Type Description
ObjectType

An object which is the first persistent object which matches the specified criteria.

Returns

Type Description
ObjectType

An object which is the first persistent object which matches the specified criteria.

Type Parameters

Name Description
ObjectType

Type Parameters

Name Description
ObjectType

Type Parameters

Name Description
ObjectType

Remarks

The following example uses a Parametrized Action to search for a Person by LastName, and then assigns all deferred tasks to that person.

using System.Collections;
using DevExpress.Data.Filtering;
using DevExpress.ExpressApp;
using DevExpress.ExpressApp.Actions;
using DevExpress.Persistent.Base;
using DevExpress.Persistent.Base.General;
using DevExpress.Persistent.BaseImpl;
// ...
public class AssignTasksController : ObjectViewController<ListView, MainDemo.Module.BusinessObjects.DemoTask> {
    public AssignTasksController() {
        ParametrizedAction assignTasksAction = new ParametrizedAction(
            this, "AssignTasks", PredefinedCategory.Edit, typeof(string));
        assignTasksAction.Execute += AssignTasksAction_Execute;
    }
    private void AssignTasksAction_Execute(object sender, ParametrizedActionExecuteEventArgs e) {
        IObjectSpace objectSpace = View.ObjectSpace;
        string personParamValue = e.ParameterCurrentValue as string;
        CriteriaOperator personCriteria = CriteriaOperator.Parse("Contains([LastName], ?)", personParamValue);
        Person person = objectSpace.FindObject<Person>(personCriteria, true);
        if(person != null) {
            CriteriaOperator taskCriteria = CriteriaOperator.Parse("[Status] = ?", TaskStatus.Deferred);
            IList tasks = objectSpace.GetObjects(
                typeof(MainDemo.Module.BusinessObjects.DemoTask), taskCriteria);
            foreach(MainDemo.Module.BusinessObjects.DemoTask task in tasks) {
                task.AssignedTo = person;
            }
        }
    }
}

When implementing the IObjectSpace interface in the BaseObjectSpace class's descendant, you don't have to implement the FindObject<ObjectType> method. The BaseObjectSpace class' FintObject<ObjectType>(CriteriaOperator criteria, Boolean inTransaction) method invokes a public virtual FindObject(Type objectType, CriteriaOperator criteria, Boolean inTransaction) method. So, you should only override the public virtual BaseObjectSpace.FindObject method to implement an object search.

See Also