IObjectSpace.FindObject<ObjectType>(CriteriaOperator) Method
Searches for the first object that matches the specified criteria. The object’s type is designated by the specified generic type parameter. The search takes uncommitted changes into account.
Namespace: DevExpress.ExpressApp
Assembly: DevExpress.ExpressApp.v23.2.dll
NuGet Package: DevExpress.ExpressApp
Declaration
Parameters
| Name | Type | Description |
|---|---|---|
| criteria | CriteriaOperator | A CriteriaOperator descendant which is the criteria for matching persistent objects. |
Type Parameters
| Name | Description |
|---|---|
| ObjectType | The Type of objects that are retrieved. |
Returns
| Type | Description |
|---|---|
| ObjectType | An object which is the first persistent object which matches the specified criteria. |
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);
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) method invokes a public virtual FindObject(Type objectType, CriteriaOperator criteria, Boolean inTransaction) method passing true as the inTransaction parameter. So, to implement an object search, override the public virtual BaseObjectSpace.FindObject method.
Related GitHub Examples
The following code snippets (auto-collected from DevExpress Examples) contain references to the FindObject<ObjectType>(CriteriaOperator) method.
Note
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