IsInstanceOfTypeFunction Class

A custom function that determines whether a particular object is of a specified type or derives from it.

Namespace: DevExpress.Xpo.Metadata

Assembly: DevExpress.Xpo.v19.2.dll

Declaration

public class IsInstanceOfTypeFunction :
    ICustomFunctionOperatorBrowsable,
    ICustomFunctionOperator
Public Class IsInstanceOfTypeFunction
    Implements ICustomFunctionOperatorBrowsable,
               ICustomFunctionOperator
public class IsInstanceOfTypeFunction :
    ICustomFunctionOperatorBrowsable,
    ICustomFunctionOperator
Public Class IsInstanceOfTypeFunction
    Implements ICustomFunctionOperatorBrowsable,
               ICustomFunctionOperator

Remarks

This function is automatically registered in XPO applications. So, you can use it right from the start.

The IsInstanceOfTypeFunction custom function operator takes 2 operands:

  1. The first operand specifies the object whose type will be checked.
  2. The second operand specifies the fully qualified name of the required type.

Assume you have a collection of Employee objects. Employees can either be objects of the LocalEmployee, LocalTemporaryEmployee, or ForeignEmployee types:


public class LocalEmployee : Employee { /* ... */ }

public class LocalTemporaryEmployee : LocalEmployee { /* ... */ }

public class ForeignEmployee : Employee { /* ... */ }

The following code snippet demonstrates how the employees collection can be filtered to contain only local employees, including the temporary ones.


using DevExpress.Xpo;
using DevExpress.Data.Filtering;
//...
XPCollection<EmployeeBase> employees = new XPCollection<EmployeeBase>(Session);
employees.Criteria = CriteriaOperator.Parse("IsInstanceOfType(This, ?)", typeof(LocalEmployee).FullName);

The IsInstanceOfTypeFunction function is automatically registered in XPO applications.

Inheritance

Object
IsInstanceOfTypeFunction
See Also