Property Injection¶

Example

IoC.Configuration allows property injection in XML configuration file (for property injection in modules see Type Bindings in IoC.Configuration Modules).
The property value is injected using injectedProperties element under element service/implementation or selfBoundService.
Normally we should rely on constructor injection. However property injection can be used to handle circular references, when two types reference each other.
Property injection is done after the object is constructed. Therefore, the values of properties set by property injection will override the values set by constructor.

Example ¶

In the example below interface SharedServices.Interfaces.IInterface2 is bound to type SharedServices.Implementations.Interface2_Impl3.

When type SharedServices.Interfaces.IInterface2 is injected into another type via a constructor or property injection, an instance of SharedServices.Implementations.Interface2_Impl3 will be created and its properties will be set the following way:
- Property Property1 will be set to a System.Double value de-serialized from textual value 148.3.
- Property Property2 will be injected by IoC.Configuration, since element injectedObject is used for this property.
- Property Wheel1 will be set to an instance of SharedServices.Interfaces.IWheel de-serialized from a textual value 27,45.
  
  Note
  
  A parameter serializer for type SharedServices.Interfaces.IWheel should exist for type SharedServices.Interfaces.IWheel under element iocConfiguration/parameterSerializers/serializers. See Parameter Serializers for more details on how constructor and property values are de-serialized.

Note

IoC.Configuration will automatically register a self bound service for a type specified in element injectedObject, if the type is not an abstract type or an interface, and if it is not already registered in configuration file. Therefore, no need to register a binding for type SharedServices.Implementations.Interface3_Impl3 used in injectedObject for property Property2, since this type is a non-abstract and non-interface.

Note

Using injectedObject, we can specify a type other than a type registered for type of property Property2 somewhere else. By using element injectedObject we explicitly state the type of the object that should be injected, no matter what types are registered for the type of the property.

Note

The implementation type SharedServices.Implementations.Interface2_Impl3 should have a setter for property Property2, which should be assignable from type SharedServices.Implementations.Interface3_Impl3. However, the setter property is not required in interface SharedServices.Interfaces.IInterface2 specified in service element.

<service type="SharedServices.Interfaces.IInterface2" assembly="shared_services">
    <implementation type="SharedServices.Implementations.Interface2_Impl3"
                                        assembly="shared_services"
                                        scope="singleton">
        <injectedProperties>
            <double name="Property1" value="148.3" />

            <injectedObject name="Property2"
                            type="SharedServices.Implementations.Interface3_Impl3"
                            assembly="shared_services" />
            <object name="Wheel1"
                    type="SharedServices.Interfaces.IWheel"
                    assembly="shared_services" value="27,45" />
        </injectedProperties>
    </implementation>
<service>

Property Injection¶

Example¶

Example ¶