4.8. Binding Data Configurations
Configuration (1) defines the creation rules for the com.acme.Order bean instance (the top level bean). See the following configurations for details:
- You should create each of the beans instances ((1), (2), (3) but not (4)) at the very start of the message (on the order element). Do this because there will only ever be a single instance of these beans in the populated model.
- Configurations (1.a) and (1.b) define the wiring configuration for wiring the Header and ListOrderItem bean instances ((2) and (3)) into the order bean instance (see the beanIdRef attribute values and how the reference the beanId values defined on (2) and (3)). The property attributes on (1.a) and (1.b) define the Order bean properties on which the wirings are to be made.Note also that beans can also be wired into an object based on their Java class type (beanType), or by being annotated with a specific Annotation (beanAnnotation).Configuration (2) creates the com.acme.Header bean instance.
- Configuration (2.a) defines a value binding onto the Header.date property. Note that the data attribute defines where the binding value is selected from the source message; in this case it is coming from the header/date element. Also note how it defines a decodeParam sub-element. This configures the DateDecoder.
- Configuration (2.b) defines a value binding configuration onto the Header.customerNumber property. Note how to configure the data attribute to select a binding value from an element attribute on the source message.Configuration (2.b) also defines an expression binding where the order total is calculated and set on the Header.total property. The execOnElement attribute tells Smooks that this expression needs to be evaluated (and bound/rebound) on the order-item element. So, if there are multiple order-item elements in the source message, this expression will be executed for each order-item and the new total value rebound into the Header.total property. Note how the expression adds the current orderItem total to the current order total (Header.total).
- Configuration (2.d) defines an expression binding, where a running total is calculated by adding the total for each order item (quantity * price) to the current total. Configuration (3) creates the ListOrderItem bean instance for holding the OrderItem instances.
- Configuration (3.a) wires all beans of type com.acme.OrderItem ( i.e. (4)) into the list. Note how this wiring does not define a property attribute. This is because it wires into a Collection (same applies if wiring into an array). You can also perform this wiring using the beanIdRef attribute instead of the beanType attribute.
- Configuration (4) creates the OrderItem bean instances. Note how the createOnElement is set to the order-item element. This allows for a new instance of this bean to be created for every order-item element (and wired into the ListOrderItem (3.a)).
If the createOnElement attribute for this configuration was not set to the order-item element (if, for example, it was set to one of the order, header or order-items elements), then only a single OrderItem bean instance would be created and the binding configurations ((4.a) etc) would overwrite the bean instance property bindings for every order-item element in the source message, that is, you would be left with a ListOrderItem with just a single OrderItem instance containing the order-item data from the last order-item encountered in the source message.
