Using Transient Fields in an Entity Binding
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## Using Transient Fields in an Entity Binding

The entity bindings from the prior example have been changed in this example to use the entity object both as a value object and an entity object.

Before, the `entryToObject()` method combined the deserialized value object with the key fields to create a new entity object. Now, this method uses the deserialized object directly as an entity, and initializes its key using the fields read from the key tuple.

Before, the `objectToData()` method constructed a new value object using information in the entity. Now it simply returns the entity. Nothing needs to be changed in the entity, since the transient key fields won't be serialized.

    import com.sleepycat.bind.serial.ClassCatalog;
    ...
    public class SampleViews
    {
        ...
        private static class PartBinding extends TupleSerialBinding
        {
            private PartBinding(ClassCatalog classCatalog, Class dataClass)
            {
                super(classCatalog, dataClass);
            }

            public Object entryToObject(TupleInput keyInput, Object dataInput)
            {
                String number = keyInput.readString();
                Part part = (Part) dataInput;
                part.setKey(number);
                return part;
            }

            public void objectToKey(Object object, TupleOutput output)
            {
                Part part = (Part) object;
                output.writeString(part.getNumber());
            }

            public Object objectToData(Object object)
            {
                return object;
            }
        }

        private static class SupplierBinding extends TupleSerialBinding
        {
            private SupplierBinding(ClassCatalog classCatalog, Class dataClass)
            {
                super(classCatalog, dataClass);
            }

            public Object entryToObject(TupleInput keyInput, Object dataInput)
            {
                String number = keyInput.readString();
                Supplier supplier = (Supplier) dataInput;
                supplier.setKey(number);
                return supplier;
            }

            public void objectToKey(Object object, TupleOutput output)
            {
                Supplier supplier = (Supplier) object;
                output.writeString(supplier.getNumber());
            }

            public Object objectToData(Object object)
            {
                return object;
            }
        }

        private static class ShipmentBinding extends TupleSerialBinding
        {
            private ShipmentBinding(ClassCatalog classCatalog, Class dataClass)
            {
                super(classCatalog, dataClass);
            }

            public Object entryToObject(TupleInput keyInput, Object dataInput)
            {
                String partNumber = keyInput.readString();
                String supplierNumber = keyInput.readString();
                Shipment shipment = (Shipment) dataInput;
                shipment.setKey(partNumber, supplierNumber);
                return shipment;
            }

            public void objectToKey(Object object, TupleOutput output)
            {
                Shipment shipment = (Shipment) object;
                output.writeString(shipment.getPartNumber());
                output.writeString(shipment.getSupplierNumber());
            }

            public Object objectToData(Object object)
            {
                return object;
            }
        }
    }

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