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<title>Berkeley DB Reference Guide: Serializable Entity - Using transient fields in an entity binding</title>
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<td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Java API Tutorial - Serializable Entity</dl></h3></td>
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<p>
<h3 align=center>Serializable Entity - Using transient fields in an entity binding</h3>
<p>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.</p>
<p>Before, the <b>dataToObject</b> 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.</p>
<p>Before, the <b>objectToValue</b> 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.</p>
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<blockquote><pre>
public class SampleViews
{
    ...
    private static class PartBinding extends TupleSerialBinding
    {
        private PartBinding(TupleFormat keyFormat,
                            SerialFormat valueFormat)
        {
            super(keyFormat, valueFormat);
        }
<p>
        public Object dataToObject(TupleInput keyInput, Object valueInput)
            throws IOException
        {
            String number = keyInput.readString();
<b>            Part part = (Part) valueInput;
            part.setKey(number);
            return part;
</b>        }
<p>
        public void objectToKey(Object object, TupleOutput output)
            throws IOException
        {
            Part part = (Part) object;
            output.writeString(part.getNumber());
        }
<p>
        public Object objectToValue(Object object)
            throws IOException
        {
<b>            return object;
</b>        }
    }
<p>
    private static class SupplierBinding extends TupleSerialBinding
    {
        private SupplierBinding(TupleFormat keyFormat,
                                SerialFormat valueFormat)
        {
            super(keyFormat, valueFormat);
        }
<p>
        public Object dataToObject(TupleInput keyInput, Object valueInput)
            throws IOException
        {
            String number = keyInput.readString();
<b>            Supplier supplier = (Supplier) valueInput;
            supplier.setKey(number);
            return supplier;
</b>        }
<p>
        public void objectToKey(Object object, TupleOutput output)
            throws IOException
        {
            Supplier supplier = (Supplier) object;
            output.writeString(supplier.getNumber());
        }
<p>
        public Object objectToValue(Object object)
            throws IOException
        {
<b>            return object;
</b>        }
    }
<p>
    private static class ShipmentBinding extends TupleSerialBinding
    {
        private ShipmentBinding(TupleFormat keyFormat,
                                SerialFormat valueFormat)
        {
            super(keyFormat, valueFormat);
        }
<p>
        public Object dataToObject(TupleInput keyInput, Object valueInput)
            throws IOException
        {
            String partNumber = keyInput.readString();
            String supplierNumber = keyInput.readString();
<b>            Shipment shipment = (Shipment) valueInput;
            shipment.setKey(partNumber, supplierNumber);
            return shipment;
</b>        }
<p>
        public void objectToKey(Object object, TupleOutput output)
            throws IOException
        {
            Shipment shipment = (Shipment) object;
            output.writeString(shipment.getPartNumber());
            output.writeString(shipment.getSupplierNumber());
        }
<p>
        public Object objectToValue(Object object)
            throws IOException
        {
<b>            return object;
</b>        }
    }
}
</pre></blockquote>
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