Using PdxInstanceFactory to Create a PdxInstances

This topic discusses using the PdxInstanceFactory to create a PdxInstances in VMware Tanzu GemFire. You can use the PdxInstanceFactory interface to create a PdxInstance from raw data when the domain class is not available on the server.

This can be particularly useful when you need an instance of a domain class for plug in code such as a function or a loader. If you have the raw data for the domain object (the class name and each field’s type and data), then you can explicitly create a PdxInstance. The PdxInstanceFactory is very similar to the PdxWriter except that after writing each field, you need to call the create method which returns the created PdxInstance.

To create a factory call RegionService.createPdxInstanceFactory. A factory can only create a single instance. To create multiple instances create multiple factories or use PdxInstance.createWriter() to create subsequent instances. Using PdxInstance.createWriter() is usually faster.

When you create a PdxInstance, set as least one identity field using the markIndentityField method. If you do not mark an identity field, the PdxInstanceequals and hashCode methods will use all PDX fields to compare objects and consequently, will not perform as well. It is important that the fields used by your equals and hashCode implementations are the same fields that you mark as identity fields.

The following is a code example of using PdxInstanceFactory:

PdxInstance pi = cache.createPdxInstanceFactory("com.company.DomainObject")
   .writeInt("id", 37)
   .markIdentityField("id")
   .writeString("name", "Mike Smith")
   .writeObject("favoriteDay", cache.createPdxEnum("com.company.Day", "FRIDAY", 5))
   .create();

For more information, see PdxInstanceFactory in the Java API documentation.

Enum Objects as PdxInstances

You can now work with enum objects as PdxInstances. When you fetch an enum object from the cache, you can now deserialize it as a PdxInstance. To check whether a PdxInstance is an enum, use the PdxInstance.isEnum method. An enum PdxInstance will have one field named “name” whose value is a String that corresponds to the enum constant name.

An enum PdxInstance is not writable; if you call createWriter it will throw an exception.

The RegionService has a method that allows you to create a PdxInstance that represents an enum. See RegionService.createPdxEnum in the Java API documentation.