docs/geode-native-docs-cpp/serialization/cpp-serialization/using-pdxserializer.html.md.erb

---
title:  Serialize Your Domain Objects with PdxSerializer and PdxWrapper
---

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For domain objects that you cannot or do not want to modify, use the `PdxSerializer` and the `PdxWrapper` classes to serialize and deserialize the object's fields.

You register a `PdxSerializer` implementation for the entire cache, programming it for all of the domain objects that you handle in this way. This way you do not have to implement the `PdxSerializable` interface for each domain class.

The `PdxSerializer` allows domain classes to be serialized and deserialized as PDXs without modification of the domain class. It requires only that the domain class have a constructor accessible to the `PdxSerializer` to create an instance. The domain class will be held in a wrapper class, `PdxWrapper`.

`PdxSerializer` has the following methods:

-   The `toData` method returns true if the PdxSerializer was able to serialize the user object, false if not.
-   If the PdxSerializer was able to deserialize the object, the `fromData` method returns a void pointer to the user object to be wrapped in a `PdxWrapper`.

When you later reference the user object, use the `PdxWrapper` class. `PdxWrapper` holds a shared reference to the object in the local cache and is used during serialization and deserialization. `PdxWrapper` acts as a container for the user domain object and needs to wrap every instance of the object that uses a registered `PdxSerializer`. The object instance will not be modified. In addition, when using `PdxWrapper`, you will need to provide a function pointer to a "deallocator", which will delete the user object when the reference is no longer held.

The following code example defines a user object and a `PdxSerializer`. It then registers the new `PdxSerializer` and then uses `PdxWrapper` to put the object in a region and retrieve the object from a region.

``` pre
class UserClass
{
public:

  int m_int;
  string m_string;

  UserClass(int intVal, string stringVal)
  {
    m_int = intVal;
    m_string = stringVal;
  }

  static void deallocate(void * object, char * className)
  {
    if (strcmp(className, "com.example.UserClass") == 0) {
      UserClass * userObject = reinterpret_cast<UserClass*>(object);
      delete userObject;
    }
  }
};

class UserPdxSerializer : public PdxSerializer
{
public:

  void* fromData(char * className, PdxReaderPtr pdxReader)
  {
    if (strcmp(className, "com.example.UserClass") != 0) {
      return NULL;
    }

    int intVal = pdxReader->readInt("m_int");
    string stringVal = pdxReader->readString("m_string");

    UserClass * userObject = new UserClass(intVal, stringVal);

    return (void*) userObject;
  }

  bool toData(void * object, char * className, PdxWriterPtr pdxWriter)
  {
    if (strcmp(className, "com.example.UserClass") != 0) {
      return false;
    }

    UserClass * userObject = reinterpret_cast<UserClass*>(object);

    pdxWriter->writeInt("m_int", userObject->m_int);
    pdxWriter->writeString("m_string", userObject->m_string);

    return true;
  }

  UserDeallocator getDeallocator(char * className)
  {
    if (strcmp(className, "com.example.UserClass") == 0) {
      return UserClass::deallocate;
    } else {
      return NULL;
    }
  }
};

// Register a user PDX serializer

Serializable::registerPdxSerializer(new UserPdxSerializer);

// Put a user object into a region.

UserClass * userObject = new UserClass(123, "someValue");
PdxWrapperPtr pdxWrapper = new PdxWrapper(userObject, "com.example.UserClass", 
                                          UserClass::deallocate);
region->put("key", pdxWrapper);

// Get a user object from a region.

pdxWrapper = dynCast<PdxWrapperPtr>(region->get("key"));
UserClass * userObject = reinterpret_cast<UserClass*>(pdxWrapper->getObject());
```